WO2021257441A1 - Mitigation of excessive handovers in a wireless communication system - Google Patents

Mitigation of excessive handovers in a wireless communication system Download PDF

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Publication number
WO2021257441A1
WO2021257441A1 PCT/US2021/037199 US2021037199W WO2021257441A1 WO 2021257441 A1 WO2021257441 A1 WO 2021257441A1 US 2021037199 W US2021037199 W US 2021037199W WO 2021257441 A1 WO2021257441 A1 WO 2021257441A1
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WIPO (PCT)
Prior art keywords
handover
measurement
criterion
signal
cell
Prior art date
Application number
PCT/US2021/037199
Other languages
French (fr)
Inventor
Sharda RANJAN
Naga Chandan Babu Gudivada
Kuo-Chun Lee
Xipeng Zhu
Tom Chin
Jiaheng LIU
Yongle WU
Arvind Vardarajan Santhanam
Viswanath SANKARAN
Yue HONG
Xuqiang ZHANG
Shan QING
Original Assignee
Qualcomm Incorporated
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Publication date
Priority claimed from PCT/CN2020/096113 external-priority patent/WO2021253163A1/en
Application filed by Qualcomm Incorporated filed Critical Qualcomm Incorporated
Publication of WO2021257441A1 publication Critical patent/WO2021257441A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/0005Control or signalling for completing the hand-off
    • H04W36/0055Transmission or use of information for re-establishing the radio link
    • H04W36/0058Transmission of hand-off measurement information, e.g. measurement reports
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/0005Control or signalling for completing the hand-off
    • H04W36/0083Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837Determination of triggering parameters for hand-off
    • H04W36/008375Determination of triggering parameters for hand-off based on historical data

Definitions

  • aspects of the present disclosure generally relate to wireless communication and techniques to mitigate excessive handovers of a user equipment (UE) in a wireless communication system.
  • UE user equipment
  • Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on.
  • a wireless communication system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
  • UE user equipment
  • Different base stations or network access nodes may implement different radio communication protocols including fourth- generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth-generation (5G) systems which may be referred to as New Radio (NR) systems.
  • 4G systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems
  • 5G systems which may be referred to as New Radio (NR) systems.
  • NR which also may be referred to as 5G for brevity, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3 GPP).
  • a UE may be configured to establish a connection to a serving cell of a base station.
  • the base station may provide a measurement configuration to the UE to cause the UE to perform a signal measurement of neighbor cells of that same base station or another base station.
  • the UE may send a measurement report that is triggered when the signal measurements match a reporting criterion for a measurement reporting event.
  • radio signals of a neighboring base station which may be referred to as a target base station, will provide an enhanced connection with a UE relative to a currently serving (or source) base station, the UE may be handed over from the source base station to the target base station.
  • Such techniques may be referred to as handover procedures or mobility procedures, and help to provide continuous connectivity to a UE as it moves in a wireless communications system.
  • handover procedures or mobility procedures
  • Such techniques may be referred to as handover procedures or mobility procedures, and help to provide continuous connectivity to a UE as it moves in a wireless communications system.
  • the UE may experience excessive handovers. Excessive handovers can disrupt connectivity and diminish the user experience.
  • the systems, methods, and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.
  • One innovative aspect of the subject matter described in this disclosure can be implemented in a method performed by an apparatus of a user equipment (UE).
  • the method may include establishing at least a first connection with a serving cell of a base station (BS).
  • the method may include receiving a measurement configuration that includes a reporting criterion for a measurement reporting event.
  • the reporting criterion may be configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell.
  • the triggered measurement report may be associated with initiating a handover of the UE from the serving cell to the neighbor cell.
  • the method may include monitoring for an occurrence of measurement reporting event using a handover restraining criterion.
  • the handover restraining criterion may be based on a UE-configured parameter different from the one or more network-provided parameters.
  • the method may include communicating the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • the UE may include at least one modem configured to establish at least a first connection with a serving cell of a BS, and obtain a measurement configuration that includes a reporting criterion for a measurement reporting event.
  • the reporting criterion may be configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell.
  • the triggered measurement report may be associated with initiating a handover of the UE from the serving cell to the neighbor cell.
  • the UE may include a processing system configured to monitor for an occurrence of measurement reporting event using a handover restraining criterion.
  • the handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters.
  • the at least one modem may be configured to communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • the method may include establishing a connection with a user equipment (UE) via a serving cell of the first base station.
  • the method may include preparing a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold.
  • the method may include transmitting a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • the apparatus may include a processing system configured to establish a connection with a user equipment (UE) via a serving cell of the first base station, and prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold.
  • the apparatus may include at least one modem configured to output a measurement configuration for transmission to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • Figure 1 shows a pictorial diagram conceptually illustrating an example of a wireless communication system.
  • Figure 2 shows a block diagram conceptually illustrating an example of a base station (BS) in communication with a user equipment (UE).
  • Figure 3 shows a block diagram conceptually illustrating an example wireless communication system in which a UE may have dual connectivity.
  • Figure 4 shows a pictorial diagram conceptually illustrating an example of a UE experiencing a ping-pong situation with excessive handovers.
  • Figure 5 shows a signaling diagram illustrating a handover process.
  • Figure 6 shows a flowchart illustrating an example process for triggered measurement reports using a handover restraining criterion.
  • Figure 7 shows a flowchart illustrating an example process with example handover restraining criteria.
  • Figure 8 shows a flowchart illustrating an example process using a combination of handover restraining criteria.
  • Figure 9 shows a diagram illustrating an example of a signal measurement plot over time and corresponding behavior to enable or disable a handover restraining criterion.
  • Figure 10A shows a flow diagram of an example process for monitoring for an occurrence of a measurement reporting event.
  • Figure 10B shows a flow diagram of an example process of a measurement evaluation.
  • Figure 11 shows example measurement reporting events based on combinations of their respective reporting criterion and a handover restraining criterion.
  • Figure 12 shows a flowchart illustrating an example process to mitigate excessive handovers using a network-provided cell blacklist.
  • Figure 13 shows a conceptual diagram of an example configuration message according to some implementations.
  • Figure 14 shows a block diagram of an example wireless communication device.
  • the described implementations may be implemented in any device, system or network that is capable of transmitting and receiving radio frequency signals according to any of the wireless communication standards, including any of the IEEE 802.11 standards, the Bluetooth ® standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband- CDMA (W-CDMA), Evolution Data Optimized (EV-DO), lxEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals that are used to communicate within a wireless, cellular or internet of things (IOT) network, such as a system,
  • a wireless communication system may include one or more radio access networks (RANs) that provide access for a user equipment (UE) to communicate with other nodes in the wireless communication system.
  • RAN radio access network
  • a radio access network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs).
  • BS base stations
  • Different types of base stations may be referred to as aNodeB, an LTE evolved NodeB (eNB), a next generation NodeB (gNB), an access point (AP), a radio head, a transmit receive point (TRP), among other examples, depending on the wireless communication standard that the base station supports.
  • eNB LTE evolved NodeB
  • gNB next generation NodeB
  • AP access point
  • TRP transmit receive point
  • LTE base stations may make up an LTE radio access network (RAN).
  • the LTE RAN (sometimes also referred to as an LTE network) provides access to the wireless communication system.
  • one or more 5G base stations may make up a 5G New Radio (NR) RAN, and may be referred to as a 5G NR network that provides access to the wireless communication system.
  • NR New Radio
  • the LTE network and 5GNR network may be two examples of a radio access network that can be used to communicate to a core network of the wireless communication system.
  • a wireless communication session or association between a user equipment (UE) and a base station (BS) may be referred to as a radio connection (or just a “connection”).
  • a standalone access (SA) mode may refer to a connection in which the initial acquisition and connection are made between the UE and the RAN.
  • a non-standalone access (NS A) mode may refer to the use of multiple connections that include a primary connection to a first base station and a secondary connection to a second base station.
  • the examples in this disclosure refer to NSA connections that use dual connectivity (DC).
  • a UE may be configured to establish a first connection to an eNB of an LTE RAN and a second connection to a gNB of a 5G NR RAN.
  • a radio resource control (RRC) configuration for the first connection and second connection may include information about the serving cells of the eNB and the gNB for the UE to use.
  • RRC radio resource control
  • a base station may send an RRC Connection Reconfiguration message.
  • Reasons to change the RRC configuration may include a handover or change to a neighbor cell (such as another cell of the same base station or another cell of a different base station).
  • the base station may provide a measurement configuration to the UE to aid in the detection and selection of appropriate neighbor cells.
  • the measurement configuration may include different reporting criteria corresponding to different measurement reporting events. An occurrence of a measurement reporting event occurs when a reporting criterion for that measurement reporting event is satisfied. The occurrence of the measurement reporting event may trigger the UE to transmit a measurement report (also referred to as triggered measurement report). Thus, the UE may be configured to send a particular measurement report when a respective reporting criterion is satisfied.
  • Some of the measurement reports and their respective reporting criteria are designed to initiate a handover based on a signal measurement of a neighboring cell in comparison to a measurement of the current serving cell, a measurement threshold, or both.
  • the signal measurement may be based on a signal strength, such as received signal strength indicator (RSSI), a received signal received power (RSRP). Alternatively, the signal measurement may be based on a signal-to-interference-plus noise ratio (SINR) or a reference signal received quality (RSRQ).
  • RSSI received signal strength indicator
  • RSRP received signal received power
  • SINR signal-to-interference-plus noise ratio
  • RSRQ reference signal received quality
  • the reporting criterion may be repetitively satisfied prompting repetitive handovers. For example, after a first handover, the UE may send a subsequent measurement report that initiates another handover back to the previous cell or to another neighbor cell. The cycle may be referred to as a “ping-pong” situation, event or occurrence when repetitive handovers occur between two or more cells.
  • a UE may trigger multiple handover events when the UE is in overlapping coverage areas of multiple neighboring cells.
  • the UE may use a handover restraining criterion (in addition to the reporting criterion or as a modification to the reporting criterion) to suppress the sending of a trigger measurement report that would otherwise cause a handover.
  • the handover restraining criterion may include an expiration of a delay timer, a signal quality comparison, a signal quality precondition, a cell blacklist, a signal strength change threshold, or any combination thereof.
  • the handover restraining criterion may be adjusted based on a frequency of handovers in a preceding time period or at a particular location. In some implementations, the handover restraining criterion may be modified based on movement speed of the UE or a change in location of the UE. In some implementations, a change in location of the UE may be determined based on a variation in the signal strength of a serving cell over a time period. The handover restraining criterion may be used in conjunction with the reporting criteria for some triggered measurement reports to reduce the occurrence of handover when the UE measures a similar signal strength from multiple cells.
  • This disclosure provides several example handover restraining criteria that may be used to mitigate excessive handovers.
  • handover restraining criterion include an expiration of a delay timer that is initiated after a previous handover, a determination that a current signal strength of the serving cell has changed more than a signal strength change threshold, a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period, a determination that the neighbor signal quality is above a signal quality precondition threshold for a time period, and a determination that the neighbor cell is not included in a cell blacklist provided by the base station. While some portions of this disclosure include some example handover restraining criteria that are used in particular combinations, the example handover restraining criteria may be used in different combinations.
  • one example handover restraining criterion may include an expiration of a delay timer that is initiated after a previous handover.
  • the duration of the delay timer may be based on a frequency of handovers.
  • the frequency of handovers may be determined based on a count of handovers over a recent time period.
  • the UE may determine whether the frequency of handovers is in a normal frequency category, a medium frequency category or a high frequency category using different thresholds.
  • the normal frequency category, the medium frequency category and the high frequency category may be related to a quantity of handovers over a time period or may be based on an average quantity of handovers per second.
  • the duration of delay timer when the frequency of handovers is in the high frequency category, the duration of delay timer may be longer than when the frequency of handovers is in the medium frequency category or normal frequency category. Similarly, when the frequency of handovers is in the medium frequency category, the duration of delay timer may be longer than when the frequency of handovers is in the normal frequency category. In some implementations, when the frequency of handovers is in the normal frequency category, the duration of delay timer may be zero or a minimal value (such as approximately 320 milliseconds or a time indicated by a timeToTrigger parameter of the measurement configuration). [0034] In some implementations, the handover restraining criterion may be adjusted or become conditional based on UE movement.
  • the UE may determine UE movement based on a change in a current signal strength of the current serving cell.
  • UE movement refers to a change in geographic location of the UE relative to one or more base stations. If the current signal strength has changed more than a signal strength change threshold, the UE may infer that the UE is moving. Conversely, if the current signal strength has not changed more than a signal strength change threshold, the UE may infer that the UE is stationary (not moving).
  • the UE may disable or reduce the handover restraining criterion such that measurement reports may be triggered based on the reporting criterion. However, when the UE is stationary, the handover restraining criterion may be implemented to prevent a triggered measurement report that may otherwise cause an unnecessary handover.
  • the handover restraining criterion may be based on a signal quality over a time period.
  • the signal quality may provide a further condition before sending a triggered measurement report that would otherwise cause an undesirable handover.
  • the signal quality may refer to a signal-to-noise ratio (SNR) or a similar metric that is based on quality of the signal.
  • SNR signal-to-noise ratio
  • the signal quality may be a different metric than is used with the reporting criteria of the measurement configuration. For example, the reporting criteria may use a measurement based on signal strength, while the signal quality may be based on SNR measurements over a time period.
  • the handover restraining criterion may be based on a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the current serving cell by at least a signal quality comparison threshold over a time period. Alternatively, the handover restraining criterion may be based on a determination that the neighbor signal quality is above a signal quality precondition threshold over a time period.
  • the signal quality comparison threshold or the signal quality precondition threshold may be a configurable value such as 2 decibels (dB) or 3 dB or 5 dB, etc.
  • the UE may check the handover restraining criterion to confirm that the handover restraining criterion based on signal quality is satisfied. If the handover restraining criterion is not satisfied, the UE may refrain from sending the triggered measurement report that would otherwise result in an undesirable handover.
  • 3GPP technical standard 38.331.
  • 3GPP TS 38.331 defines Event A3, Event A4, and Event A5 and different triggered measurement reporting events.
  • Each of these Events A3-A5 may be triggered based on signal strength measurements (such as RSSI or RSRP).
  • Signal strength measurements such as RSSI or RSRP.
  • Event A3 may traditionally be triggered when a neighbor cell signal strength becomes stronger, such as by an offset amount stronger, than the current serving cell.
  • Event A4 may traditionally be triggered when a neighbor cell signal strength becomes stronger than a threshold.
  • Event A5 may traditionally be triggered when a current serving cell signal strength becomes weaker than a first threshold and a neighbor cell signal strength becomes stronger than a second threshold.
  • the handover restraining criterion based on signal quality (such as SNR) may be used as a further condition before sending a triggered measurement report for Events A3-A5.
  • the UE may send fewer of these types of triggered measurement reports and reduce the occurrence of handovers.
  • an example handover restraining criterion may be based on a cell blacklist or cell whitelist provided by the base station.
  • the base station may provide a cell blacklist, a cell whitelist, or both, in the measurement configuration.
  • the base station may generate the cell blacklist or cell whitelist based on a history of handover events in a particular area or between particular cells.
  • the base station may determine the cell blacklist or cell whitelist based on a deployment characteristic, such as the proximity of cells in a geography.
  • the UE may send a triggered measurement report for neighbor cells that are identified in the cell whitelist.
  • the UE may refrain from sending a triggered measurement report for neighbor cells that are identified in the cell blacklist.
  • Excessive handovers may cause interruptions to connectivity.
  • the interruptions may introduce latency during a handover event, may reduce throughput or otherwise may decrease user satisfaction with the network performance.
  • the techniques in this disclosure may mitigate excessive handovers by introducing additional criteria before a triggered measurement report is sent.
  • the additional criteria may prevent a triggered measurement report that would otherwise result in an undesirable handover from being sent.
  • one aim of this disclosure is to maintain an existing connection when the UE is not moving or when the signal quality of a neighbor cell does not justify a handover.
  • the techniques in this disclosure may reduce latency, increase data throughput, and improve user satisfaction.
  • FIG. 1 is a block diagram conceptually illustrating an example of a wireless communication system 100.
  • the wireless communication system 100 may include an LTE RAN or some other RAN, such as a 5G or NR RAN.
  • the wireless communication system 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS llOd) and other network entities.
  • a BS is an entity that communicates with user equipment (UEs) and also may be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB), an access point, a transmit receive point (TRP), or the like.
  • Each BS may provide communication coverage for a particular geographic area.
  • the term “cell” can refer to a coverage area of a BS, a BS subsystem serving this coverage area, or a combination thereof, depending on the context in which the term is used.
  • a UE may communicate with a base station via the downlink (DL) and uplink (UL).
  • the DL (or forward link) refers to the communication link from the BS to the UE
  • the UL (or reverse link) refers to the communication link from the UE to the BS.
  • a BS may provide communication coverage for a macro cell, a pico cell, a femto cell, another type of cell, or a combination thereof.
  • a macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription.
  • a pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription.
  • a femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, UEs in a closed subscriber group (CSG)).
  • a BS for a macro cell may be referred to as a macro BS.
  • a BS for a pico cell may be referred to as a pico BS.
  • a BS for a femto cell may be referred to as a femto BS or a home BS.
  • a BS 110a may be a macro BS for a macro cell 102a
  • a BS 110b may be a pico BS for a pico cell 102b
  • a BS 110c may be a femto BS for a femto cell 102c.
  • a BS may support one or multiple (for example, three) cells.
  • eNB base station
  • NR BS NR BS
  • gNB gNode B
  • 5GNB 5GNB
  • cell may be used interchangeably herein.
  • a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS.
  • the BSs may be interconnected to one another as well as to one or more other BSs or network nodes (not shown) in the wireless communication system 100 through various types of backhaul interfaces, such as a direct physical connection, a virtual network, or a combination thereof using any suitable transport network.
  • the wireless communication system 100 also may include relay stations.
  • a relay station is an entity that can receive a transmission of data from an upstream station (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, a UE or a BS).
  • a relay station also may be a UE that can relay transmissions for other UEs.
  • a relay station 1 lOd may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d.
  • a relay station also may be referred to as a relay BS, a relay base station, or a relay, among other examples.
  • the wireless communication system 100 may include a heterogeneous network that includes BSs of different types, for example, macro BSs, pico BSs, femto BSs, relay BSs, among other examples. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless communication system 100.
  • macro BSs may have a high transmit power level (for example, 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, 0.1 to 2 Watts).
  • a network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs.
  • the network controller 130 may communicate with the BSs via a backhaul.
  • the BSs also may communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.
  • UEs 120 may be dispersed throughout wireless communication system 100, and each UE may be stationary or mobile.
  • a UE also may be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, or a station, among other examples.
  • a UE may be a cellular phone (for example, a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (for example, smart ring, smart bracelet)), an entertainment device (for example, a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.
  • PDA personal digital assistant
  • WLL wireless local loop
  • Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs.
  • MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, among other examples, that may communicate with a base station, another device (for example, remote device), or some other entity.
  • a wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link.
  • Some UEs may be considered Intemet-of-Things (IoT) devices or may be implemented as NB-IoT (narrowband internet of things) devices.
  • Some UEs may be considered a Customer Premises Equipment (CPE).
  • UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, similar components, or a combination thereof.
  • any number of RANs may be deployed in a given geographic area.
  • Each RAN may support a particular RAT and may operate on one or more frequencies.
  • a RAT also may be referred to as a radio technology, an air interface, among other examples.
  • a frequency also may be referred to as a carrier, a frequency channel, among other examples.
  • Each frequency may support a single RAT in a given geographic area in order to avoid interference between RANs of different RATs.
  • NR or 5G RANs may be deployed.
  • 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface.
  • the 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with a ultra-high density (such as ⁇ 1M nodes/km 2 ), ultra-low complexity (such as ⁇ 10s of bits/sec), ultra-low energy (such as -10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (such as -99.9999% reliability), ultra-low latency (such as - 1 millisecond (ms)), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (such as - 10 Tbps/km 2 ), extreme data rates (such as multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.
  • IoTs Internet of things
  • the 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility.
  • TTI transmission time interval
  • TTI transmission time interval
  • TTI transmission time interval
  • TTI transmission time interval
  • TTI transmission time interval
  • TTI transmission time interval
  • TTI transmission time interval
  • subcarrier spacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and the like bandwidth (BW).
  • BW bandwidth
  • subcarrier spacing may occur with 30 kHz over 80/100 MHz BW.
  • the subcarrier spacing may occur with 60 kHz over a 160 MHz BW.
  • subcarrier spacing may occur with 120 kHz over a 500 MHz BW.
  • the scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency.
  • QoS quality of service
  • 5G NR also contemplates a self-contained integrated subframe design with UL/downbnk scheduling information, data, and acknowledgement in the same subframe.
  • the self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downbnk that may be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet the current traffic needs.
  • access to the air interface may be scheduled, where a scheduling entity (for example, a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity’s service area or cell.
  • a scheduling entity for example, a base station
  • the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity.
  • Base stations are not the only entities that may function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (for example, one or more other UEs). In this example, the UE is functioning as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication.
  • a UE may function as a scheduling entity in a peer-to-peer (P2P) network, in a mesh network, or another type of network. In a mesh network example, UEs may optionally communicate directly with one another in addition to communicating with the scheduling entity.
  • P2P peer-to-peer
  • mesh network UEs may optionally communicate directly with one another in addition to communicating with the scheduling entity.
  • a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.
  • two or more UEs 120 may communicate directly using one or more sidelink channels (for example, without using a base station 110 as an intermediary to communicate with one another).
  • the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (which may include a vehicle-to- vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or similar protocol), a mesh network, or similar networks, or combinations thereof.
  • V2X vehicle-to-everything
  • the UE 120 may perform scheduling operations, resource selection operations, as well as other operations described elsewhere herein as being performed by the base station 110.
  • FIG. 2 is a block diagram conceptually illustrating an example 200 of a base station 110 in communication with a UE 120.
  • the base station 110 and the UE 120 may respectively be one of the base stations and one of the UEs in wireless communication system 100 of Figure 1.
  • Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T > 1 and R
  • a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (for example, encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs.
  • MCS modulation and coding schemes
  • CQIs channel quality indicators
  • the transmit processor 220 also may process system information (for example, for semi-static resource partitioning information (SRPI) or the like) and control information (for example, CQI requests, grants, upper layer signaling, among other examples.) and provide overhead symbols and control symbols.
  • SRPI semi-static resource partitioning information
  • the transmit processor 220 also may generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS)) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS)).
  • a transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (for example, for OFDM) to obtain an output sample stream.
  • Each modulator 232 may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal.
  • T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.
  • the synchronization signals can be generated with location encoding to convey additional information.
  • antennas 252a through 252r may receive the downlink signals from base station 110 or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively.
  • Each demodulator 254 may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples.
  • Each demodulator 254 may further process the input samples (for example, for OFDM) to obtain received symbols.
  • a MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.
  • a receive processor 258 may process (for example, demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller or processor (controller/processor) 280.
  • a channel processor may determine RSRP, RSSI, RSRQ, channel quality indicator (CQI), among other examples.
  • one or more components of UE 120 may be included in a housing.
  • a transmit processor 264 may receive and process data from a data source 262 and control information (for example, for reports including RSRP, RSSI, RSRQ, CQI, among other examples) from controller/processor 280. Transmit processor 264 also may generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (for example, for DFT-s-OFDM, CP-OFDM, among other examples), and transmitted to base station 110.
  • control information for example, for reports including RSRP, RSSI, RSRQ, CQI, among other examples
  • Transmit processor 264 also may generate reference symbols for one or more reference signals.
  • the symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (for example, for DFT-s-OFDM, CP-OFDM, among other examples),
  • the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120.
  • Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller or processor (i.e., controller/processor) 240.
  • the base station 110 may include a communication unit 244 and may communicate to the network controller 130 via the communication unit 244.
  • the network controller 130 may include a communication unit 294, a controller or processor (i.e., controller/processor) 290, and memory 292.
  • the controller/processor 240 of base station 110, the controller/processor 280 of UE 120, or any other component(s) of Figure 2 may perform one or more techniques associated with managing measurement gap behavior of the first connection based on an operating attribute of the second connection, as described in more detail elsewhere herein.
  • the controller/processor 280 of UE 120, or any other component(s) (or combinations of components) of Figure 2 may perform or direct operations of, for example, processes 600, 700, 800 1001 or 1002 of Figures 6, 7, 8, 10A or 10B, respectively, or other processes as described herein.
  • the memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively.
  • the stored program codes when executed by the controller/processor 280 or other processors and modules at UE 120, may cause the UE 120 to perform operations described with respect to processes 600, 700, 800, 1001 or 1002 of Figures 6, 7, 8, 10A or 10B, respectively, or other processes as described herein.
  • a scheduler 246 may schedule UEs for data transmission on the downlink, the uplink, or a combination thereof.
  • FIG. 3 shows a block diagram conceptually illustrating an example wireless communication system 300 in which a UE may have dual connectivity (DC).
  • the wireless communication system 300 includes a UE 120, an LTE RAN 320, a 5GNR RAN 360, an EPC 330, and a packet network 340.
  • the UE 120 may include components (not shown), such a wireless communication module and a connection controller, among other examples.
  • a single chip or component of the UE 120 may provide the wireless communication module and the connection controller and may communicate via one or more radio components of the UE 120.
  • the wireless communication module may be capable of establishing an LTE connection (anchor connection) with an eNB 310 of the LTE RAN 320 and establishing a 5GNR connection (secondary connection) with a gNB 350 of the 5GNR RAN 360.
  • an LTE connection anchor connection
  • 5GNR connection secondary connection
  • the UE 120 may refer to a portable electronic device or to one or more components of the portable electronic device.
  • the LTE RAN 320 may be an evolved universal terrestrial radio access network (E- UTRAN) and is just one example RAT that may be used for an access stratum of the wireless communication system 300.
  • the EPC 330 is just one example of a core network that may be used in a non-access stratum of the wireless communication system 300.
  • the 5G NR RAN 360 may use the same EPC 330 as the LTE RAN 320.
  • the 5G NR RAN 360 may use a 5G Core (5GC) 370 with a 5G Core Access and Mobility Management Function (AMF) that performs similar functionality as the Mobility Management Entity (MME) 335 of the EPC 330.
  • the 5GC 370 may connect to the packet network 340.
  • the same packet network 340 may provide access to services such as Internet access, an IP multimedia subsystem (IMS) service, or other services.
  • IMS IP multimedia subsystem
  • FIG. 3 is described with reference to an E- UTRAN - NR dual connectivity (EN-DC) configuration in which the LTE RAN 320 and the NR RAN 360 utilize the same EPC 330 of the wireless communication system 300.
  • the LTE RAN 320 and the 5G NR RAN 360 may be used to establish multiple radio connections with the same UE 120.
  • the UE 120 may establish a first radio connection (LTE connection 312) with an eNB 310 of the LTE RAN 320. Establishing the first radio connection may include the UE 120 sending an RRC Setup Request message to the eNB 310 and receiving an RRC Setup message from the eNB 310.
  • the UE may setup a default packet bearer to the EPC 330.
  • the UE 120 may send an attach request message to the MME 335 in the EPC 330.
  • the MME 335 may respond with an attach accept message that sets up the default packet bearer.
  • the default packet bearer may be referred to as a default EPS bearer and may be used to communicate with the MME 335 or other elements in the EPC 330.
  • the default packet bearer may be used to setup other bearers or services provided by the wireless communication system 300.
  • the UE may send packet data via the default packet bearer to a data packet gateway (P-GW) 345 in the EPC 330 that connects to the packet network 340.
  • P-GW data packet gateway
  • the UE 120 may establish a second radio connection (5G NR connection 352) with a gNB 350 of the 5G NR RAN 360.
  • the second radio connection may be established by the wireless communication system.
  • the eNB 310 may determine that the UE 120 is authorized to utilize EN-DC and may activate a bearer via the gNB 350.
  • the eNB 310 may send an RRC Connection Reconfiguration message to the UE 120 to inform the UE 120 of the second radio connection.
  • the UE 120 may be in an RRC connected mode that includes radio connections to both the eNB 310 and the gNB 350.
  • the eNB 310 may be referred to as a master node (MN).
  • the gNB 350 may be referred to as a secondary node (SN).
  • Each base station may operate multiple cells. In some traditional deployments, a base station may operate three (3) cells, but other quantities of cells may be deployed at a base station.
  • a master cell group MCG may include a primary cell (PCell) and zero or more secondary cells (SCells) of the eNB 310.
  • a secondary cell group SCG may include a primary SCG cell (PSCell) and zero or more secondary cells (SCells) of the gNB 350.
  • the UE 120 may perform neighboring cell measurements and measurement reporting.
  • the eNB 310 or the gNB 350 may provide a measurement configuration to the UE 120 in an RRC message.
  • the measurement configuration may include reporting criterion for triggering a measurement reporting event based on a signal measurement of a neighbor cell.
  • Several types of standard measurement reports are defined by the 3 GPP 38.331 technical standard. Three of the measurement reporting events (referred to as Event A3, Event A4, and Event A5) are described in several examples of this disclosure.
  • a measurement reporting event occurs when a corresponding reporting criterion is satisfied for a time period.
  • Event A3 triggers a measurement report when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than the SpCell by at least an offset amount.
  • Event A4 triggers a measurement report when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a threshold.
  • Event A5 triggers a measurement report when the SpCell becomes worse (such as weaker signal strength or lower signal quality) than a first threshold (thresholdl) and a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a second threshold (threshold2).
  • the SpCell may be the PCell or the PSCell.
  • the premise of these triggered measurement reports is for the UE 120 to inform the base station when a neighbor cell may provide a better service for the UE 120.
  • the base station may perform a handover to the neighbor cell.
  • the handover may include some network-side reconfiguration, such as transferring bearers and changing a registration status of the UE 120, as well as UE-to-network reconfiguration, such as the eNB 310 sending an RRC Connection Reconfiguration message to the UE 120.
  • the RRC Connection Reconfiguration message may include changes to the MCG or SCG as part of the handover.
  • a UE 120 may be within overlapping coverage areas of different base stations.
  • the signal strengths of a neighboring cell and a serving cell are similar (such as within 2 to 3 dB, or 1-5 dB, etc.)
  • Excessive handovers also may occur more frequently in 5G NR networks.
  • reliable handover mechanisms in urban environments remains a challenge.
  • network operators may deploy base stations and turn them on and off in a coordinated manner to save energy. As a result, radio channel conditions may change dramatically for the mobile users and so the neighboring cell list changes rapidly.
  • the UE experiences frequent ping- pong handovers.
  • the maximum cell number may reach about 1008 cells in each operating frequency and a cell transmits synchronization signal by SSB, in which the UE can detect many equivalent RSRP level cells by the characteristics of each directional SSB and significantly large 5G cell deployments.
  • the UE may trigger frequent ping-pong handover in mobility or by the UE itself in a direction change when the network configures a relatively low cell level hysteresis margin and measurement offset. This can increase both the UE and network signal message transmission loading, resulting in a decrease of UE performance such as throughput, latency, and power.
  • FIG. 4 shows a pictorial diagram conceptually illustrating an example of a UE experiencing a ping-pong situation with excessive handovers.
  • Figure 4 depicts a wireless communication system 400 similar to the wireless communication system 300 described with reference to Figure 3.
  • the wireless communication system 400 includes a UE 120 using EN-DC in which the UE 120 has an LTE connection 312 with an eNB 310 and a 5GNR connection 352 with a gNB 350.
  • the RRC configuration for the connections may include a measurement configuration with triggered measurement reporting events.
  • Each triggered measurement reporting event may have a reporting criterion and a set of configurable parameters.
  • the reporting criterion may be satisfied based on whether an inequality is met.
  • the reporting criterion and parameters for Event A3, Event A4, and Event A4 are further described with reference to Figure 8. However, as an example to illustrate a ping pong situation, Event A3 is briefly described here.
  • the inequality for entering Event A3 is as follows:
  • Mn is the measurement result of the neighboring cell, not taking into account any offsets.
  • Ocn is the cell specific offset of the neighbor cell, and set to zero if not configured for the neighbor cell.
  • Ocp is the cell specific offset of the SpCell, and is set to zero if not configured for the
  • Hys is the hysteresis parameter for this event.
  • Mn are expressed in dBm in case of RSRP, or in dB in case of RSRQ and RS- SINR.
  • Each of these variables may be indicated in the measurement configuration provided by a base station to the UE.
  • Either (or both) of the eNB 310 or the gNB 350 may provide a measurement configuration.
  • the measurement configuration may indicate a timeToTrigger parameter that indicates a time during which specific criteria for the event needs to be met in order to trigger a measurement report. Thus, the reporting criteria must be satisfied for the timeToTrigger time duration.
  • the Off may be set to 1 dB and the Hys also may be set to 1 dB.
  • the effect of the Off and the Hys in the inequality (1) may be disregarded since they equally adjust both sides of the inequality (1).
  • the effect of the Ofn, the Ofp, and the Ocp may not modify the outcome of the inequality (1).
  • the inequality (1) that triggers the Event A3 report may occur when the measurement result of the neighboring cell is greater than the measurement of the SpCell.
  • the UE 120 may periodically perform measurements of neighbor cells, such as other cells of gNB 350 or of another gNB 450.
  • the measurements of the neighbor cells may be close (such as within 1-2 dB, 1-5 dB, etc.) to the measurement of the SpCell.
  • the SpCell refers to either the PCell of the MCG or the PSCell of the SCG. Taking the SpCell of the SCG as an example, the UE 120 may compare the measurement results of the neighbor cell 452 of the gNB 450 with the measurement results of the existing PSCell used for the 5GNR connection 352 with the gNB 350.
  • the Event A3 report may be triggered.
  • the UE 120 may send the triggered Event A3 report to the gNB 450, causing the gNB 350 to reconfigure the RRC configuration to remove the serving cells of the gNB 350 from the SCG and instead make the neighbor cell 452 of the gNB 450 the PSCell of the updated SCG.
  • the gNB 350 may perform a handover from the gNB 350 to the gNB 450.
  • the UE 120 may discover that the Event A3 report is triggered again - this time indicating that the gNB 350 has a stronger measurement than the previous neighbor cell 452 (which has become the SpCell of the updated SCG). Thus, the UE 120 may send another Event A3 report (this time to the gNB 450), causing the gNB 450 to reconfigure the RRC again and perform a handover back to the gNB 350.
  • the cycle may continue repetitively while the UE 120 remains in a location where the signals from neighbor cells (such as from both the gNB 350 and the gNB 450) have similar measurement results repetitively triggering the inequality (1) for the Event A3 report.
  • the example of Figure 4 is described with reference to Event A3, a similar ping-pong situation may occur with the inequalities associated with Event A4 and Event A5.
  • a ping-pong situation may be detected based on a frequency of handovers in a recent time period.
  • the frequency of handovers may be determined based on n count of handovers triggered within a time duration tl.
  • the UE 120 may detect a ping-pong situation when, for example, there are at least four (4) handovers within an approximately 20 second duration. Excessive handovers may reduce downlink throughput and network performance. For example, the time associated with RRC reconfiguration may cause latencies and disrupt communication.
  • the UE 120 may use one or more techniques to suppress or further precondition the sending of triggered measurement reports.
  • the UE 120 may evaluate whether a handover restraining criterion is satisfied before sending a triggered measurement report.
  • the handover restraining criterion may limit the occurrence of triggered measurement reporting events that would otherwise result in a further handover.
  • FIG. 5 shows a signaling diagram illustrating a handover process 500.
  • the handover process 500 may include a first BS 110A, a second BS 110B, and a UE 120, which may be examples of the corresponding devices described with reference to Figures 1-4.
  • the handover process 500 may be implemented by the first BS 110A as a source BS serving the UE 120 in a serving cell (also referred to as a source cell), the second BS 110B as a target BS in a target cell, and a NR core network including a user plane function (UPF) component 502 and an access and mobility management function (AMF) component 504.
  • the source BS and the target BS are in communication with the core network for mobility support and user plane functions.
  • Steps of the handover process 500 can be executed by computing devices (such as, a processor, processing circuit, or other suitable component) of the source BS, the UE 120, the target BS, the UPF component 502, and the AMF component 504.
  • the handover process 500 includes a number of enumerated steps, but implementations of the handover process 500 may include additional steps before, after, and in between the enumerated steps. In some implementations, one or more of the enumerated steps may be omitted or performed in a different order.
  • the operations between the first BS 110A, second BS 110B, and the UE 120 may be transmitted in a different order than the example order shown, or the operations performed by the BSs 110 and the UE 120 may be performed in different orders or at different times. Certain operations also may be left out of the handover process 500, or other operations may be added to the handover process 500.
  • a handover between the first BS 110A and the second BS 110B is an inter-CU (centralized unit) handover, using a DC handover, in which both the first BS 110A and the second BS 110B are associated with a different CU.
  • the handover process 500 may commence at block 505 with the first BS 110A establishing a first connection with the UE 120 (such as, performing a cell acquisition procedure, a random access procedure, an RRC connection procedure, an RRC configuration procedure, etc.).
  • the UE may perform a measurement procedure that may include performing channel measurements.
  • Such may include, for example, signal measurements of neighboring BSs by the UE 120 to identify one or more neighboring BSs that may be candidates for the handover procedure.
  • the measurements may include a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSSI), or a signal-to-interference-noise-ratio (SINR), among other examples.
  • RSRP reference signal received power
  • RSRQ reference signal received quality
  • RSSI received signal strength indicator
  • SINR signal-to-interference-noise-ratio
  • the UE 120 may detect a measurement reporting event for which a reporting criterion is satisfied based on the signal measurements.
  • the measurement event may be a signal measurement (such as, a reference signal received power (RSRP)) of the first BS 110A dropping below a threshold value by a predetermined measurement offset, may be a time-based periodic event, or combinations thereof.
  • the measurement reporting event may be further regulated or restricted based on a handover restraining criterion.
  • the handover restraining criterion may be used in addition to the reporting criterion. Alternatively, or additionally, the handover restraining criterion may be based on overriding a parameter of the reporting criterion.
  • the UE 120 may transmit a measurement report to the first BS 110A, and the measurement report may indicate that the second BS 110B is a candidate BS for a handover.
  • the measurement report may include measurements about the quality of the channel between the UE and the source BS.
  • the UE 120 may send the measurement report indicating the measurement reporting event (such as, an A3 measurement report in the NR system).
  • the first BS 110A may consider that another better neighbor cell (such as, the second BS 110B) is detected if the A3 measurement report is received within a certain time from the UE 120.
  • a new measurement event (such as, an A3 measurement event) may be defined, which is to report when a neighbor cell is detected to be stronger than the first BS 110A and the second BS 110B.
  • the first BS 110A may make a handover decision to handover the UE 120 from the first BS 110A to the second BS 110B.
  • the first BS 110A may make the handover decision based on the measurement report provided by the UE 120, one or more threshold values for initiating a handover, a differential in one or more signal measurements from one or more prior measurement reports, one or more measurement reports from other UEs, or any combinations thereof.
  • the first BS 110A may coordinate with the second BS HOB to prepare for a handover (HO), for example, based on the measurement report indicating that the signal quality of the first BS 110A is lesser than the signal quality of the second BS HOB.
  • HO handover
  • the first BS 110A may request the second BS 110B to prepare for the handover.
  • the first BS 110A may communicate the UE’s radio resource control (RRC) context information or other UE’s configurations to the second BS 110B.
  • the second BS 110B may prepare for the handover by reserving resources for the UE 120. After reserving the resources, the second BS 110B may transmit an acknowledgement to the first BS 110A in response to the handover request.
  • RRC radio resource control
  • the first BS 110A may determine that the UE 120 is to be handed over to the second BS 110B. Further, the first BS 110A may determine that the UE 120 has a dual-connectivity (DC) capability and may generate a decision to perform a DC-based handover of the UE 120. For example, the first BS 110A (or an associated CU) may select from possible handover procedures that may be performed by UE 120 based at least in part on the indicated capability of UE 120. In the example of Figure 5, the first BS 110A may select an DC handover procedure for UE 120 based at least in part on UE 120 indicating a DC capability. In other examples, the first BS 110A may select a make-before-break handover procedure or a different handover procedure (such as, a legacy handover procedure), and different operations associated with the selected handover procedure may be performed.
  • DC dual-connectivity
  • the first BS 110A and the second BS 110B may initiate a role switch negotiation procedure.
  • the first BS 110A may transmit a role switch request to the second BS 110B.
  • the role switch request may indicate that the second BS HOB is to switch to be the master node in the DC connection with the UE 120 once the connection between the UE 120 and the second BS is established, and the first BS 110A is to switch to be the SN connection.
  • the second BS HOB may receive the role switch request and identify that the UE 120 is to be handed over to the second BS HOB, and transmit a role switch acknowledgment at block 540.
  • the first BS 110A may transmit a secondary node (SN) addition request to the second BS HOB.
  • the SN addition request may be provided based on the DC handover decision to establish a DC connection between both the first BS 110A and the second BS HOB and the UE 120.
  • the initial connection between the first BS 110A and the UE 120 in such cases is a master node (MN) connection and the second BS HOB may be added initially as a SN based on the SN addition request.
  • MN master node
  • the second BS HOB may transmit a SN addition acknowledgment to the first BS 110A to acknowledge that the second BS HOB received, and that may indicate an ability to serve UE 120 after the handover procedure.
  • the role switch request may be combined with the SN addition request, and the role switch acknowledgment may be combined with the SN addition acknowledgment. In such cases, signaling between the first BS 110A and the second BS 110B may be reduced.
  • the role switch request and the role switch acknowledgment may be optional operations, and may be skipped in cases where the SN addition request also includes the role switch request, and the SN addition acknowledgment also includes the role switch acknowledgment.
  • the first BS 110A may transmit a RRC reconfiguration message to the UE 120.
  • the RRC reconfiguration message may include a handover command instructing the UE 120 to handover from the first BS 110A to the second BS 110B, in which a handover execution phase begins.
  • the handover command may include information associated with the second BS 110B, for example, a random access channel (RACH) preamble assignment for accessing the second BS 110B.
  • RACH random access channel
  • the UE 120 may execute the handover by performing a random access procedure with the second BS 110B.
  • the RRC reconfiguration message may indicate to the UE 120 that a connection with the second BS 110B is to be established according to a DC connection establishment procedure.
  • the RRC reconfiguration may indicate that UE 120 is to perform DC handover procedure with second BS 110B using the DC capability of UE 120.
  • the RRC reconfiguration can include information identifying second BS 110B, information identifying a handover configuration, identifying a DC configuration, or combinations thereof.
  • the RRC reconfiguration message may provide an indication of a secondary cell group associated with the second BS 110B that is to be configured as part of the DC based handover, and also indicate the source cell group identification of the first BS 110A.
  • downlink data that is to be transmitted to the UE 120 may be provided to the first BS 110A (such as, from the UPF component 502 at the core network), and the first BS 110A may transmit the downlink data to the UE 120 via the first connection.
  • uplink data transmitted from the UE 120 may be transmitted to the first BS 110A via the first connection.
  • the first BS 110A may forward downlink user data to the second BS 110B.
  • the UE 120 may configure a SN based on the RRC reconfiguration based on a DC connection procedure, and may transmit an RRC reconfiguration complete indication to the first BS 110A to indicate that the second connection is being established.
  • the UE 120 may maintain the first connection with the first BS 110A, and thus have an active established connection during the handover, as indicated at block 597.
  • the first BS 110A may transmit a SN reconfiguration complete indication to the second BS HOB that may indicate that the UE 120 is configuring the second connection.
  • the UE 120 and the second BS 110B may perform a random access procedure to establish a second connection with the second BS 110B.
  • the random access procedure may be performed according to established random access procedures (such as,
  • the UE 120 may, at block 555, transmit a RRC reconfiguration complete indication to the second BS 110B.
  • the second BS 110B may be the master node in the DC connection with both the first BS 110A and second BS 110B, and thus the second connection is the primary link as indicated at block 560.
  • the UE 120 may transmit a packet data convergence protocol (PDCP) status transfer and uplink user data to the second BS 110B via the second connection.
  • PDCP packet data convergence protocol
  • the UE 120 may perform uplink user/control plane duplication with the first BS 110A. For example, control plane data may be duplicated and shared between the first BS 110A and the second BS 110B. Accordingly, UE 120 may achieve improved reliability when receiving the data on the downlink.
  • the second BS HOB may transmit a role switch complete indication to the first BS 110A.
  • the role switch complete indication may provide an indication to the first BS 110A (such as, via an Xn backhaul link) that the second connection has been established with the UE 120, and that signaling radio bearers (SRBs) and data radio bearers (DRBs) have been established in the second connection.
  • the first BS 110A may transmit a SN status transfer to the second BS 110B. The SN status transfer may provide the most up to date PDCP status and downlink sequence number to use, for example.
  • the SN status transfer also may indicate to the second BS HOB that the first connection with the first BS 110A may be released in accordance with the DC handover procedure.
  • the second BS 110B may generate a handover complete decision and determine that the first connection with the first BS 110A may be released.
  • the second BS HOB responsive to determining that the handover is complete, may transmit a RRC reconfiguration request to the UE 120 to release the first connection with the first BS 110A.
  • the second BS HOB may provide a handover completion indication to the UPF component 502 in the core network. Additionally or alternatively, the second BS HOB may transmit a PDCP status transfer to the UE 120.
  • the UE 120 may release the first connection with the first BS 110A.
  • the UE 120 may release the first connection, for example, by removing DRBs and SRBs associated with the first BS 110A, and PDCP status and sequence numbers associated with the first connection. [0088] At block 590, the UE 120 may transmit a RRC reconfiguration complete indication to the second BS 110B to indicate that the first connection has been released.
  • the second BS 110B, the UPF component 502, and the AMF component 504 may coordinate to switch the user-plane (U-plane) path of the UE 120 from the first BS 110A to the second BS 110B. Until this point of time, the DL data transmission for the UE 120 is still being routed to the first BS 110A.
  • the second BS 110B may transmit a path switch request to the AMF component 504 of the core network, and the AMF component 504 and the UPF component 502 may perform a path switch related to core network internal signaling to provide the actual downlink path used to the UPF for subsequent downlink data transmissions.
  • the first BS 110A may transmit the fresh downlink data to the second BS 110B for downlink transmission to the UE 120.
  • the AMF component 504 may provide a path switch request acknowledgment to the second BS 110B.
  • the second BS 110B may transmit a UE context release command to the first BS 110A, and the first BS 110A may release UE context for the first connection and transmit a UE context release complete back to the second BS 110B.
  • the AMF component 504 transmits an end mark message to the first BS 110A after the U-plane path is switched.
  • the AMF component 504 may provide an end marker to the first BS 110A to indicate that the downlink path has been changed to the second BS HOB, and the first BS 110A may provide an indication to the second BS 110B that the end marker has been received.
  • UE 120 may use a dual protocol stack, which includes a source protocol stack for communicating with first BS 110A and a target protocol stack for communicating with second BS 110B.
  • Each of these protocol stacks may include a PDCP layer, a radio link control (RLC) layer, a medium access control (MAC) layer, or a physical (PHY) layer.
  • the source protocol stack and the target protocol stack may share one or more layers, such as a PDCP layer.
  • the target protocol stack may be used for uplink data transmissions.
  • Figures 6-11 describe example operations for processes that utilize handover restraining criterion in addition to (or as modification of) a reporting criterion.
  • the example operations of the processes may be implemented by a UE or its components as described herein.
  • the processes described with reference to Figures 6-11 may be performed by an apparatus such as UE 120 described with reference to Figures 1-5 or a wireless communication device such as the wireless communication device 1400 described with reference to Figure 14.
  • Figure 6 shows a flowchart illustrating an example process for triggered measurement reports using a handover restraining criterion.
  • the apparatus may establish at least a first connection with a serving cell of a base station (BS).
  • BS base station
  • the apparatus may receive a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based, at least in part, on one or more network-provided parameters and a signal measurement of a neighbor cell, wherein the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell.
  • a reporting criterion for a measurement reporting event the reporting criterion configured to trigger the UE to send a triggered measurement report based, at least in part, on one or more network-provided parameters and a signal measurement of a neighbor cell, wherein the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell.
  • the apparatus may monitor for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based, at least in part, on a UE-configured parameter different from the one or more network-provided parameters.
  • the apparatus may communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • the handover restraining criterion may be one or more of the examples described herein, including any combination thereof.
  • the apparatus may send the triggered measurement report when it determines that both the reporting criterion and the handover restraining criterion have been satisfied.
  • the handover restraining criterion may limit the triggered measurement reports that would otherwise be sent using the reporting criterion.
  • the handover restraining criterion is based on a modification to the reporting criterion to override a parameter (such as a measurement offset value) of the reporting criterion.
  • Figure 7 shows a flowchart illustrating an example process 700 with example handover restraining criteria.
  • the apparatus may determine a signal measurement of a neighbor cell.
  • the signal measurement may be an RSRP, RSRQ or SINR of the neighbor cell.
  • the apparatus may determine if the signal measurement satisfies a reporting criterion for a measurement reporting event. If the signal measurement does not satisfy the reporting criterion, the process may return to block 710 to check another signal measurement or another neighbor cell. If the signal measurement does satisfy the reporting criterion, the process may continue to block 730. [0101] At block 730, the apparatus may determine a handover restraining criterion. In some implementations, the handover restraining criterion may depend on whether a ping-pong situation has been detected. A ping-pong situation may be detected with a frequency of handovers is above a threshold.
  • apparatus may determine whether the frequency of handovers falls within a high frequency category, a medium frequency category, or a normal frequency category.
  • the frequency of handovers (or the high frequency category, medium frequency category, or normal frequency category) may impact which handover restraining criteria are used in block 730 or configurable parameters of a handover restraining criterion.
  • the apparatus may determine the frequency of handovers.
  • the handover restraining criterion may be based on a delay timer. The delay timer is different from the timeToTrigger parameter which is associated with a measurement configuration for an Event.
  • the delay timer is used prevent a new measurement report from being sent for a time period since a last handover event.
  • the duration of the delay timer may depend on the frequency of handovers.
  • the handover restraining criterion may be satisfied when the delay timer expires.
  • the delay timer may be implemented as a countdown timer that is initiated after a previous handover. When the countdown timer reaches zero the delay timer is expired and the handover restraining criterion is satisfied.
  • the handover restraining criterion may be based on a signal quality comparison.
  • handover restraining criterion may require the signal quality of the neighbor cell to be better (such as a higher quality) than the signal quality of the SpCell by at least a threshold amount and for a time period.
  • the handover restraining criterion may be satisfied when the neighbor cell’s signal quality is at or above the threshold amount for the time period.
  • the handover restraining criterion may be based on a signal quality precondition.
  • the handover restraining criterion may be satisfied when the signal quality of the neighbor cell is better (such as a higher quality) than a signal quality threshold for a time period.
  • the handover restraining criterion may be based on UE movement.
  • the handover restraining criterion may be satisfied or relaxed when the UE determines that the UE is changing location relative to a base station. For example, when the UE is moving (such as changing locations), the handover restraining criterion may easier to satisfy than when the UE is stationary.
  • a movement speed (such as a rate of distance traveled over time) may impact the handover restraining criterion.
  • a duration of the delay timer may depend on the movement speed. The duration may be set to a first value when the UE stationary, set to a second value when the UE is non-stationary and the movement speed of the UE is lower than a speed threshold, or set to a third value when the UE is non-stationary and the movement speed of the UE is higher than the speed threshold. The second value may be lower than the first value and the third value lower than the second value.
  • the duration of the delay timer may decrease as the movement speed of the UE increases.
  • a parameter (such as a signal measurement offset value) of the handover restraining criterion may be adjusted based on the movement speed of the UE.
  • a higher signal measurement offset value may restrain more handovers and may be used when the movement speed of the UE is lower than the speed threshold.
  • a lower signal measurement offset value may restrain less handovers and may be used when the movement speed of the UE is higher than the speed threshold lower.
  • the apparatus may determine the UE movement and determine which, if any, of the handover restraining criteria in block 730 to use.
  • the operations of block 730 and the use of a handover restraining criterion may be dependent on a determination that the UE is stationary.
  • the apparatus may determine whether the handover restraining criterion is satisfied. If the handover restraining criterion is satisfied, the process 700 continues to block 795 in which the apparatus may send the triggered measurement report. Otherwise, if the handover restraining criterion is not satisfied, the process 700 may return to block 710.
  • Figure 8 shows a flowchart illustrating an example process 800 using a combination of handover restraining criteria.
  • the example handover restraining criteria in Figure 6 may be combined or structured in an order.
  • the frequency of handovers and the UE movement may be used to determine the duration of a delay timer.
  • the example process 800 provides an example combination and structure of multiple handover restraining criteria.
  • the apparatus may determine a frequency of handovers.
  • the frequency of handovers may be a count n of handovers triggered during a time period t.
  • the apparatus may determine a duration of a delay timer based on the frequency of handovers.
  • the duration of the delay timer may increase linearly or exponentially in relation to the frequency of handovers.
  • the duration of the delay timer may be from 1-20 seconds (s).
  • the apparatus may determine a high duration (such as 20 s) for the delay timer if the frequency of handovers fall in a high frequency category (such as more than 6 handovers in the preceding 5 s).
  • the apparatus may determine a medium duration (such as 10 s) for the delay timer if the frequency of handovers fall in the medium frequency category (such as 2-5 handovers in the preceding 5 s).
  • the apparatus may determine a zero or nominal duration (such as 1 s) for the delay timer if the frequency of handovers fall in the normal frequency category (such as less than 2 handovers in the preceding 5 s).
  • the values of the delay timer durations and thresholds for the handover frequency categories may be configurable parameters.
  • the thresholds for the handover frequency categories may be expressed as an average or running average. For example, UE may determine the frequency of handovers an average ratio of handovers over a time period.
  • the high frequency category may refer to an average of more than 1 handover per second.
  • the medium frequency category may refer to an average of approximately 1 handover per second (or a range such as 0.5-1.5 handovers per second).
  • the normal frequency category may refer to an average of less than approximately 1 handover per second.
  • the UE may determine that the frequency of handovers is in the high frequency category after consecutive instances of utilizing the delay timer duration associated with the medium frequency category.
  • the apparatus may determine a change in signal strength for the current serving cell (such as the SpCell). For example, the apparatus may determine the current RSRP, current RSSI, or current SINR measured for the current serving cell and compare it to a previous corresponding measurement for the current serving cell.
  • the apparatus may determine the current RSRP, current RSSI, or current SINR measured for the current serving cell and compare it to a previous corresponding measurement for the current serving cell.
  • the apparatus may determine whether the change in signal strength indicates the UE is moving. For example, when the UE is changing locations relative to a base station, the RSRP, RSSI, or SINR also may change. A change in the RSRP, RSSI, or SINR may be used to infer whether the UE is moving. When the change or variation of the signal strength is above a signal strength change threshold, the apparatus may infer that the UE is moving. Conversely, when the change or variation of the signal strength is below the signal strength change threshold, the apparatus may infer that the UE is stationary. If the UE is moving, the process 800 may continue to block 860. If the UE is stationary, the process 800 may continue to block 850.
  • the apparatus may start a delay timer after a handover event.
  • the duration of the delay timer is the duration determined in block 820.
  • the delay timer will be a handover restraining criterion that prevents the apparatus from sending a triggered measurement report until after the delay time expires.
  • the apparatus may send a triggered measurement report.
  • the apparatus may disable the delay timer or reduce the duration of the delay timer.
  • block 860 is performed when the UE is moving.
  • the usefulness of performing a handover may outweigh the advantage of using a handover restraining criterion to prevent a handover.
  • Figure 9 shows a diagram illustrating an example of a signal measurement plot over time and corresponding behavior to enable or disable a handover restraining criterion.
  • the handover restraining criterion may be enabled (to restrict excessive handovers) when a signal measurement of the serving cell is above a first signal strength threshold 910 (referred to as “RSRP High Threshold” in some examples).
  • the handover restraining criterion may be disabled (for more permissive handover behavior) when a signal measurement of the serving cell is below a second signal strength threshold 920 (referred to as “RSRP Low Threshold” in some examples).
  • the first signal strength threshold 910 and the second signal strength threshold 920 may provide a hysteresis range during which changes to the handover restraining criterion may be kept stable to prevent frequent enablement or disablement.
  • the received signal measurement plot 900 includes a signal measurement 902 of a transmission signal from a BS.
  • the signal measurement plot 900 indicates that the signal measurement 902 varies in RSRP values over time.
  • the signal measurement 902 has an RSRP value that is greater than the first signal measurement threshold 910.
  • the UE may enable the handover restraining criterion.
  • enabling the handover restraining criterion may include overriding a network- provided parameter (such as an offset value in the reporting criterion) with a higher value.
  • the handover restraining criterion may be enabled for at time period (shown as box 904) between time A and time B.
  • the UE may disable the handover restraining criterion (shown at arrow 906).
  • the handover restraining criterion may be disabled for at time period (shown as box 909) between time B and time C.
  • the RSRP value of the signal measurement 902 begins increasing, until the RSRP value exceeds the first signal measurement threshold at time C.
  • the UE may once again enable the handover restraining criterion (shown at arrow 912).
  • the handover restraining criterion may be enabled for at time period (shown as box 908) from time C as long as the RSRP value of the signal measurement 902 remains above the second signal strength threshold 920.
  • the UE can avoid (or restrain) ping-pong handover when the RSRP value of the serving cell is greater than the RSRP High Threshold. Conversely, the UE can disable the handover restraining criterion to trigger a relatively fast measurement report when the RSRP value of the serving cell is lesser than the RSRP Low Threshold. At any time that the RSRP value of the serving cell is between the RSRP High Threshold and the RSRP Low Threshold, the UE may maintain the enablement or disablement state of the handover restraining criterion. Thus, the RSRP High Threshold and the RSRP Low Threshold may provide stability to prevent frequent enablement or disablement changes to the handover restraining criterion.
  • FIG. 10A shows a flow diagram of an example process 1001 for monitoring for an occurrence of a measurement reporting event.
  • the process 1001 starts at block 1010, where the UE enters a connected mode on aNR cell (such as, the BS 105).
  • the UE receives a measurement configuration from the BS.
  • the measurement configuration includes a reporting criterion for a measurement reporting event.
  • the reporting criterion may be based on one or more network-provided parameters (such as a first signal measurement offset).
  • the UE receives the measurement configuration in a radio resource control (RRC) message.
  • the measurement configuration instructs the UE to obtain signal measurements of a plurality of reference signals from a base station (BS) and one or more neighbor cells and send a triggered measurement report when the reporting criterion is satisfied.
  • RRC radio resource control
  • the UE determines whether a network-provided parameter in the reporting configuration needs to be changed.
  • the reporting criterion may include a first signal measurement offset (such as, A3 offset provided by the network for an A3 event configuration).
  • the UE may determine whether the A3_offset needs to be overridden with a different signal measurement offset (such as, a user-configurable override_A3_offset) in a handover restraining criterion.
  • the handover restraining criterion may act as an override of the reporting criterion when one or more parameters are changed to make the modified reporting criterion more stringent than the original reporting criterion.
  • the first signal measurement offset may be overridden with a higher value.
  • the decision in block 1016 may be based on how many handovers have been detected in over a recent time period. For example, if the UE is experiencing a ping-pong condition, the UE may decide that the network-provided parameter in the reporting configuration needs to be changed.
  • the UE may determine whether the A3_offset plus a hysteresis margin (such as 1 dB) is less than an override threshold value (such as 3 dB). As an example, if the A3_offset is 1 dB, then sum of the A3_offset and the hysteresis margin would be 2 dB, which is less than the 3 dB override threshold value. In such case, the UE may decide that the network-provided parameter in the reporting configuration needs to be changed. If the decision in block 1016 is to change the network-provided parameter, the process continues to block 1020. Otherwise, if the decision is that the network-provided parameter does not need to be changed, the process continues to block 1030.
  • a hysteresis margin such as 1 dB
  • an override threshold value such as 3 dB
  • the UE may enable the handover restraining criterion.
  • the UE may determine the UE-configured parameter for the handover restraining criterion. For example, the UE may determine a second signal measurement offset (such as override_A3_offset) that will be used for the handover restraining criterion. The second signal measurement offset may be used to override the first signal measurement offset in the reporting criterion. The resulting modified reporting criterion may be referred to as the handover restraining criterion. From block 1022, the process continues to block 1040.
  • a second signal measurement offset such as override_A3_offset
  • the process continues to block 1030.
  • the UE may disable the handover restraining criterion.
  • the UE may use the network-provided parameter (such as A3_offset) and reporting criterion without the handover restraining criterion.
  • the UE may perform signal measurements and prepare for an event evaluation operation to detect an occurrence of the measurement reporting event.
  • the UE may monitor the signal measurement of the BS and neighbor cells over time.
  • the UE may evaluate the signal measurements based on the network-provided parameter (if the handover restraining criterion is disabled) or the UE- configured parameter (if the handover restraining criterion is disabled).
  • the UE may select whether to use the network-provided parameter or the UE- configured parameter based on a signal measurement of the serving cell, as described further with reference to Figure 10B).
  • the UE may determine whether a measurement reporting event is triggered based on the evaluation in block 1050. If the UE detects an occurrence of a measurement reporting event based on a comparison of the signal measurements between the BS and the one or more neighbor cells, the process continues to block 1090. If the UE does not detect an occurrence of the measurement reporting event, the process may return to block 1040 to periodically perform new signal measurements. Alternatively, or additionally, the process may return to block 1016 if the network-provided parameter is changed by a new measurement configuration following a handover or if the frequency of handovers changes.
  • FIG. 10B is a flow diagram of an example process 1002 of a measurement evaluation.
  • a UE may perform a measurement evaluation periodically while monitoring the signal measurements.
  • the example process 1002 may correspond to block 1050 described with reference to Figure 10A.
  • the UE may determine whether the first signal measurement offset (A3_offset) is overridden by the second signal measurement offset (override_A3_offset).
  • the UE may determine which signal measurement offset to use based on a current signal measurement of the current serving cell.
  • the UE can streamline the measurement evaluation while adapting quickly to changed channel conditions.
  • the UE may obtain signal measurements of the serving cell and one or more neighbor cells.
  • the UE may determine whether the handover restraining criterion is enabled. If the UE determines that the handover restraining criterion is currently enabled, the process 1002 proceeds to block 1060. Otherwise, the process 1002 proceeds to block 1070.
  • the UE may determine whether the signal measurement (such as, RSRP value) of the current serving cell is less than the second signal strength threshold (such as, RSRP Low Threshold). If the UE determines that the RSRP value of the serving cell is less than the RSRP Low Threshold, the process 1002 proceeds to block 1062. Otherwise, the process 1002 proceeds to block 1066.
  • the signal measurement such as, RSRP value
  • the second signal strength threshold such as, RSRP Low Threshold
  • the UE may disable the handover restraining criterion because the RSRP value of the serving cell is less than the RSRP Low Threshold.
  • the UE may use the first signal measurement offset (such as A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the reporting criterion.
  • the first signal measurement offset may be the network-provided parameter originally obtained from the measurement configuration.
  • the UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • the UE may use the second signal measurement offset (such as override_A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the handover restraining criterion.
  • the UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
  • the process 1002 proceeds to block 1070.
  • the UE determines whether the RSRP value of the current serving cell is greater than the first signal strength threshold (such as, RSRP High Threshold). If the UE determines that the RSRP value is greater than the RSRP High Threshold, the process 1002 proceeds to block 1072. Otherwise, the process 1002 proceeds to block 1076.
  • the UE may enable the handover restraining criterion because the RSRP value of the serving cell is greater than the RSRP High Threshold.
  • the UE may use the second signal measurement offset (such as override_A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the handover restraining criterion.
  • the second signal measurement offset may be a UE-configured parameter that is different from the network-provided parameter originally obtained from the measurement configuration.
  • the UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
  • the UE may use the first signal measurement offset (such as A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the reporting criterion.
  • the first signal measurement offset may be the network-provided parameter originally obtained from the measurement configuration.
  • the UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • Figure 11 shows example measurement reporting events 1100 based on combinations of their respective reporting criterion and a handover restraining criterion.
  • the example measurement reporting events 1100 include a modified Event A3 1110, a modified Event A4 1140, and a modified Event A5 1170.
  • each of the example measurement reporting events 1100 is shown in association with their reporting criterion on the left side of the Figure 11 and an example handover restraining criterion on the right side of the Figure 11.
  • the reporting criterion 1120 for Event A3 is traditionally triggered when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) by an offset amount over the SpCell.
  • the modified Event A3 1110 may be triggered based on a combination of the reporting criterion 1120 and a handover restraining criterion, such as the example handover restraining criterion 1130.
  • the example handover restraining criterion 1130 is satisfied when the neighbor signal quality (such as SNR) becomes higher than the signal quality of the SpCell by an offset amount for a time window T.
  • Inequality (1) may be used to determine when the reporting criterion 1120 is satisfied and inequality (2) may be used to determine when the example handover restraining criterion 1130 is satisfied. Inequality (1) is restated below in relation to an inequality (2) for the example handover restraining criterion 1130.
  • Mn + Ofin + Ofin - Hys > Mp + Ofp + Ocp +Off (for duration of timeToTrigger) (1)
  • SNR of Mn > SNR of Mp + ThresholdSNR (for time window T) (2)
  • the ThresholdSNR may be a configurable parameter, such as 2-3 dBs. Inequality (2) is satisfied when the SNR of the neighbor cell is higher by at least ThresholdSNR over the SNR of the SpCell.
  • Event A4 is traditionally triggered when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a threshold.
  • the reporting criterion 1150 for Event A4 is satisfied when a neighbor cell becomes stronger or higher a threshold ( Thresh ) value and an offset amount that is set in the measurement configuration.
  • Thresh a threshold
  • Inequality (3) may be used to determine when the reporting criterion 1150 for the Event A4 triggered report 1140 is satisfied.
  • the Thresh value is in the same unit as the Mn. so the unit will be dBm in case of RSRP or dB in case of RSRQ and RS-SINR.
  • the other variables, Mn , Ofn. Ocp, and Hys. are the same as described with reference to Event A3.
  • the modified Event A4 1140 may be triggered based on a combination of the reporting criterion 1150 and a handover restraining criterion, such as the example handover restraining criterion 1160.
  • the example handover restraining criterion 1160 is satisfied when the neighbor signal quality (such as SNR) becomes higher than a threshold and an offset amount for a time window T.
  • Inequality (3) may be used to determine when the reporting criterion 1150 is satisfied and inequality (4) may be used to determine when the example handover restraining criterion 1160 is satisfied.
  • the ThresholdSNR may be a configurable parameter, such as 2-3 dBs.
  • Event A5 is traditionally triggered when the SpCell becomes worse than a first threshold ( Threshl ) and a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a second threshold (Threshl).
  • Threshl and Thresh2 are parameters provided by the base station in the measurement configuration.
  • the other variables, Mp, Hys, Mn, Ofn, Ocn, and Hys, are the same as described with reference to Event A3.
  • the modified Event A5 1170 may be triggered based on a combination of the reporting criterion 1170 and a handover restraining criterion, such as the example handover restraining criterion 1190.
  • the example handover restraining criterion 1190 is satisfied when the neighbor signal quality (such as SNR) becomes higher than the signal quality of the SpCell by an offset amount for a time window T.
  • Inequality (5) and inequality (6) may be used to determine when the reporting criterion 1170 is satisfied and inequality (7) may be used to determine when the example handover restraining criterion 1190 is satisfied.
  • the modified Events described in Figure 7 may enable a UE to mitigate excessive handovers by adding a handover restraining criterion before sending a triggered measurement report that would otherwise by triggered by just the reporting criterion.
  • Some other techniques for mitigating excessive handovers may be based on a network-provided cell blacklist or cell whitelist.
  • FIG 12 shows a flowchart illustrating an example process 1200 to mitigate excessive handovers using a network-provided cell blacklist.
  • the network-provided cell blacklist may be provided by a base station that provides the SpCell of either the MCG or SCG.
  • the example operations of process 1200 may be implemented by a base station or its components as described herein.
  • the process 1200 may be performed by an apparatus such as an eNB or gNB described herein or a wireless communication device such as the wireless communication device 1400 described with reference to Figure 14.
  • the apparatus may establish a connection with a user equipment (UE) via a serving cell of the first base station.
  • UE user equipment
  • the apparatus may prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold.
  • the apparatus may transmit a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • the traditional measurement configuration for a traditional Event A3 may include the following parameters: eventA3 SEQUENCE ⁇ a3-Offset MeasTriggerQuantityOffset, reportOnLeave BOOLEAN, hysteresis, timeToTrigger, useWhiteCellList BOOLEAN
  • the a3-Offset parameter is the offset value(s) (such as Off) to be used in NR measurement report triggering condition for event.
  • a typical value for the a3-Offset parameter may be 2 dB.
  • the reportOnLeave parameter indicates whether the event is triggered when the reporting criteria was satisfied and when the reporting criteria is no longer satisfied. The examples of this disclosure are based on entering an event, so the reportOnLeave may be set to false.
  • the hysteresis parameter indicates the Hys variable for inequality (1).
  • the timeToTrigger parameter indicates the duration of the timeToTrigger. The reporting criterion may be satisfied if the inequality (1) is true for a duration of the timeToTrigger.
  • a typical value for the timeToTrigger parameter may be 320 milliseconds.
  • the useWhiteCellList parameter indicates whether only the cells included in the white-list of the associated neighbor cell are to be measured for the event. A typical value for this parameter is false.
  • the measurement configuration does not currently include a parameter to indicate a cell blacklist.
  • the measurement configuration may be modified to include a cell blacklist that applies to the Event A3.
  • the measurement configuration for Event A4 or Event A5 may be modified to include a cell blacklist.
  • the apparatus may determine which cells to include in the cell blacklist based on the history of handover events between particular cells that share partially overlapping coverage. In some implementations, the apparatus may use machine learning or pattern matching to identify cells which create undesirable excessive handover events. In some implementations, the cell blacklist may be based on an architecture or deployment map associated with the base stations in a geographic area.
  • a UE that receives a measurement configuration that includes the cell blacklist may only send triggered measurement reports for neighbor cells that are not indicted in the cell blacklist.
  • Figure 13 shows a conceptual diagram of an example configuration message 1300.
  • the configuration message 1300 may include a frame header 1324 and a payload 1310.
  • the frame header 1324 may indicate the type of message or other frame control information.
  • the payload 1310 may include a variety of elements or fields 1332.
  • Figure 10 includes several example elements or fields 1360.
  • the example elements or fields 1360 may include a measurement configuration 1362.
  • the measurement configuration 1362 may indicate, among other things, which triggered measurement reports are configured, measurement objects (regarding neighbor cells), and the like.
  • the example elements or fields 1360 may include reporting criteria parameters 1364 for each configured reporting event.
  • the example elements or fields 1360 may include a neighbor cell whitelist 1366, a neighbor cell blacklist 1367, or both.
  • the reporting criteria parameters 1364, the neighbor cell whitelist 1366, and the neighbor cell blacklist 1367 may be formatted as subfields within the measurement configuration 1362 or may be included as separate fields in the configuration message 1300.
  • example configuration message 1300 may be included in the example configuration message 1300 to configure the UE with a measurement configuration such as those described herein.
  • the example message 1300 may be part of an RRC Connection Reconfiguration message.
  • FIG 14 shows a block diagram of an example wireless communication device 1400.
  • the wireless communication device 1400 can be an example of a device for use in a UE, such as UE 120 described above with reference to Figure 1.
  • the wireless communication device 1400 is capable of transmitting (or outputting for transmission) and receiving wireless communications.
  • the wireless communication device 1400 can be, or can include, a chip, system on chip (SoC), chipset, package or device.
  • SoC system-on-chip
  • the term “system-on-chip” (SoC) is used herein to refer to a set of interconnected electronic circuits typically, but not exclusively, including one or more processors, a memory, and a communication interface.
  • the SoC may include a variety of different types of processors and processor cores, such as a general purpose processor, a central processing unit (CPU), a digital signal processor (DSP), a graphics processing unit (GPU), an accelerated processing unit (APU), a sub-system processor, an auxiliary processor, a single-core processor, and a multicore processor.
  • CPU central processing unit
  • DSP digital signal processor
  • GPU graphics processing unit
  • APU accelerated processing unit
  • the SoC may further include other hardware and hardware combinations, such as a field programmable gate array (FPGA), a configuration and status register (CSR), an application-specific integrated circuit (ASIC), other programmable logic device, discrete gate logic, transistor logic, registers, performance monitoring hardware, watchdog hardware, counters, and time references.
  • SoCs may be integrated circuits (ICs) configured such that the components of the IC reside on the same substrate, such as a single piece of semiconductor material (such as, for example, silicon).
  • SIP system in a package
  • a SIP may include a single substrate on which multiple IC chips or semiconductor dies are stacked in a vertical configuration.
  • MCMs multi-chip modules
  • a SIP also may include multiple independent SoCs coupled together via high speed communication circuitry and packaged in close proximity, such as on a single motherboard or in a single mobile communication device. The proximity of the SoCs facilitates high speed communications and the sharing of memory and resources.
  • multicore processor is used herein to refer to a single IC chip or chip package that contains two or more independent processing cores (for example a CPU core, IP core, GPU core, among other examples) configured to read and execute program instructions.
  • An SoC may include multiple multicore processors, and each processor in an SoC may be referred to as a core.
  • multiprocessor may be used herein to refer to a system or device that includes two or more processing units configured to read and execute program instructions.
  • the wireless communication device 1400 may include one or more modems 1402.
  • the one or more modems 1402 may include a WWAN modem (for example, a 3GPP 4G LTE or 5G compliant modem).
  • the wireless communication device 1400 also includes one or more radios 1404 (collectively “the radio 1404”).
  • the wireless communication device 1400 further includes one or more processors, processing blocks or processing elements 1406 (collectively “the processor 1406”) and one or more memory blocks or elements 1407 (collectively “the memory 1407”).
  • the modem 1402 can include an intelligent hardware block or device such as, for example, an application-specific integrated circuit (ASIC) among other possibilities.
  • the modem 1402 is generally configured to implement a PHY layer.
  • the modem 1402 is configured to modulate packets and to output the modulated packets to the radio 1404 for transmission over the wireless medium.
  • the modem 1402 is similarly configured to obtain modulated packets received by the radio 1404 and to demodulate the packets to provide demodulated packets.
  • the modem 1402 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), a coder, a decoder, a multiplexer and a demultiplexer.
  • DSP digital signal processing
  • AGC automatic gain control
  • data obtained from the processor 1406 is provided to a coder, which encodes the data to provide encoded bits.
  • the encoded bits are mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols.
  • the modulated symbols may be mapped to a number NSS of spatial streams or a number NSTS of space-time streams.
  • the modulated symbols in the respective spatial or space-time streams may be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and subsequently provided to the DSP circuitry for Tx windowing and filtering.
  • IFFT inverse fast Fourier transform
  • the digital signals may be provided to a digital-to-analog converter (DAC).
  • DAC digital-to-analog converter
  • the resultant analog signals may be provided to a frequency upconverter, and ultimately, the radio 1404.
  • the modulated symbols in the respective spatial streams are precoded via a steering matrix prior to their provision to the IFFT block.
  • digital signals received from the radio 1404 are provided to the DSP circuitry, which is configured to acquire a received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offsets.
  • the DSP circuitry is further configured to digitally condition the digital signals, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting for I/Q imbalance), and applying digital gain to ultimately obtain a narrowband signal.
  • the output of the DSP circuitry may be fed to the AGC, which is configured to use information extracted from the digital signals, for example, in one or more received training fields, to determine an appropriate gain.
  • the output of the DSP circuitry also is coupled with the demodulator, which is configured to extract modulated symbols from the signal and, for example, compute the logarithm likelihood ratios (LLRs) for each bit position of each subcarrier in each spatial stream.
  • the demodulator is coupled with the decoder, which may be configured to process the LLRs to provide decoded bits.
  • the decoded bits from all of the spatial streams are fed to the demultiplexer for demultiplexing.
  • the demultiplexed bits may be descrambled and provided to the MAC layer (the processor 1406) for processing, evaluation, or interpretation.
  • the radio 1404 generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) and at least one RF receiver (or “receiver chain”), which may be combined into one or more transceivers.
  • the RF transmitters and receivers may include various DSP circuitry including at least one power amplifier (PA) and at least one low-noise amplifier (LNA), respectively.
  • PA power amplifier
  • LNA low-noise amplifier
  • the RF transmitters and receivers may, in turn, be coupled to one or more antennas.
  • the wireless communication device 1400 can include, or be coupled with, multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain).
  • the symbols output from the modem 1402 are provided to the radio 1404, which transmits the symbols via the coupled antennas.
  • symbols received via the antennas are obtained by the radio 1404, which provides the symbols to the modem 1402.
  • the processor 1406 can include an intelligent hardware block or device such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD) such as a field programmable gate array (FPGA), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.
  • the processor 1406 processes information received through the radio 1404 and the modem 1402, and processes information to be output through the modem 1402 and the radio 1404 for transmission through the wireless medium.
  • the processor 1406 may generally control the modem 1402 to cause the modem to perform various operations described above.
  • the memory 1407 can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof.
  • the memory 1407 also can store non-transitory processor- or computer-executable software (SW) code containing instructions that, when executed by the processor 1406, cause the processor to perform various operations described herein for wireless communication, including the generation, transmission, reception and interpretation of MPDUs, frames or packets.
  • SW computer-executable software
  • various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein can be implemented as one or more modules of one or more computer programs.
  • Figures 1-14 and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently.
  • a method for wireless communication performed by an apparatus of a user equipment including: establishing at least a first connection with a serving cell of a base station (BS); receiving a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell, where the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; monitoring for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters; and communicating the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • a measurement configuration that includes a reporting criterion for a measurement reporting event, the
  • Clause 2 The method of clause 1, further including: obtaining signal measurements of a plurality of reference signals from the BS and one or more neighbor cells; determining that the reporting criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the one or more network-provided parameters; determining that the handover restraining criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the UE-configured parameter; and detecting the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • Clause 3 The method of any one of clauses 1-2, further including refraining from communicating the triggered measurement report when the handover restraining criterion is not satisfied regardless of whether the reporting criterion is satisfied.
  • Clause 4 The method of any one of clauses 1-3, where the one or more network- provided parameters includes a first signal measurement offset to adjust a measurement result of the serving cell before evaluating the reporting criterion, and where the UE-configured parameter includes a second signal measurement offset that is greater than the first signal measurement offset such that the measurement result of the serving cell is adjusted to a greater value before evaluating the handover restraining criterion.
  • Clause 5 The method of clause 4, further including: determining the second signal measurement offset based on the first signal measurement offset and an adjustment value, where the adjustment value is based on a quantity of handover events during a preceding time period, a time since a previous handover event, a movement speed of the UE, or any combination thereof.
  • Clause 6 The method of any one of clauses 1-5, further including: determining a quantity of handover events during a preceding time period; determining a frequency of handovers based on the quantity of handover events during the preceding time period; and adjusting the UE-configured parameter of the handover restraining criterion based on the frequency of handovers.
  • Clause 7 The method of any one of clauses 1-6, where the handover restraining criterion cannot be satisfied until expiration of a delay timer initiated after a previous handover event, the method further including: setting a duration of the delay timer based on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiating the delay timer after the previous handover event.
  • setting the duration of the delay timer includes: determining a frequency of handovers based on the quantity of handover events during the preceding time period; setting the duration to a first value when the frequency of handovers is below a handover frequency threshold; and setting the duration to a second value when the frequency of handovers is above the handover frequency threshold, the second value higher than the first value.
  • setting the duration of the delay timer includes: setting the duration to a first value when the UE stationary; setting the duration to a second value when the UE is non-stationary and the movement speed of the UE is lower than a speed threshold, the second value lower than the first value; and setting the duration to a third value when the UE is non-stationary and the movement speed of the UE is higher than the speed threshold, the third value lower than the second value.
  • Clause 10 The method of any one of clauses 7-9, further including: determining whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disabling the delay timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
  • Clause 11 The method of any one of clauses 1-10, where the UE-configured parameter limits the occurrence of the measurement reporting event such that the UE is prevented from ping-pong handovers between the serving cell and the neighbor cell.
  • Clause 12 The method of any one of clauses 1-11, further including: enabling the handover restraining criterion when the handover restraining criterion is disabled and a signal measurement of the serving cell is greater than a first signal strength threshold (RSRP High Threshold); and disabling the handover restraining criterion when the handover restraining criterion is enabled and the signal measurement of the serving cell is less than a second signal strength threshold (RSRP Low Threshold).
  • RSRP High Threshold a first signal strength threshold
  • RSRP Low Threshold a second signal strength threshold
  • Clause 15 The method of any one of clauses 1-14, where the measurement reporting event is an A3 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a corresponding signal measurement of the serving cell plus a network-provided offset, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
  • Clause 16 The method of any one of clauses 1-15, where the measurement reporting event is an A4 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a network-provided threshold, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
  • Clause 17 The method of any one of clauses 1-16, where the measurement reporting event is an A5 event specified in a technical standard and the reporting criterion includes a current signal measurement of the first connection being below a first signal strength threshold and the signal measurement of the neighbor cell being greater than a second signal strength threshold, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
  • the measurement reporting event is an A5 event specified in a technical standard and the reporting criterion includes a current signal measurement of the first connection being below a first signal strength threshold and the signal measurement of the neighbor cell being greater than a second signal strength threshold
  • the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
  • the handover restraining criterion includes one or more criterion selected from a group consisting of: an expiration of a delay timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
  • establishing at least the first connection includes: establishing the first connection with the serving cell of the BS in a Long-Term Evolution (LTE) radio access network (RAN), the serving cell being designated as a primary serving cell; and establishing a second connection with a secondary serving cell of another BS in a 5G New Radio (NR) RAN.
  • LTE Long-Term Evolution
  • NR 5G New Radio
  • a method for wireless communication performed by a first base station including: establishing a connection with a user equipment (UE) via a serving cell of the first base station; preparing a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and transmitting a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • UE user equipment
  • Clause 22 The method of clause 21, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
  • Clause 23 The method of any one of clauses 21-22, where preparing the cell blacklist includes: determining a frequency of handover events associated with the neighbor cell based on the quantity of handover events over a time period; and including the neighbor cell in the cell blacklist if the frequency of handover events is above a threshold.
  • Clause 24 The method of any one of clauses 21-23, where preparing the cell blacklist includes: determining that the neighbor cell provides an overlapping geographic coverage area with the serving cell; determining that the UE is in a location of the overlapping geographic coverage area and that the quantity of handover events for the UE is higher than an average quantity of handover events for other UEs in other locations of the overlapping geographic coverage area; and including the neighbor cell in the cell blacklist for the UE.
  • a user equipment including: at least one modem configured to: establish at least a first connection with a serving cell of a base station (BS), and obtain a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell, where the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; a processing system configured to monitor for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters; and the at least one modem configured to communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
  • BS base station
  • Clause 26 The UE of clause 25, where the processing system is further configured to: determine a quantity of handover events during a preceding time period; determine a frequency of handovers based on the quantity of handover events during the preceding time period; and adjust the UE-configured parameter of the handover restraining criterion based on the frequency of handovers.
  • Clause 27 The UE of any one of clauses 25-26, where the processing system is further configured to: set a duration of a delay timer based on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiate the delay timer after a previous handover event, where the handover restraining criterion cannot be satisfied until expiration of the delay timer initiated after the previous handover event.
  • the UE of any one of clauses 25-27 further including: at least one transceiver coupled to the at least one modem; at least one antenna coupled to the at least one transceiver to wirelessly transmit signals output from the at least one transceiver and to wirelessly receive signals for input into the at least one transceiver; and a housing that encompasses at least the processing system, the at least one modem, the at least one transceiver, and at least a portion of the at least one antenna.
  • An apparatus of a first base station including: a processing system configured to: establish a connection with a user equipment (UE) via a serving cell of the first base station, and prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and at least one modem configured to output a measurement configuration for transmission to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • UE user equipment
  • Clause 30 The apparatus of clause 29, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
  • a method for wireless communication performed by an apparatus of a user equipment (UE), including: establishing a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; receiving a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and sending the triggered measurement report when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
  • LTE Long-Term Evolution
  • NR 5GNew Radio
  • Clause 32 The method of clause 31, further including: refraining from sending the triggered measurement report when the handover moderation criterion is not satisfied.
  • the handover moderation criterion includes one or more criterion selected from a group consisting of: an expiration of a hold timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
  • Clause 34 The method of clause 33, further including: determining a duration of the hold timer, the signal strength change threshold or the signal quality precondition threshold based on a user-configurable setting, a network-configurable setting or a manufacturer configurable setting.
  • Clause 35 The method of any one of clauses 31-34, further including: determining a quantity of handover events during a preceding time period; determining a frequency of handovers based on the quantity of handover events during the preceding time period; and adjusting the handover moderation criterion based on the frequency of handovers.
  • setting the duration of the hold timer includes: setting the duration to a first value when the frequency of handovers is above a first level; and setting the duration to a second value when the frequency of handovers is below the first level, the first value higher than the second value.
  • Clause 40 The method of clause 36, further including: determining that the UE is stationary; and evaluating the handover moderation criterion as a precondition to sending the triggered measurement report based on a determination that the UE is stationary.
  • Clause 42 The method of any one of clauses 31-41, where the measurement report is an A4 event report and the reporting criterion includes the measurement being greater than a signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
  • Clause 43 The method of any one of clauses 31-42, where the measurement report is an A5 event report and the reporting criterion includes a current signal strength of the first connection being below a first signal strength threshold and the measurement of the neighbor cell being greater than a second signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
  • a method for wireless communication performed by an apparatus of a first base station, including: establishing a connection with a user equipment (UE) via a first serving cell of the first base station; determining a quantity of handover events where the UE’s connection with the first serving cell is handed over to a neighbor cell of the first base station or a second base station; preparing a cell blacklist that includes the neighbor cell based on a determination that the quantity of handover events is above a threshold; and transmitting the measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
  • UE user equipment
  • Clause 46 The method of clause 45, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the measurement report for the one or more cells included in the cell blacklist.
  • Clause 47 The method of any one of clauses 45-46, where preparing the cell blacklist includes: determining a frequency of handover events associated with the neighbor cell based on the quantity of handover events over a time period; and including the neighbor cell in the cell blacklist if the frequency of handover events is above a threshold.
  • Clause 48 The method of any one of clauses 45-47, where preparing the cell blacklist includes: determining that the neighbor cell provides an overlapping geographic coverage area with the first serving cell or the second serving cell; determining that the UE is in a location of the overlapping geographic coverage area and that the quantity of handover events for the UE is higher than an average quantity of handover events for other UEs in other locations of the overlapping geographic coverage area; and including the neighbor cell in the cell blacklist for the UE.
  • a user equipment (UE) for wireless communication including: one or more processors configured to: establish a first connection with a first serving cell of a Long- Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; an interface configured to: obtain a measurement configuration including a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
  • LTE Long- Term Evolution
  • NR 5G New Radio
  • Clause 50 The UE of clause 49, further including: the one or more processors configured to cause the interface to refrain from outputting the triggered measurement report when the handover moderation criterion is not satisfied.
  • the handover moderation criterion includes one or more criterion selected from a group consisting of: an expiration of a hold timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
  • Clause 52 The UE of clause 51, further including: the one or more processors configured to determine a duration of the hold timer, the signal strength change threshold or the signal quality precondition threshold based on a user-configurable setting, a network- configurable setting or a manufacturer configurable setting.
  • Clause 53 The UE of any one of clauses 49-52, where the one or more processors are further configured to: determine a quantity of handover events during a preceding time period; determine a frequency of handovers based on the quantity of handover events during the preceding time period; and adjust the handover moderation criterion based on the frequency of handovers.
  • Clause 55 The UE of clause 54, where the one or more processors are further configured to: set the duration to a first value when the frequency of handovers is above a first level; and set the duration to a second value when the frequency of handovers is below the first level, the first value higher than the second value.
  • Clause 56 The UE of clause 54, where the one or more processors are further configured to: determine that the handover frequency is within a first range from among a plurality of ranges, where each range of the plurality of ranges is associated with a different duration value; and set the duration of the hold timer based on a duration value of the first range.
  • Clause 57 The UE of clause 54, where the one or more processors are further configured to: determine whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disable the hold timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
  • Clause 58 The UE of clause 54, where the one or more processors are further configured to determine whether the UE is stationary or nonstationary, and evaluate the handover moderation criterion as a precondition to sending the triggered measurement report based on a determination that the UE is stationary.
  • Clause 59 The UE of any one of clauses 49-58, where the measurement report is an A3 event report and the reporting criterion includes the measurement being greater than a corresponding measurement of the first serving cell or the second serving cell, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
  • Clause 60 The UE of any one of clauses 49-59, where the measurement report is an A4 event report and the reporting criterion includes the measurement being greater than a signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
  • Clause 62 The UE of any one of clauses 49-61, where the measurement configuration includes a cell blacklist associated with the triggered measurement report, and where the one or more processor is further configured to: determine whether the neighbor cell is in the cell blacklist; cause the interface to output the triggered measurement report when both the reporting criterion and the handover moderation criterion are satisfied and the neighbor cell is not included in the cell blacklist.
  • a wireless communication device including: at least one modem; at least one processor communicatively coupled with the at least one modem; and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
  • LTE Long-Term Evolution
  • NR 5GNew Radio
  • a portable electronic device including: a wireless communication device including: at least one modem; at least one processor communicatively coupled with the at least one modem; and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report; a plurality of antennas coupled to: establish at least a first
  • a machine-readable medium having processor-readable instructions stored therein that, when executed by at least one processor of a user equipment (UE), cause the UE: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
  • LTE Long-Term Evolution
  • NR 5GNew Radio
  • a system for use in a user equipment including: means for establishing a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; means for receiving a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and means for sending the triggered measurement report when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
  • LTE Long-Term Evolution
  • NR 5G New Radio
  • a method of wireless communication performed by a user equipment including: obtaining signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; detecting an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and communicating, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
  • Clause 68 The method of clause 67, further including: receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the receiving the measurement configuration includes receiving the measurement configuration in one or more BCCHs of the plurality of BCCHs.
  • BCCHs broadcast control channels
  • Clause 69 The method of any one of clauses 67-68, further including: receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the receiving the measurement configuration includes receiving the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 70 The method of any one of clauses 67-69, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the communicating the measurement report includes transmitting, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
  • PUCCHs physical uplink control channels
  • Clause 71 The method of any one of clauses 67-70, further including: receiving a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the receiving the measurement configuration includes receiving the measurement configuration in a radio resource control (RRC) message.
  • RRC radio resource control
  • Clause 72 The method of clause 71, further including: modifying the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 73 The method of clause 71, where the obtaining the signal measurements includes: obtaining a plurality of predetermined parameters from the measurement configuration; determining whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generating the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
  • Clause 74 The method of clause 73, where the generating the second signal measurement offset includes: determining whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generating the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
  • Clause 75 The method of clause 74, further including: retaining the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
  • Clause 76 The method of clause 74, further including: initiating an event evaluation operation to detect an occurrence of the specified measurement event; determining whether the first signal measurement offset is overridden by the second signal measurement offset; determining whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and determining whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 77 The method of clause 76, where the detecting the occurrence of the specified measurement event includes: applying the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • the detecting the occurrence of the specified measurement event includes: applying the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
  • Clause 79 The method of clause 76, where the initiating the event evaluation operation includes: monitoring the signal measurement of the BS over time; comparing the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and comparing the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 80 The method of any one of clauses 67-79, further including: measuring a plurality of transmission beams associated with the BS during a first time period; and obtaining a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
  • RSRP reference signal received power
  • Clause 81 The method of clause 80, further including: receiving, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
  • Clause 82 The method of clause 81, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the receiving the request includes receiving the request in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 83 The method of clause 81, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 84 The method of clause 81, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 85 The method of any one of clauses 67-84, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
  • RSRP reference signal received power
  • Clause 86 The method of clause 85, where the downlink specific reference signal includes a synchronization signal block (SSB).
  • SSB synchronization signal block
  • Clause 87 The method of clause 85, where the downlink specific reference signal includes a channel state information reference signal (CSI-RS).
  • CSI-RS channel state information reference signal
  • Clause 88 The method of clause 88, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
  • RSSI received signal strength indicator
  • Clause 89 The method of clause 88, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
  • RSRQ reference signal received quality
  • Clause 90 The method of any one of clauses 67-89, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
  • Clause 91 The method of clause 90, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
  • a user equipment including: a processor configured to: obtain signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; detect an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and a transceiver configured to: communicate, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
  • a processor configured to: obtain signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; detect an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and
  • Clause 93 The UE of clause 92, where the transceiver is further configured to: receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
  • BCCHs broadcast control channels
  • Clause 94 The UE of any one of clauses 92-93, where the transceiver is further configured to: receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 95 The UE of any one of clauses 92-94, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to communicate the measurement report is further configured to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
  • PUCCHs physical uplink control channels
  • Clause 96 The UE of any one of clauses 92-95, where the transceiver is further configured to: receive a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in a radio resource control (RRC) message.
  • RRC radio resource control
  • Clause 97 The UE of clause 96, where the processor is further configured to: modify the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 98 The UE of clause 96, where the processor configured to obtain the signal measurements is further configured to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
  • the processor configured to generate the second signal measurement offset is further configured to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
  • Clause 100 The UE of clause 99, where the processor is further configured to: retain the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
  • Clause 101 The UE of clause 99, where the processor is further configured to: initiate an event evaluation operation to detect an occurrence of the specified measurement event; determine whether the first signal measurement offset is overridden by the second signal measurement offset; determine whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and determine whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 102 The UE of clause 101, where the processor configured to detect the occurrence of the specified measurement event is further configured to: apply the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • Clause 103 The UE of clause 101, where the processor configured to detect the occurrence of the specified measurement event is further configured to: apply the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
  • Clause 104 The UE of clause 101, where the processor configured to initiate the event evaluation operation is further configured to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 105 The UE of any one of clauses 92-104, where the processor is further configured to: measure a plurality of transmission beams associated with the BS during a first time period; and obtain a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
  • RSRP reference signal received power
  • Clause 106 The UE of clause 105, where the transceiver is further configured to: receive, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
  • the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period
  • the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period
  • the transceiver configured to receive the request is further configured to receive the request in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 108 The UE of clause 106, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 109 The UE of clause 106, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 110 The UE of any one of clauses 92-109, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
  • RSRP reference signal received power
  • Clause 111 The UE of clause 110, where the downlink specific reference signal includes a synchronization signal block (SSB).
  • SSB synchronization signal block
  • Clause 114 The UE of clause 113, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
  • RSRQ reference signal received quality
  • Clause 115 The UE of any one of clauses 92-114, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
  • UE user equipment
  • BS base station
  • one or more neighbor cells code for causing the UE to detect an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first
  • Clause 118 The non-transitory computer-readable medium of clause 117, further including: code for causing the UE to receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
  • BCCHs broadcast control channels
  • Clause 119 The non-transitory computer-readable medium of any one of clauses 117-118, further including: code for causing the UE to receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 120 The non-transitory computer-readable medium of any one of clauses 117-119, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to communicate the measurement report is further configured to cause the UE to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
  • PUCCHs physical uplink control channels
  • Clause 121 The non-transitory computer-readable medium of any one of clauses 117-120, further including: code for causing the UE to receive a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in a radio resource control (RRC) message.
  • RRC radio resource control
  • Clause 122 The non-transitory computer-readable medium of clause 121, further including: code for causing the UE to modify the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 123 The non-transitory computer-readable medium of clause 121, where the code for causing the UE to obtain the signal measurements is further configured to cause the UE to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
  • Clause 124 Clause 124.
  • non-transitory computer-readable medium of clause 123 where the code for causing the UE to generate the second signal measurement offset is further configured to cause the UE to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
  • Clause 125 The non-transitory computer-readable medium of clause 124, further including: code for causing the UE to retain the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
  • Clause 126 The non-transitory computer-readable medium of clause 124, further including: code for causing the UE to initiate an event evaluation operation to detect an occurrence of the specified measurement event; code for causing the UE to determine whether the first signal measurement offset is overridden by the second signal measurement offset; code for causing the UE to determine whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and code for causing the UE to determine whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 127 The non-transitory computer-readable medium of clause 126, where the code for causing the UE to detect the occurrence of the specified measurement event is further configured to cause the UE to: applying the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • Clause 128 Clause 128.
  • non-transitory computer-readable medium of clause 126 where the code for causing the UE to initiate the event evaluation operation is further configured to cause the UE to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 130 The non-transitory computer-readable medium of any one of clauses 117-129, further including: code for causing the UE to measure a plurality of transmission beams associated with the BS during a first time period; and code for causing the UE to obtain a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
  • RSRP reference signal received power
  • Clause 131 The non-transitory computer-readable medium of clause 130, further including: code for causing the UE to receive, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
  • Clause 132 The non-transitory computer-readable medium of clause 131, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the code for causing the UE to receive the request is further configured to cause the UE to receive the request in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 133 The non-transitory computer-readable medium of clause 131, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 134 The non-transitory computer-readable medium of clause 131, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 135. The non-transitory computer-readable medium of any one of clauses 117-134, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
  • RSRP reference signal received power
  • Clause 136 The non-transitory computer-readable medium of clause 135, where the downlink specific reference signal includes a synchronization signal block (SSB).
  • SSB synchronization signal block
  • Clause 137 The non-transitory computer-readable medium of clause 135, where the downlink specific reference signal includes a channel state information reference signal (CSI- RS).
  • CSI- RS channel state information reference signal
  • Clause 138 The non-transitory computer-readable medium of clause 135, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
  • RSSI received signal strength indicator
  • Clause 139 The non-transitory computer-readable medium of clause 138, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
  • RSRQ reference signal received quality
  • Clause 140 The non-transitory computer-readable medium of any one of clauses 117-139, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
  • Clause 141 The non-transitory computer-readable medium of clause 140, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
  • a user equipment including: means for obtaining signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; means for detecting an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and means for communicating, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
  • Clause 143 The UE of clause 142, further including: means for receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the means for receiving the measurement configuration is further configured to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
  • BCCHs broadcast control channels
  • Clause 144 The UE of any one of clauses 142-143, further including: means for receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the means for receiving the measurement configuration is further configured to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period
  • the means for communicating the measurement report is further configured to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
  • PUCCHs physical uplink control channels
  • Clause 146 The UE of any one of clauses 142-145, further including: means for receiving a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the means for receiving the measurement configuration is further configured to receive the measurement configuration in a radio resource control (RRC) message.
  • RRC radio resource control
  • Clause 147 The UE of clause 146, further including: means for modifying the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 148 The UE of clause 146, where the means for obtaining the signal measurements is further configured to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
  • Clause 149 The UE of clause 148, where the means for obtaining the signal measurements is further configured to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
  • Clause 150 The UE of clause 149, further including: means for retaining the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
  • Clause 151 The UE of clause 149, further including: means for initiating an event evaluation operation to detect an occurrence of the specified measurement event; means for determining whether the first signal measurement offset is overridden by the second signal measurement offset; means for determining whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and means for determining whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 152 The UE of clause 151, where the means for detecting the occurrence of the specified measurement event is further configured to: apply the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
  • Clause 153 Clause 153.
  • the means for detecting the occurrence of the specified measurement event is further configured to: apply the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
  • Clause 154 The UE of clause 151, where the means for initiating the event evaluation operation is further configured to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
  • Clause 155 The UE of any one of clauses 142-154, further including: means for measuring a plurality of transmission beams associated with the BS during a first time period; and means for obtaining a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
  • RSRP reference signal received power
  • Clause 156 The UE of clause 155, further including: means for receiving, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
  • Clause 157 The UE of clause 156, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the means for receiving the request is further configured to receive the request in one or more PDCCHs of the plurality of PDCCHs.
  • PDCCHs physical downlink control channels
  • Clause 158 The UE of clause 156, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 159 The UE of clause 156, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
  • Clause 160 The UE of any one of clauses 142-159, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
  • RSRP reference signal received power
  • Clause 161 The UE of clause 160, where the downlink specific reference signal includes a synchronization signal block (SSB).
  • SSB synchronization signal block
  • Clause 163 The UE of clause 160, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
  • RSSI received signal strength indicator
  • Clause 164 The UE of clause 163, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
  • RSRQ reference signal received quality
  • Clause 165 The UE of any one of clauses 142-164, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
  • Clause 166 The UE of clause 165, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
  • the term “component” is intended to be broadly construed as hardware, firmware, or a combination of hardware and software.
  • a processor is implemented in hardware, firmware, or a combination of hardware and software.
  • the phrase “based on” is intended to be broadly construed to mean “based at least in part on.”
  • satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like.
  • a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members.
  • “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.
  • the hardware and data processing apparatus used to implement the various illustrative components, logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.
  • a general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine.
  • a processor also may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
  • particular processes, operations and methods may be performed by circuitry that is specific to a given function.
  • implementations of the subject matter described in this specification can be implemented as software.
  • various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein can be implemented as one or more modules of one or more computer programs.
  • Such computer programs can include non-transitory processor- or computer- executable instructions encoded on one or more tangible processor- or computer-readable storage media for execution by, or to control the operation of, data processing apparatus including the components of the devices described herein.
  • storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store program code in the form of instructions or data structures. Combinations of the above should also be included within the scope of storage media.
  • the terms “user equipment”, “wireless communication device”, “mobile communication device”, “communication device”, or “mobile device” refer to any one or all of cellular telephones, smartphones, portable computing devices, personal or mobile multi- media players, laptop computers, tablet computers, smartbooks, Intemet-of-Things (IoT) devices, palm-top computers, wireless electronic mail receivers, multimedia Internet enabled cellular telephones, wireless gaming controllers, display sub-systems, driver assistance systems, vehicle controllers, vehicle system controllers, vehicle communication system, infotainment systems, vehicle telematics systems or subsystems, vehicle display systems or subsystems, vehicle data controllers or routers, and similar electronic devices which include a programmable processor and memory and circuitry configured to perform operations as described herein.
  • IoT Intemet-of-Things
  • SIM Subscriber identification module
  • SIM Subscriber Identity
  • SIM card Subscriber identification module
  • subscriber identification module refers to a memory that may be an integrated circuit or embedded into a removable card, and that stores an International Mobile Subscriber Identity (IMSI), related key, or other information used to identify or authenticate a mobile communication device on a network and enable a communication service with the network.
  • IMSI International Mobile Subscriber Identity
  • subscription is used herein as a shorthand reference to refer to the communication service associated with and enabled by the information stored in a particular SIM as the SIM and the communication network, as well as the services and subscriptions supported by that network, correlate to one another.
  • a SIM used in various examples may contain user account information, an international mobile subscriber identity (IMSI), a set of SIM application toolkit (SAT) commands, and storage space for phone book contacts.
  • IMSI international mobile subscriber identity
  • SAT SIM application toolkit
  • a SIM card may further store home identifiers (such as, a System Identification Number (SID)/Network Identification Number (NID) pair, a Home Public Land Mobile Number (HPLMN) code, among other examples) to indicate the SIM card network operator provider.
  • An Integrated Circuit Card Identity (ICCID) SIM serial number may be printed on the SIM card for identification.
  • a SIM may be implemented within a portion of memory of the mobile communication device, and thus need not be a separate or removable circuit, chip or card.

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Abstract

This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer-readable media, to mitigate excessive handovers in a wireless communication system. The excessive handovers may be related to a ping-pong situation that impacts service and performance of communication between a user equipment (UE) and a radio access network (RAN) of the wireless communication system. A traditional reporting criterion may trigger a measurement report that causes a base station to perform a handover. In some implementations, the UE may refrain from sending the measurement report based on a handover restraining criterion that operates to further limit the traditional reporting criterion for a triggered measurement report. The handover restraining criterion may be based on a delay timer, a change in location of the UE, a speed of the UE movement, a neighbor signal quality comparison for a time period, or a network-provided cell blacklist, among other examples.

Description

MITIGATION OF EXCESSIVE HANDOVERS IN A WIRELESS COMMUNICATION
SYSTEM
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This Patent Application claims priority to Indian Provisional Patent Application No., 202041025685 filed June 18, 2020, entitled “MITIGATION OF EXCESSIVE HANDOVERS IN A WIRELESS COMMUNICATION SYSTEM”, and claims priority to International Patent Corporation Treaty Patent Application No. PCT/CN2020/096113, filed June 15, 2020 entitled “HANDOVER MECHANISM FOR RESTRAINING PING-PONG HANDOVER IN NEW RADIO CELLS,” and assigned to the assignee hereof. The disclosures of the prior Applications are considered part of and are incorporated by reference in this Patent Application.
TECHNICAL FIELD
[0002] Aspects of the present disclosure generally relate to wireless communication and techniques to mitigate excessive handovers of a user equipment (UE) in a wireless communication system.
DESCRIPTION OF THE RELATED TECHNOLOGY [0003] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on.
These systems may be capable of supporting communication with multiple users by sharing the available system resources (for example, time, frequency, and power). A wireless communication system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE). Different base stations or network access nodes may implement different radio communication protocols including fourth- generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth-generation (5G) systems which may be referred to as New Radio (NR) systems. NR, which also may be referred to as 5G for brevity, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3 GPP).
[0004] A UE may be configured to establish a connection to a serving cell of a base station. The base station may provide a measurement configuration to the UE to cause the UE to perform a signal measurement of neighbor cells of that same base station or another base station. Based on a signal measurement of a neighbor cell and the measurement configuration, the UE may send a measurement report that is triggered when the signal measurements match a reporting criterion for a measurement reporting event. In cases where radio signals of a neighboring base station, which may be referred to as a target base station, will provide an enhanced connection with a UE relative to a currently serving (or source) base station, the UE may be handed over from the source base station to the target base station. Such techniques may be referred to as handover procedures or mobility procedures, and help to provide continuous connectivity to a UE as it moves in a wireless communications system. However, there may be scenarios in which the UE may experience excessive handovers. Excessive handovers can disrupt connectivity and diminish the user experience.
SUMMARY
[0005] The systems, methods, and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein. [0006] One innovative aspect of the subject matter described in this disclosure can be implemented in a method performed by an apparatus of a user equipment (UE). The method may include establishing at least a first connection with a serving cell of a base station (BS). The method may include receiving a measurement configuration that includes a reporting criterion for a measurement reporting event. The reporting criterion may be configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell. The triggered measurement report may be associated with initiating a handover of the UE from the serving cell to the neighbor cell. The method may include monitoring for an occurrence of measurement reporting event using a handover restraining criterion. The handover restraining criterion may be based on a UE-configured parameter different from the one or more network-provided parameters. The method may include communicating the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
[0007] Another innovative aspect of the subject matter described in this disclosure can be implemented in a user equipment (UE). The UE may include at least one modem configured to establish at least a first connection with a serving cell of a BS, and obtain a measurement configuration that includes a reporting criterion for a measurement reporting event. The reporting criterion may be configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell. The triggered measurement report may be associated with initiating a handover of the UE from the serving cell to the neighbor cell. The UE may include a processing system configured to monitor for an occurrence of measurement reporting event using a handover restraining criterion. The handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters. The at least one modem may be configured to communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
[0008] Another innovative aspect of the subject matter described in this disclosure can be implemented in method for wireless communication performed by a first base station. The method may include establishing a connection with a user equipment (UE) via a serving cell of the first base station. The method may include preparing a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold. The method may include transmitting a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0009] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus of a first base station. The apparatus may include a processing system configured to establish a connection with a user equipment (UE) via a serving cell of the first base station, and prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold. The apparatus may include at least one modem configured to output a measurement configuration for transmission to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0010] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS [0011] Figure 1 shows a pictorial diagram conceptually illustrating an example of a wireless communication system.
[0012] Figure 2 shows a block diagram conceptually illustrating an example of a base station (BS) in communication with a user equipment (UE). [0013] Figure 3 shows a block diagram conceptually illustrating an example wireless communication system in which a UE may have dual connectivity.
[0014] Figure 4 shows a pictorial diagram conceptually illustrating an example of a UE experiencing a ping-pong situation with excessive handovers.
[0015] Figure 5 shows a signaling diagram illustrating a handover process.
[0016] Figure 6 shows a flowchart illustrating an example process for triggered measurement reports using a handover restraining criterion.
[0017] Figure 7 shows a flowchart illustrating an example process with example handover restraining criteria.
[0018] Figure 8 shows a flowchart illustrating an example process using a combination of handover restraining criteria.
[0019] Figure 9 shows a diagram illustrating an example of a signal measurement plot over time and corresponding behavior to enable or disable a handover restraining criterion.
[0020] Figure 10A shows a flow diagram of an example process for monitoring for an occurrence of a measurement reporting event.
[0021] Figure 10B shows a flow diagram of an example process of a measurement evaluation.
[0022] Figure 11 shows example measurement reporting events based on combinations of their respective reporting criterion and a handover restraining criterion.
[0023] Figure 12 shows a flowchart illustrating an example process to mitigate excessive handovers using a network-provided cell blacklist.
[0024] Figure 13 shows a conceptual diagram of an example configuration message according to some implementations.
[0025] Figure 14 shows a block diagram of an example wireless communication device. [0026] Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0027] The following description is directed to certain implementations for the purposes of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. Some of the examples in this disclosure are based on wireless and wired local area network (LAN) communication according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standards, the IEEE 802.3 Ethernet standards, and the IEEE 1901 Powerline communication (PLC) standards. However, the described implementations may be implemented in any device, system or network that is capable of transmitting and receiving radio frequency signals according to any of the wireless communication standards, including any of the IEEE 802.11 standards, the Bluetooth® standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband- CDMA (W-CDMA), Evolution Data Optimized (EV-DO), lxEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals that are used to communicate within a wireless, cellular or internet of things (IOT) network, such as a system utilizing 3G, 4G or 5G, or further implementations thereof, technology.
[0028] A wireless communication system (which also may be referred to as a wireless communication network) may include one or more radio access networks (RANs) that provide access for a user equipment (UE) to communicate with other nodes in the wireless communication system. A radio access network (RAN, sometimes also referred to as a radio network, or access network) may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs). Different types of base stations may be referred to as aNodeB, an LTE evolved NodeB (eNB), a next generation NodeB (gNB), an access point (AP), a radio head, a transmit receive point (TRP), among other examples, depending on the wireless communication standard that the base station supports. One or more LTE base stations may make up an LTE radio access network (RAN). The LTE RAN (sometimes also referred to as an LTE network) provides access to the wireless communication system. Similarly, one or more 5G base stations may make up a 5G New Radio (NR) RAN, and may be referred to as a 5G NR network that provides access to the wireless communication system. The LTE network and 5GNR network may be two examples of a radio access network that can be used to communicate to a core network of the wireless communication system.
[0029] A wireless communication session or association between a user equipment (UE) and a base station (BS) may be referred to as a radio connection (or just a “connection”). A standalone access (SA) mode may refer to a connection in which the initial acquisition and connection are made between the UE and the RAN. A non-standalone access (NS A) mode may refer to the use of multiple connections that include a primary connection to a first base station and a secondary connection to a second base station. For brevity, the examples in this disclosure refer to NSA connections that use dual connectivity (DC). For example, a UE may be configured to establish a first connection to an eNB of an LTE RAN and a second connection to a gNB of a 5G NR RAN. A radio resource control (RRC) configuration for the first connection and second connection may include information about the serving cells of the eNB and the gNB for the UE to use. When it becomes necessary to change the RRC configuration, a base station may send an RRC Connection Reconfiguration message. Reasons to change the RRC configuration may include a handover or change to a neighbor cell (such as another cell of the same base station or another cell of a different base station).
[0030] Although the base station manages the selection and handover procedure, the base station may provide a measurement configuration to the UE to aid in the detection and selection of appropriate neighbor cells. The measurement configuration may include different reporting criteria corresponding to different measurement reporting events. An occurrence of a measurement reporting event occurs when a reporting criterion for that measurement reporting event is satisfied. The occurrence of the measurement reporting event may trigger the UE to transmit a measurement report (also referred to as triggered measurement report). Thus, the UE may be configured to send a particular measurement report when a respective reporting criterion is satisfied. Some of the measurement reports and their respective reporting criteria are designed to initiate a handover based on a signal measurement of a neighboring cell in comparison to a measurement of the current serving cell, a measurement threshold, or both. The signal measurement may be based on a signal strength, such as received signal strength indicator (RSSI), a received signal received power (RSRP). Alternatively, the signal measurement may be based on a signal-to-interference-plus noise ratio (SINR) or a reference signal received quality (RSRQ). However, when the UE measures a similar signal measurement from multiple cells, the reporting criterion may be repetitively satisfied prompting repetitive handovers. For example, after a first handover, the UE may send a subsequent measurement report that initiates another handover back to the previous cell or to another neighbor cell. The cycle may be referred to as a “ping-pong” situation, event or occurrence when repetitive handovers occur between two or more cells.
[0031] This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer-readable media, to prevent a UE from experiencing excessive handovers. Absent the techniques in this disclosure, a UE may trigger multiple handover events when the UE is in overlapping coverage areas of multiple neighboring cells. In some aspects, the UE may use a handover restraining criterion (in addition to the reporting criterion or as a modification to the reporting criterion) to suppress the sending of a trigger measurement report that would otherwise cause a handover. For example, the handover restraining criterion may include an expiration of a delay timer, a signal quality comparison, a signal quality precondition, a cell blacklist, a signal strength change threshold, or any combination thereof. In some implementations, the handover restraining criterion may be adjusted based on a frequency of handovers in a preceding time period or at a particular location. In some implementations, the handover restraining criterion may be modified based on movement speed of the UE or a change in location of the UE. In some implementations, a change in location of the UE may be determined based on a variation in the signal strength of a serving cell over a time period. The handover restraining criterion may be used in conjunction with the reporting criteria for some triggered measurement reports to reduce the occurrence of handover when the UE measures a similar signal strength from multiple cells.
[0032] This disclosure provides several example handover restraining criteria that may be used to mitigate excessive handovers. Examples of handover restraining criterion include an expiration of a delay timer that is initiated after a previous handover, a determination that a current signal strength of the serving cell has changed more than a signal strength change threshold, a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period, a determination that the neighbor signal quality is above a signal quality precondition threshold for a time period, and a determination that the neighbor cell is not included in a cell blacklist provided by the base station. While some portions of this disclosure include some example handover restraining criteria that are used in particular combinations, the example handover restraining criteria may be used in different combinations.
[0033] As stated previously, one example handover restraining criterion may include an expiration of a delay timer that is initiated after a previous handover. The duration of the delay timer may be based on a frequency of handovers. The frequency of handovers may be determined based on a count of handovers over a recent time period. In some implementations, the UE may determine whether the frequency of handovers is in a normal frequency category, a medium frequency category or a high frequency category using different thresholds. The normal frequency category, the medium frequency category and the high frequency category may be related to a quantity of handovers over a time period or may be based on an average quantity of handovers per second. In some implementations, when the frequency of handovers is in the high frequency category, the duration of delay timer may be longer than when the frequency of handovers is in the medium frequency category or normal frequency category. Similarly, when the frequency of handovers is in the medium frequency category, the duration of delay timer may be longer than when the frequency of handovers is in the normal frequency category. In some implementations, when the frequency of handovers is in the normal frequency category, the duration of delay timer may be zero or a minimal value (such as approximately 320 milliseconds or a time indicated by a timeToTrigger parameter of the measurement configuration). [0034] In some implementations, the handover restraining criterion may be adjusted or become conditional based on UE movement. For example, the UE may determine UE movement based on a change in a current signal strength of the current serving cell. UE movement refers to a change in geographic location of the UE relative to one or more base stations. If the current signal strength has changed more than a signal strength change threshold, the UE may infer that the UE is moving. Conversely, if the current signal strength has not changed more than a signal strength change threshold, the UE may infer that the UE is stationary (not moving). In some implementations, when the UE is moving, the UE may disable or reduce the handover restraining criterion such that measurement reports may be triggered based on the reporting criterion. However, when the UE is stationary, the handover restraining criterion may be implemented to prevent a triggered measurement report that may otherwise cause an unnecessary handover.
[0035] In some implementations, the handover restraining criterion may be based on a signal quality over a time period. The signal quality may provide a further condition before sending a triggered measurement report that would otherwise cause an undesirable handover. In some implementations, the signal quality may refer to a signal-to-noise ratio (SNR) or a similar metric that is based on quality of the signal. The signal quality may be a different metric than is used with the reporting criteria of the measurement configuration. For example, the reporting criteria may use a measurement based on signal strength, while the signal quality may be based on SNR measurements over a time period. The handover restraining criterion may be based on a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the current serving cell by at least a signal quality comparison threshold over a time period. Alternatively, the handover restraining criterion may be based on a determination that the neighbor signal quality is above a signal quality precondition threshold over a time period. The signal quality comparison threshold or the signal quality precondition threshold may be a configurable value such as 2 decibels (dB) or 3 dB or 5 dB, etc. When a reporting criterion based on signal strength is satisfied, the UE may check the handover restraining criterion to confirm that the handover restraining criterion based on signal quality is satisfied. If the handover restraining criterion is not satisfied, the UE may refrain from sending the triggered measurement report that would otherwise result in an undesirable handover.
[0036] Several of the examples in this disclosure are based on the reporting criteria and triggered measurement reports described in 3GPP technical standard (TS) 38.331. For example, 3GPP TS 38.331 defines Event A3, Event A4, and Event A5 and different triggered measurement reporting events. Each of these Events A3-A5 may be triggered based on signal strength measurements (such as RSSI or RSRP). For example, Event A3 may traditionally be triggered when a neighbor cell signal strength becomes stronger, such as by an offset amount stronger, than the current serving cell. Event A4 may traditionally be triggered when a neighbor cell signal strength becomes stronger than a threshold. Event A5 may traditionally be triggered when a current serving cell signal strength becomes weaker than a first threshold and a neighbor cell signal strength becomes stronger than a second threshold. In some implementations, the handover restraining criterion based on signal quality (such as SNR) may be used as a further condition before sending a triggered measurement report for Events A3-A5. Thus, the UE may send fewer of these types of triggered measurement reports and reduce the occurrence of handovers.
[0037] In some implementations, an example handover restraining criterion may be based on a cell blacklist or cell whitelist provided by the base station. For example, the base station may provide a cell blacklist, a cell whitelist, or both, in the measurement configuration. The base station may generate the cell blacklist or cell whitelist based on a history of handover events in a particular area or between particular cells. Alternatively, or additionally, the base station may determine the cell blacklist or cell whitelist based on a deployment characteristic, such as the proximity of cells in a geography. When the cell whitelist is configured, the UE may send a triggered measurement report for neighbor cells that are identified in the cell whitelist. When the cell blacklist is configured, the UE may refrain from sending a triggered measurement report for neighbor cells that are identified in the cell blacklist.
[0038] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. Excessive handovers may cause interruptions to connectivity. The interruptions may introduce latency during a handover event, may reduce throughput or otherwise may decrease user satisfaction with the network performance. The techniques in this disclosure may mitigate excessive handovers by introducing additional criteria before a triggered measurement report is sent. The additional criteria may prevent a triggered measurement report that would otherwise result in an undesirable handover from being sent. Thus, one aim of this disclosure is to maintain an existing connection when the UE is not moving or when the signal quality of a neighbor cell does not justify a handover. The techniques in this disclosure may reduce latency, increase data throughput, and improve user satisfaction.
[0039] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication system 100. The wireless communication system 100 may include an LTE RAN or some other RAN, such as a 5G or NR RAN. The wireless communication system 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS llOd) and other network entities. A BS is an entity that communicates with user equipment (UEs) and also may be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB), an access point, a transmit receive point (TRP), or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS, a BS subsystem serving this coverage area, or a combination thereof, depending on the context in which the term is used. A UE may communicate with a base station via the downlink (DL) and uplink (UL). The DL (or forward link) refers to the communication link from the BS to the UE, and the UL (or reverse link) refers to the communication link from the UE to the BS.
[0040] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, another type of cell, or a combination thereof. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in Figure 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (for example, three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “node B,” “5GNB,” and “cell” may be used interchangeably herein. [0041] In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the BSs may be interconnected to one another as well as to one or more other BSs or network nodes (not shown) in the wireless communication system 100 through various types of backhaul interfaces, such as a direct physical connection, a virtual network, or a combination thereof using any suitable transport network.
[0042] The wireless communication system 100 also may include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, a UE or a BS). A relay station also may be a UE that can relay transmissions for other UEs. In the example shown in Figure 1, a relay station 1 lOd may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station also may be referred to as a relay BS, a relay base station, or a relay, among other examples. [0043] The wireless communication system 100 may include a heterogeneous network that includes BSs of different types, for example, macro BSs, pico BSs, femto BSs, relay BSs, among other examples. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless communication system 100.
For example, macro BSs may have a high transmit power level (for example, 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, 0.1 to 2 Watts).
[0044] A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs also may communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.
[0045] UEs 120 (for example, 120a, 120b, 120c) may be dispersed throughout wireless communication system 100, and each UE may be stationary or mobile. A UE also may be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, or a station, among other examples. A UE may be a cellular phone (for example, a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (for example, smart ring, smart bracelet)), an entertainment device (for example, a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.
[0046] Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, among other examples, that may communicate with a base station, another device (for example, remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Intemet-of-Things (IoT) devices or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE). UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, similar components, or a combination thereof.
[0001] In general, any number of RANs may be deployed in a given geographic area. Each RAN may support a particular RAT and may operate on one or more frequencies. A RAT also may be referred to as a radio technology, an air interface, among other examples. A frequency also may be referred to as a carrier, a frequency channel, among other examples. Each frequency may support a single RAT in a given geographic area in order to avoid interference between RANs of different RATs. In some cases, NR or 5G RANs may be deployed. 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with a ultra-high density (such as ~1M nodes/km2), ultra-low complexity (such as ~ 10s of bits/sec), ultra-low energy (such as -10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (such as -99.9999% reliability), ultra-low latency (such as - 1 millisecond (ms)), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (such as - 10 Tbps/km2), extreme data rates (such as multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.
[0002] The 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and the like bandwidth (BW). For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz BW. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz BW. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW.
[0003] The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with UL/downbnk scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downbnk that may be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet the current traffic needs.
[0047] In some examples, access to the air interface may be scheduled, where a scheduling entity (for example, a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity’s service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity.
[0048] Base stations are not the only entities that may function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (for example, one or more other UEs). In this example, the UE is functioning as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication. A UE may function as a scheduling entity in a peer-to-peer (P2P) network, in a mesh network, or another type of network. In a mesh network example, UEs may optionally communicate directly with one another in addition to communicating with the scheduling entity.
[0049] Thus, in a RAN with a scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.
[0050] In some aspects, two or more UEs 120 (for example, shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (for example, without using a base station 110 as an intermediary to communicate with one another). For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (which may include a vehicle-to- vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or similar protocol), a mesh network, or similar networks, or combinations thereof. In this case, the UE 120 may perform scheduling operations, resource selection operations, as well as other operations described elsewhere herein as being performed by the base station 110.
[0051] Figure 2 is a block diagram conceptually illustrating an example 200 of a base station 110 in communication with a UE 120. In some aspects, the base station 110 and the UE 120 may respectively be one of the base stations and one of the UEs in wireless communication system 100 of Figure 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T > 1 and R
[0052] At base station 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (for example, encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. The transmit processor 220 also may process system information (for example, for semi-static resource partitioning information (SRPI) or the like) and control information (for example, CQI requests, grants, upper layer signaling, among other examples.) and provide overhead symbols and control symbols. The transmit processor 220 also may generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS)) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (for example, for OFDM) to obtain an output sample stream. Each modulator 232 may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.
[0053] At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (for example, for OFDM) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.
A receive processor 258 may process (for example, demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller or processor (controller/processor) 280. A channel processor may determine RSRP, RSSI, RSRQ, channel quality indicator (CQI), among other examples. In some aspects, one or more components of UE 120 may be included in a housing.
[0054] On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (for example, for reports including RSRP, RSSI, RSRQ, CQI, among other examples) from controller/processor 280. Transmit processor 264 also may generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (for example, for DFT-s-OFDM, CP-OFDM, among other examples), and transmitted to base station 110. At base station 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller or processor (i.e., controller/processor) 240. The base station 110 may include a communication unit 244 and may communicate to the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller or processor (i.e., controller/processor) 290, and memory 292.
[0055] The controller/processor 240 of base station 110, the controller/processor 280 of UE 120, or any other component(s) of Figure 2 may perform one or more techniques associated with managing measurement gap behavior of the first connection based on an operating attribute of the second connection, as described in more detail elsewhere herein. For example, the controller/processor 280 of UE 120, or any other component(s) (or combinations of components) of Figure 2 may perform or direct operations of, for example, processes 600, 700, 800 1001 or 1002 of Figures 6, 7, 8, 10A or 10B, respectively, or other processes as described herein. The memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively. The stored program codes, when executed by the controller/processor 280 or other processors and modules at UE 120, may cause the UE 120 to perform operations described with respect to processes 600, 700, 800, 1001 or 1002 of Figures 6, 7, 8, 10A or 10B, respectively, or other processes as described herein. A scheduler 246 may schedule UEs for data transmission on the downlink, the uplink, or a combination thereof.
[0056] While blocks in Figure 2 are illustrated as distinct components, the functions described above with respect to the blocks may be implemented in a single hardware, software, or combination component or in various combinations of components. For example, the functions described with respect to the transmit processor 264, the receive processor 258, the TX MIMO processor 266, or another processor may be performed by or under the control of controller/processor 280.
[0057] Figure 3 shows a block diagram conceptually illustrating an example wireless communication system 300 in which a UE may have dual connectivity (DC). The wireless communication system 300 includes a UE 120, an LTE RAN 320, a 5GNR RAN 360, an EPC 330, and a packet network 340. The UE 120 may include components (not shown), such a wireless communication module and a connection controller, among other examples. In some implementations, a single chip or component of the UE 120 may provide the wireless communication module and the connection controller and may communicate via one or more radio components of the UE 120. The wireless communication module may be capable of establishing an LTE connection (anchor connection) with an eNB 310 of the LTE RAN 320 and establishing a 5GNR connection (secondary connection) with a gNB 350 of the 5GNR RAN 360. For brevity, the description refers to the UE 120 making these connections. The UE 120 may refer to a portable electronic device or to one or more components of the portable electronic device.
[0058] The LTE RAN 320 may be an evolved universal terrestrial radio access network (E- UTRAN) and is just one example RAT that may be used for an access stratum of the wireless communication system 300. The EPC 330 is just one example of a core network that may be used in a non-access stratum of the wireless communication system 300. The 5G NR RAN 360 may use the same EPC 330 as the LTE RAN 320. Alternatively, the 5G NR RAN 360 may use a 5G Core (5GC) 370 with a 5G Core Access and Mobility Management Function (AMF) that performs similar functionality as the Mobility Management Entity (MME) 335 of the EPC 330. The 5GC 370 may connect to the packet network 340. In some deployments, the same packet network 340 may provide access to services such as Internet access, an IP multimedia subsystem (IMS) service, or other services. The example in Figure 3 is described with reference to an E- UTRAN - NR dual connectivity (EN-DC) configuration in which the LTE RAN 320 and the NR RAN 360 utilize the same EPC 330 of the wireless communication system 300.
[0059] Using EN-DC, the LTE RAN 320 and the 5G NR RAN 360 may be used to establish multiple radio connections with the same UE 120. The UE 120 may establish a first radio connection (LTE connection 312) with an eNB 310 of the LTE RAN 320. Establishing the first radio connection may include the UE 120 sending an RRC Setup Request message to the eNB 310 and receiving an RRC Setup message from the eNB 310. Once the LTE connection 312 is connected, the UE may setup a default packet bearer to the EPC 330. For example, the UE 120 may send an attach request message to the MME 335 in the EPC 330. The MME 335 may respond with an attach accept message that sets up the default packet bearer. The default packet bearer may be referred to as a default EPS bearer and may be used to communicate with the MME 335 or other elements in the EPC 330. The default packet bearer may be used to setup other bearers or services provided by the wireless communication system 300. For example, the UE may send packet data via the default packet bearer to a data packet gateway (P-GW) 345 in the EPC 330 that connects to the packet network 340.
[0060] After establishing the LTE connection 312, the UE 120 may establish a second radio connection (5G NR connection 352) with a gNB 350 of the 5G NR RAN 360. The second radio connection may be established by the wireless communication system. For example, the eNB 310 may determine that the UE 120 is authorized to utilize EN-DC and may activate a bearer via the gNB 350. The eNB 310 may send an RRC Connection Reconfiguration message to the UE 120 to inform the UE 120 of the second radio connection. Thereafter, the UE 120 may be in an RRC connected mode that includes radio connections to both the eNB 310 and the gNB 350.
The eNB 310 may be referred to as a master node (MN). The gNB 350 may be referred to as a secondary node (SN).
[0061] Each base station may operate multiple cells. In some traditional deployments, a base station may operate three (3) cells, but other quantities of cells may be deployed at a base station. A master cell group (MCG) may include a primary cell (PCell) and zero or more secondary cells (SCells) of the eNB 310. A secondary cell group (SCG) may include a primary SCG cell (PSCell) and zero or more secondary cells (SCells) of the gNB 350. Once an SCG is added to the RRC configuration, the UE 120 may be in an NS A mode of operation. Any of cells within the MCG or SCG may be referred to as a current serving cell. For Dual Connectivity operation, the term Special Cell (SpCell) refers to the PCell of the MCG or the PSCell of the SCG.
[0062] Once the UE 120 is in an RRC connected mode, the UE 120 may perform neighboring cell measurements and measurement reporting. For example, either or both of the eNB 310 or the gNB 350 may provide a measurement configuration to the UE 120 in an RRC message. The measurement configuration may include reporting criterion for triggering a measurement reporting event based on a signal measurement of a neighbor cell. Several types of standard measurement reports are defined by the 3 GPP 38.331 technical standard. Three of the measurement reporting events (referred to as Event A3, Event A4, and Event A5) are described in several examples of this disclosure. A measurement reporting event occurs when a corresponding reporting criterion is satisfied for a time period. For example, Event A3 triggers a measurement report when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than the SpCell by at least an offset amount. Event A4 triggers a measurement report when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a threshold. Event A5 triggers a measurement report when the SpCell becomes worse (such as weaker signal strength or lower signal quality) than a first threshold (thresholdl) and a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a second threshold (threshold2). For the purpose of these measurement reporting events, the SpCell may be the PCell or the PSCell. The premise of these triggered measurement reports is for the UE 120 to inform the base station when a neighbor cell may provide a better service for the UE 120. In response, the base station may perform a handover to the neighbor cell. The handover may include some network-side reconfiguration, such as transferring bearers and changing a registration status of the UE 120, as well as UE-to-network reconfiguration, such as the eNB 310 sending an RRC Connection Reconfiguration message to the UE 120. The RRC Connection Reconfiguration message may include changes to the MCG or SCG as part of the handover.
[0063] Often, a UE 120 may be within overlapping coverage areas of different base stations. When the signal strengths of a neighboring cell and a serving cell are similar (such as within 2 to 3 dB, or 1-5 dB, etc.), it is possible for a UE to experience repetitive triggered measurement reports resulting in a ping-pong situation with undesirable handovers between two or more cells. Excessive handovers also may occur more frequently in 5G NR networks. In 5G NR, reliable handover mechanisms in urban environments remains a challenge. In some instances, network operators may deploy base stations and turn them on and off in a coordinated manner to save energy. As a result, radio channel conditions may change dramatically for the mobile users and so the neighboring cell list changes rapidly. This also may result in increased interference and high energy consumption of the network, frequent handovers, unnecessary handovers with ping- pong effect, increased handover failure and delay. If a device undergoes multiple handovers, the handover delay may accumulate, resulting in a severe deterioration to the user experience.
[0064] In 5G field testing, a common observation is that the UE experiences frequent ping- pong handovers. In the 5G NR network, the maximum cell number may reach about 1008 cells in each operating frequency and a cell transmits synchronization signal by SSB, in which the UE can detect many equivalent RSRP level cells by the characteristics of each directional SSB and significantly large 5G cell deployments. In this regard, the UE may trigger frequent ping-pong handover in mobility or by the UE itself in a direction change when the network configures a relatively low cell level hysteresis margin and measurement offset. This can increase both the UE and network signal message transmission loading, resulting in a decrease of UE performance such as throughput, latency, and power. Using one or more techniques in this disclosure, a ping- pong situation with excessive handovers may be prevented or mitigated using a handover restraining criterion in addition to (or as a modification of) a reporting criterion associated with a triggered measurement report that would otherwise initiate a handover. [0065] Figure 4 shows a pictorial diagram conceptually illustrating an example of a UE experiencing a ping-pong situation with excessive handovers. Figure 4 depicts a wireless communication system 400 similar to the wireless communication system 300 described with reference to Figure 3. The wireless communication system 400 includes a UE 120 using EN-DC in which the UE 120 has an LTE connection 312 with an eNB 310 and a 5GNR connection 352 with a gNB 350. As described with reference to Figure 3, the RRC configuration for the connections may include a measurement configuration with triggered measurement reporting events. Each triggered measurement reporting event may have a reporting criterion and a set of configurable parameters. The reporting criterion may be satisfied based on whether an inequality is met. The reporting criterion and parameters for Event A3, Event A4, and Event A4 are further described with reference to Figure 8. However, as an example to illustrate a ping pong situation, Event A3 is briefly described here. The inequality for entering Event A3 is as follows:
Mn + Ofh + Ocn - Hys > Mp + Ofp + Ocp +Off (1)
Thus, the reporting criterion for Event A3 is satisfied when the inequality (1) is true. The reporting criterion for Event A3 is not satisfied when the inequality (1) is not true. The variables in the formula are defined as follows:
• Mn is the measurement result of the neighboring cell, not taking into account any offsets.
• Ofn is the measurement object specific offset of the reference signal of the neighbor cell.
• Ocn is the cell specific offset of the neighbor cell, and set to zero if not configured for the neighbor cell.
• Mp is the measurement result of the SpCell, not taking into account any offsets.
• Ofp is the measurement object specific offset of the SpCell.
• Ocp is the cell specific offset of the SpCell, and is set to zero if not configured for the
SpCell.
• Hys is the hysteresis parameter for this event.
• Off is the offset parameter for this event.
• Mn, Mp are expressed in dBm in case of RSRP, or in dB in case of RSRQ and RS- SINR.
• Ofn. Ocn, Ofp, Ocp, Hys, Off are expressed in dB.
Each of these variables may be indicated in the measurement configuration provided by a base station to the UE. Either (or both) of the eNB 310 or the gNB 350 may provide a measurement configuration. In some implementations, the measurement configuration may indicate a timeToTrigger parameter that indicates a time during which specific criteria for the event needs to be met in order to trigger a measurement report. Thus, the reporting criteria must be satisfied for the timeToTrigger time duration.
[0066] In an example deployment, the Off may be set to 1 dB and the Hys also may be set to 1 dB. Thus, the effect of the Off and the Hys in the inequality (1) may be disregarded since they equally adjust both sides of the inequality (1). Similarly, in some implementations, the effect of the Ofn, the Ofp, and the Ocp may not modify the outcome of the inequality (1). Thus, in its shortest form, the inequality (1) that triggers the Event A3 report may occur when the measurement result of the neighboring cell is greater than the measurement of the SpCell.
[0067] Referring back to Figure 4, the UE 120 may periodically perform measurements of neighbor cells, such as other cells of gNB 350 or of another gNB 450. The measurements of the neighbor cells may be close (such as within 1-2 dB, 1-5 dB, etc.) to the measurement of the SpCell. The SpCell refers to either the PCell of the MCG or the PSCell of the SCG. Taking the SpCell of the SCG as an example, the UE 120 may compare the measurement results of the neighbor cell 452 of the gNB 450 with the measurement results of the existing PSCell used for the 5GNR connection 352 with the gNB 350. If the measurement of the neighbor cell 452 is greater than the measurement results of the PSCell, the Event A3 report may be triggered. The UE 120 may send the triggered Event A3 report to the gNB 450, causing the gNB 350 to reconfigure the RRC configuration to remove the serving cells of the gNB 350 from the SCG and instead make the neighbor cell 452 of the gNB 450 the PSCell of the updated SCG. Thus, the gNB 350 may perform a handover from the gNB 350 to the gNB 450. While this procedure is normally desirable, what could happen is that soon after changing the RRC configuration to handover the 5G NR connection to the gNB 450, the UE 120 may discover that the Event A3 report is triggered again - this time indicating that the gNB 350 has a stronger measurement than the previous neighbor cell 452 (which has become the SpCell of the updated SCG). Thus, the UE 120 may send another Event A3 report (this time to the gNB 450), causing the gNB 450 to reconfigure the RRC again and perform a handover back to the gNB 350.
[0068] The cycle may continue repetitively while the UE 120 remains in a location where the signals from neighbor cells (such as from both the gNB 350 and the gNB 450) have similar measurement results repetitively triggering the inequality (1) for the Event A3 report. Although the example of Figure 4 is described with reference to Event A3, a similar ping-pong situation may occur with the inequalities associated with Event A4 and Event A5.
[0069] A ping-pong situation may be detected based on a frequency of handovers in a recent time period. For example, the frequency of handovers may be determined based on n count of handovers triggered within a time duration tl. The UE 120 may detect a ping-pong situation when, for example, there are at least four (4) handovers within an approximately 20 second duration. Excessive handovers may reduce downlink throughput and network performance. For example, the time associated with RRC reconfiguration may cause latencies and disrupt communication. When a ping-pong situation is detected by the UE 120, the UE 120 may use one or more techniques to suppress or further precondition the sending of triggered measurement reports. For example, the UE 120 may evaluate whether a handover restraining criterion is satisfied before sending a triggered measurement report. The handover restraining criterion may limit the occurrence of triggered measurement reporting events that would otherwise result in a further handover.
[0070] Figure 5 shows a signaling diagram illustrating a handover process 500. The handover process 500 may include a first BS 110A, a second BS 110B, and a UE 120, which may be examples of the corresponding devices described with reference to Figures 1-4.
[0071] The handover process 500 may be implemented by the first BS 110A as a source BS serving the UE 120 in a serving cell (also referred to as a source cell), the second BS 110B as a target BS in a target cell, and a NR core network including a user plane function (UPF) component 502 and an access and mobility management function (AMF) component 504. The source BS and the target BS are in communication with the core network for mobility support and user plane functions. Steps of the handover process 500 can be executed by computing devices (such as, a processor, processing circuit, or other suitable component) of the source BS, the UE 120, the target BS, the UPF component 502, and the AMF component 504. As illustrated, the handover process 500 includes a number of enumerated steps, but implementations of the handover process 500 may include additional steps before, after, and in between the enumerated steps. In some implementations, one or more of the enumerated steps may be omitted or performed in a different order. In the following description of the handover process 500, the operations between the first BS 110A, second BS 110B, and the UE 120 may be transmitted in a different order than the example order shown, or the operations performed by the BSs 110 and the UE 120 may be performed in different orders or at different times. Certain operations also may be left out of the handover process 500, or other operations may be added to the handover process 500.
[0072] In this example a handover between the first BS 110A and the second BS 110B is an inter-CU (centralized unit) handover, using a DC handover, in which both the first BS 110A and the second BS 110B are associated with a different CU. In some examples, the handover process 500 may commence at block 505 with the first BS 110A establishing a first connection with the UE 120 (such as, performing a cell acquisition procedure, a random access procedure, an RRC connection procedure, an RRC configuration procedure, etc.). [0073] At block 507, the UE may perform a measurement procedure that may include performing channel measurements. Such may include, for example, signal measurements of neighboring BSs by the UE 120 to identify one or more neighboring BSs that may be candidates for the handover procedure. The measurements may include a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSSI), or a signal-to-interference-noise-ratio (SINR), among other examples.
[0074] At block 510, the UE 120 may detect a measurement reporting event for which a reporting criterion is satisfied based on the signal measurements. In some cases, the measurement event may be a signal measurement (such as, a reference signal received power (RSRP)) of the first BS 110A dropping below a threshold value by a predetermined measurement offset, may be a time-based periodic event, or combinations thereof. As described herein, the measurement reporting event may be further regulated or restricted based on a handover restraining criterion. In some implementations, the handover restraining criterion may be used in addition to the reporting criterion. Alternatively, or additionally, the handover restraining criterion may be based on overriding a parameter of the reporting criterion.
[0075] At block 515, the UE 120 may transmit a measurement report to the first BS 110A, and the measurement report may indicate that the second BS 110B is a candidate BS for a handover. As such, the first BS 110A may prepare for a handover. The measurement report may include measurements about the quality of the channel between the UE and the source BS. In some cases, the UE 120 may send the measurement report indicating the measurement reporting event (such as, an A3 measurement report in the NR system). Based on the measurement report, the first BS 110A may consider that another better neighbor cell (such as, the second BS 110B) is detected if the A3 measurement report is received within a certain time from the UE 120. In other cases, a new measurement event (such as, an A3 measurement event) may be defined, which is to report when a neighbor cell is detected to be stronger than the first BS 110A and the second BS 110B.
[0076] At block 520, the first BS 110A may make a handover decision to handover the UE 120 from the first BS 110A to the second BS 110B. In some cases, the first BS 110A may make the handover decision based on the measurement report provided by the UE 120, one or more threshold values for initiating a handover, a differential in one or more signal measurements from one or more prior measurement reports, one or more measurement reports from other UEs, or any combinations thereof. The first BS 110A may coordinate with the second BS HOB to prepare for a handover (HO), for example, based on the measurement report indicating that the signal quality of the first BS 110A is lesser than the signal quality of the second BS HOB. As part of the handover preparation, the first BS 110A may request the second BS 110B to prepare for the handover. The first BS 110A may communicate the UE’s radio resource control (RRC) context information or other UE’s configurations to the second BS 110B. The second BS 110B may prepare for the handover by reserving resources for the UE 120. After reserving the resources, the second BS 110B may transmit an acknowledgement to the first BS 110A in response to the handover request.
[0077] In the example of Figure 5, the first BS 110A may determine that the UE 120 is to be handed over to the second BS 110B. Further, the first BS 110A may determine that the UE 120 has a dual-connectivity (DC) capability and may generate a decision to perform a DC-based handover of the UE 120. For example, the first BS 110A (or an associated CU) may select from possible handover procedures that may be performed by UE 120 based at least in part on the indicated capability of UE 120. In the example of Figure 5, the first BS 110A may select an DC handover procedure for UE 120 based at least in part on UE 120 indicating a DC capability. In other examples, the first BS 110A may select a make-before-break handover procedure or a different handover procedure (such as, a legacy handover procedure), and different operations associated with the selected handover procedure may be performed.
[0078] At block 525, the first BS 110A and the second BS 110B may initiate a role switch negotiation procedure. In some examples, the first BS 110A may transmit a role switch request to the second BS 110B. The role switch request may indicate that the second BS HOB is to switch to be the master node in the DC connection with the UE 120 once the connection between the UE 120 and the second BS is established, and the first BS 110A is to switch to be the SN connection. The second BS HOB may receive the role switch request and identify that the UE 120 is to be handed over to the second BS HOB, and transmit a role switch acknowledgment at block 540.
[0079] In some aspects, the first BS 110A may transmit a secondary node (SN) addition request to the second BS HOB. The SN addition request may be provided based on the DC handover decision to establish a DC connection between both the first BS 110A and the second BS HOB and the UE 120. The initial connection between the first BS 110A and the UE 120 in such cases is a master node (MN) connection and the second BS HOB may be added initially as a SN based on the SN addition request. The second BS HOB may transmit a SN addition acknowledgment to the first BS 110A to acknowledge that the second BS HOB received, and that may indicate an ability to serve UE 120 after the handover procedure. In some cases, the role switch request may be combined with the SN addition request, and the role switch acknowledgment may be combined with the SN addition acknowledgment. In such cases, signaling between the first BS 110A and the second BS 110B may be reduced. In some aspects, the role switch request and the role switch acknowledgment may be optional operations, and may be skipped in cases where the SN addition request also includes the role switch request, and the SN addition acknowledgment also includes the role switch acknowledgment.
[0080] At block 545, the first BS 110A may transmit a RRC reconfiguration message to the UE 120. The RRC reconfiguration message may include a handover command instructing the UE 120 to handover from the first BS 110A to the second BS 110B, in which a handover execution phase begins. The handover command may include information associated with the second BS 110B, for example, a random access channel (RACH) preamble assignment for accessing the second BS 110B. During the handover execution phase, the UE 120 may execute the handover by performing a random access procedure with the second BS 110B.
[0081] In some aspects, the RRC reconfiguration message may indicate to the UE 120 that a connection with the second BS 110B is to be established according to a DC connection establishment procedure. For example, the RRC reconfiguration may indicate that UE 120 is to perform DC handover procedure with second BS 110B using the DC capability of UE 120. In some aspects, the RRC reconfiguration can include information identifying second BS 110B, information identifying a handover configuration, identifying a DC configuration, or combinations thereof. For example, in some cases, the RRC reconfiguration message may provide an indication of a secondary cell group associated with the second BS 110B that is to be configured as part of the DC based handover, and also indicate the source cell group identification of the first BS 110A.
[0082] Following the transmission of the RRC reconfiguration at block 545 and until a second connection with the second BS 110B is established, downlink data that is to be transmitted to the UE 120 may be provided to the first BS 110A (such as, from the UPF component 502 at the core network), and the first BS 110A may transmit the downlink data to the UE 120 via the first connection. Similarly, uplink data transmitted from the UE 120 may be transmitted to the first BS 110A via the first connection. In some cases, the first BS 110A may forward downlink user data to the second BS 110B.
[0083] In some cases, at block 546, the UE 120 may configure a SN based on the RRC reconfiguration based on a DC connection procedure, and may transmit an RRC reconfiguration complete indication to the first BS 110A to indicate that the second connection is being established. During the establishment of the second connection with the second BS HOB, the UE 120 may maintain the first connection with the first BS 110A, and thus have an active established connection during the handover, as indicated at block 597. As part of the DC connection procedure, at block 547, the first BS 110A may transmit a SN reconfiguration complete indication to the second BS HOB that may indicate that the UE 120 is configuring the second connection. [0084] At block 550, the UE 120 and the second BS 110B may perform a random access procedure to establish a second connection with the second BS 110B. The random access procedure may be performed according to established random access procedures (such as,
RACH procedures that are established in LTE or NR). Upon completion of the random access procedure and establishment of the second connection, the UE 120 may, at block 555, transmit a RRC reconfiguration complete indication to the second BS 110B. At this point, the second BS 110B may be the master node in the DC connection with both the first BS 110A and second BS 110B, and thus the second connection is the primary link as indicated at block 560. In some cases, the UE 120 may transmit a packet data convergence protocol (PDCP) status transfer and uplink user data to the second BS 110B via the second connection. In some aspects, after the RRC reconfiguration is complete, the UE 120 may perform uplink user/control plane duplication with the first BS 110A. For example, control plane data may be duplicated and shared between the first BS 110A and the second BS 110B. Accordingly, UE 120 may achieve improved reliability when receiving the data on the downlink.
[0085] In some aspects, the second BS HOB may transmit a role switch complete indication to the first BS 110A. In some cases, the role switch complete indication may provide an indication to the first BS 110A (such as, via an Xn backhaul link) that the second connection has been established with the UE 120, and that signaling radio bearers (SRBs) and data radio bearers (DRBs) have been established in the second connection. In some implementations, the first BS 110A may transmit a SN status transfer to the second BS 110B. The SN status transfer may provide the most up to date PDCP status and downlink sequence number to use, for example.
The SN status transfer also may indicate to the second BS HOB that the first connection with the first BS 110A may be released in accordance with the DC handover procedure.
[0086] At block 575, the second BS 110B may generate a handover complete decision and determine that the first connection with the first BS 110A may be released. At block 580, the second BS HOB, responsive to determining that the handover is complete, may transmit a RRC reconfiguration request to the UE 120 to release the first connection with the first BS 110A. In some cases, the second BS HOB may provide a handover completion indication to the UPF component 502 in the core network. Additionally or alternatively, the second BS HOB may transmit a PDCP status transfer to the UE 120.
[0087] At block 585, the UE 120 may release the first connection with the first BS 110A.
The UE 120 may release the first connection, for example, by removing DRBs and SRBs associated with the first BS 110A, and PDCP status and sequence numbers associated with the first connection. [0088] At block 590, the UE 120 may transmit a RRC reconfiguration complete indication to the second BS 110B to indicate that the first connection has been released.
[0089] At block 592, the second BS 110B, the UPF component 502, and the AMF component 504 may coordinate to switch the user-plane (U-plane) path of the UE 120 from the first BS 110A to the second BS 110B. Until this point of time, the DL data transmission for the UE 120 is still being routed to the first BS 110A. In some cases, the second BS 110B may transmit a path switch request to the AMF component 504 of the core network, and the AMF component 504 and the UPF component 502 may perform a path switch related to core network internal signaling to provide the actual downlink path used to the UPF for subsequent downlink data transmissions. Further, in some cases, in the event that the first BS 110A received fresh downlink data for the UE 120 prior to the path switch at the UPF component 502, the first BS 110A may transmit the fresh downlink data to the second BS 110B for downlink transmission to the UE 120. In some cases, the AMF component 504 may provide a path switch request acknowledgment to the second BS 110B. Following the path switch acknowledgment, the second BS 110B may transmit a UE context release command to the first BS 110A, and the first BS 110A may release UE context for the first connection and transmit a UE context release complete back to the second BS 110B.
[0090] At block 594, the AMF component 504 transmits an end mark message to the first BS 110A after the U-plane path is switched. For example, the AMF component 504 may provide an end marker to the first BS 110A to indicate that the downlink path has been changed to the second BS HOB, and the first BS 110A may provide an indication to the second BS 110B that the end marker has been received.
[0091] At block 595, responsive to the indication that the first connection is released handover completion may be performed.
[0092] In some aspects, UE 120 may use a dual protocol stack, which includes a source protocol stack for communicating with first BS 110A and a target protocol stack for communicating with second BS 110B. Each of these protocol stacks may include a PDCP layer, a radio link control (RLC) layer, a medium access control (MAC) layer, or a physical (PHY) layer. In some aspects, the source protocol stack and the target protocol stack may share one or more layers, such as a PDCP layer. In some aspects, the target protocol stack may be used for uplink data transmissions.
[0093] Figures 6-11 describe example operations for processes that utilize handover restraining criterion in addition to (or as modification of) a reporting criterion. The example operations of the processes may be implemented by a UE or its components as described herein. For example, the processes described with reference to Figures 6-11 may be performed by an apparatus such as UE 120 described with reference to Figures 1-5 or a wireless communication device such as the wireless communication device 1400 described with reference to Figure 14. [0094] Figure 6 shows a flowchart illustrating an example process for triggered measurement reports using a handover restraining criterion.
[0095] At block 610, the apparatus may establish at least a first connection with a serving cell of a base station (BS).
[0096] At block 620, the apparatus may receive a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based, at least in part, on one or more network-provided parameters and a signal measurement of a neighbor cell, wherein the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell.
[0097] At block 630, the apparatus may monitor for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based, at least in part, on a UE-configured parameter different from the one or more network-provided parameters. [0098] At block 640, the apparatus may communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied. The handover restraining criterion may be one or more of the examples described herein, including any combination thereof. The apparatus may send the triggered measurement report when it determines that both the reporting criterion and the handover restraining criterion have been satisfied. Thus, the handover restraining criterion may limit the triggered measurement reports that would otherwise be sent using the reporting criterion. In some implementations, the handover restraining criterion is based on a modification to the reporting criterion to override a parameter (such as a measurement offset value) of the reporting criterion.
[0099] Figure 7 shows a flowchart illustrating an example process 700 with example handover restraining criteria. At block 710, the apparatus may determine a signal measurement of a neighbor cell. For example, the signal measurement may be an RSRP, RSRQ or SINR of the neighbor cell.
[0100] At block 720, the apparatus may determine if the signal measurement satisfies a reporting criterion for a measurement reporting event. If the signal measurement does not satisfy the reporting criterion, the process may return to block 710 to check another signal measurement or another neighbor cell. If the signal measurement does satisfy the reporting criterion, the process may continue to block 730. [0101] At block 730, the apparatus may determine a handover restraining criterion. In some implementations, the handover restraining criterion may depend on whether a ping-pong situation has been detected. A ping-pong situation may be detected with a frequency of handovers is above a threshold. In some implementations, apparatus may determine whether the frequency of handovers falls within a high frequency category, a medium frequency category, or a normal frequency category. In some implementations, the frequency of handovers (or the high frequency category, medium frequency category, or normal frequency category) may impact which handover restraining criteria are used in block 730 or configurable parameters of a handover restraining criterion.
[0102] Several example handover restraining criteria are shown in Figure 6. For example, at block 740, the apparatus may determine the frequency of handovers. At block 750, the handover restraining criterion may be based on a delay timer. The delay timer is different from the timeToTrigger parameter which is associated with a measurement configuration for an Event.
The delay timer is used prevent a new measurement report from being sent for a time period since a last handover event. In some implementations, the duration of the delay timer may depend on the frequency of handovers. The handover restraining criterion may be satisfied when the delay timer expires. For example, the delay timer may be implemented as a countdown timer that is initiated after a previous handover. When the countdown timer reaches zero the delay timer is expired and the handover restraining criterion is satisfied.
[0103] In another example, at block 760, the handover restraining criterion may be based on a signal quality comparison. For example, handover restraining criterion may require the signal quality of the neighbor cell to be better (such as a higher quality) than the signal quality of the SpCell by at least a threshold amount and for a time period. The handover restraining criterion may be satisfied when the neighbor cell’s signal quality is at or above the threshold amount for the time period. In another example, at block 770, the handover restraining criterion may be based on a signal quality precondition. For example, the handover restraining criterion may be satisfied when the signal quality of the neighbor cell is better (such as a higher quality) than a signal quality threshold for a time period. At block 780, the handover restraining criterion may be based on UE movement. The handover restraining criterion may be satisfied or relaxed when the UE determines that the UE is changing location relative to a base station. For example, when the UE is moving (such as changing locations), the handover restraining criterion may easier to satisfy than when the UE is stationary.
[0104] In some implementations a movement speed (such as a rate of distance traveled over time) may impact the handover restraining criterion. For example, a duration of the delay timer may depend on the movement speed. The duration may be set to a first value when the UE stationary, set to a second value when the UE is non-stationary and the movement speed of the UE is lower than a speed threshold, or set to a third value when the UE is non-stationary and the movement speed of the UE is higher than the speed threshold. The second value may be lower than the first value and the third value lower than the second value. Thus, the duration of the delay timer may decrease as the movement speed of the UE increases. Additionally, or alternatively, a parameter (such as a signal measurement offset value) of the handover restraining criterion may be adjusted based on the movement speed of the UE. A higher signal measurement offset value may restrain more handovers and may be used when the movement speed of the UE is lower than the speed threshold. A lower signal measurement offset value may restrain less handovers and may be used when the movement speed of the UE is higher than the speed threshold lower.
[0105] At block 780, the apparatus may determine the UE movement and determine which, if any, of the handover restraining criteria in block 730 to use. In some implementations, the operations of block 730 and the use of a handover restraining criterion may be dependent on a determination that the UE is stationary.
[0106] At block 790, the apparatus may determine whether the handover restraining criterion is satisfied. If the handover restraining criterion is satisfied, the process 700 continues to block 795 in which the apparatus may send the triggered measurement report. Otherwise, if the handover restraining criterion is not satisfied, the process 700 may return to block 710.
[0107] Figure 8 shows a flowchart illustrating an example process 800 using a combination of handover restraining criteria. The example handover restraining criteria in Figure 6 may be combined or structured in an order. For example, the frequency of handovers and the UE movement may be used to determine the duration of a delay timer. The example process 800 provides an example combination and structure of multiple handover restraining criteria.
[0108] At block 810, the apparatus may determine a frequency of handovers. The frequency of handovers may be a count n of handovers triggered during a time period t.
[0109] At block 820, the apparatus may determine a duration of a delay timer based on the frequency of handovers. For example, the duration of the delay timer may increase linearly or exponentially in relation to the frequency of handovers. As an example, the duration of the delay timer may be from 1-20 seconds (s). In some implementations, the apparatus may determine a high duration (such as 20 s) for the delay timer if the frequency of handovers fall in a high frequency category (such as more than 6 handovers in the preceding 5 s). The apparatus may determine a medium duration (such as 10 s) for the delay timer if the frequency of handovers fall in the medium frequency category (such as 2-5 handovers in the preceding 5 s). The apparatus may determine a zero or nominal duration (such as 1 s) for the delay timer if the frequency of handovers fall in the normal frequency category (such as less than 2 handovers in the preceding 5 s). The values of the delay timer durations and thresholds for the handover frequency categories may be configurable parameters.
[0110] In some implementations, the thresholds for the handover frequency categories may be expressed as an average or running average. For example, UE may determine the frequency of handovers an average ratio of handovers over a time period. The high frequency category may refer to an average of more than 1 handover per second. The medium frequency category may refer to an average of approximately 1 handover per second (or a range such as 0.5-1.5 handovers per second). The normal frequency category may refer to an average of less than approximately 1 handover per second. In some implementations, the UE may determine that the frequency of handovers is in the high frequency category after consecutive instances of utilizing the delay timer duration associated with the medium frequency category.
[0111] At block 830, the apparatus may determine a change in signal strength for the current serving cell (such as the SpCell). For example, the apparatus may determine the current RSRP, current RSSI, or current SINR measured for the current serving cell and compare it to a previous corresponding measurement for the current serving cell.
[0112] At block 840, the apparatus may determine whether the change in signal strength indicates the UE is moving. For example, when the UE is changing locations relative to a base station, the RSRP, RSSI, or SINR also may change. A change in the RSRP, RSSI, or SINR may be used to infer whether the UE is moving. When the change or variation of the signal strength is above a signal strength change threshold, the apparatus may infer that the UE is moving. Conversely, when the change or variation of the signal strength is below the signal strength change threshold, the apparatus may infer that the UE is stationary. If the UE is moving, the process 800 may continue to block 860. If the UE is stationary, the process 800 may continue to block 850.
[0113] At block 850, the apparatus may start a delay timer after a handover event. The duration of the delay timer is the duration determined in block 820. Thus, when the UE is stationary, the delay timer will be a handover restraining criterion that prevents the apparatus from sending a triggered measurement report until after the delay time expires. After the delay time expires, if the reporting criterion is satisfied, the apparatus may send a triggered measurement report.
[0114] At block 860, the apparatus may disable the delay timer or reduce the duration of the delay timer. In some implementations, block 860 is performed when the UE is moving. Thus, the usefulness of performing a handover may outweigh the advantage of using a handover restraining criterion to prevent a handover. [0115] Figure 9 shows a diagram illustrating an example of a signal measurement plot over time and corresponding behavior to enable or disable a handover restraining criterion. In some implementations, the handover restraining criterion may be enabled (to restrict excessive handovers) when a signal measurement of the serving cell is above a first signal strength threshold 910 (referred to as “RSRP High Threshold” in some examples). The handover restraining criterion may be disabled (for more permissive handover behavior) when a signal measurement of the serving cell is below a second signal strength threshold 920 (referred to as “RSRP Low Threshold” in some examples). The first signal strength threshold 910 and the second signal strength threshold 920 may provide a hysteresis range during which changes to the handover restraining criterion may be kept stable to prevent frequent enablement or disablement. [0116] The received signal measurement plot 900 includes a signal measurement 902 of a transmission signal from a BS. The signal measurement plot 900 indicates that the signal measurement 902 varies in RSRP values over time. For example, at time A, the signal measurement 902 has an RSRP value that is greater than the first signal measurement threshold 910. At time A, the UE may enable the handover restraining criterion. In some implementations, enabling the handover restraining criterion may include overriding a network- provided parameter (such as an offset value in the reporting criterion) with a higher value. The handover restraining criterion may be enabled for at time period (shown as box 904) between time A and time B.
[0117] At time B, the RSRP value of the signal measurement 902 falls below the second signal strength threshold 920. As a result, the UE may disable the handover restraining criterion (shown at arrow 906). The handover restraining criterion may be disabled for at time period (shown as box 909) between time B and time C. Between time B and time C, the RSRP value of the signal measurement 902 begins increasing, until the RSRP value exceeds the first signal measurement threshold at time C. At time C, the UE may once again enable the handover restraining criterion (shown at arrow 912). The handover restraining criterion may be enabled for at time period (shown as box 908) from time C as long as the RSRP value of the signal measurement 902 remains above the second signal strength threshold 920.
[0118] In view of the received signal measurement plot 900, the UE can avoid (or restrain) ping-pong handover when the RSRP value of the serving cell is greater than the RSRP High Threshold. Conversely, the UE can disable the handover restraining criterion to trigger a relatively fast measurement report when the RSRP value of the serving cell is lesser than the RSRP Low Threshold. At any time that the RSRP value of the serving cell is between the RSRP High Threshold and the RSRP Low Threshold, the UE may maintain the enablement or disablement state of the handover restraining criterion. Thus, the RSRP High Threshold and the RSRP Low Threshold may provide stability to prevent frequent enablement or disablement changes to the handover restraining criterion.
[0119] Figure 10A shows a flow diagram of an example process 1001 for monitoring for an occurrence of a measurement reporting event. The process 1001 starts at block 1010, where the UE enters a connected mode on aNR cell (such as, the BS 105). At block 1012, the UE receives a measurement configuration from the BS. The measurement configuration includes a reporting criterion for a measurement reporting event. The reporting criterion may be based on one or more network-provided parameters (such as a first signal measurement offset). In some aspects, the UE receives the measurement configuration in a radio resource control (RRC) message. The measurement configuration instructs the UE to obtain signal measurements of a plurality of reference signals from a base station (BS) and one or more neighbor cells and send a triggered measurement report when the reporting criterion is satisfied.
[0120] At block 1016, the UE determines whether a network-provided parameter in the reporting configuration needs to be changed. For example, the reporting criterion may include a first signal measurement offset (such as, A3 offset provided by the network for an A3 event configuration). The UE may determine whether the A3_offset needs to be overridden with a different signal measurement offset (such as, a user-configurable override_A3_offset) in a handover restraining criterion. In some implementations, the handover restraining criterion may act as an override of the reporting criterion when one or more parameters are changed to make the modified reporting criterion more stringent than the original reporting criterion. For example, the first signal measurement offset may be overridden with a higher value. The decision in block 1016 may be based on how many handovers have been detected in over a recent time period. For example, if the UE is experiencing a ping-pong condition, the UE may decide that the network-provided parameter in the reporting configuration needs to be changed.
In another example, the UE may determine whether the A3_offset plus a hysteresis margin (such as 1 dB) is less than an override threshold value (such as 3 dB). As an example, if the A3_offset is 1 dB, then sum of the A3_offset and the hysteresis margin would be 2 dB, which is less than the 3 dB override threshold value. In such case, the UE may decide that the network-provided parameter in the reporting configuration needs to be changed. If the decision in block 1016 is to change the network-provided parameter, the process continues to block 1020. Otherwise, if the decision is that the network-provided parameter does not need to be changed, the process continues to block 1030.
[0121] At block 1020, the UE may enable the handover restraining criterion. At block 1022, the UE may determine the UE-configured parameter for the handover restraining criterion. For example, the UE may determine a second signal measurement offset (such as override_A3_offset) that will be used for the handover restraining criterion. The second signal measurement offset may be used to override the first signal measurement offset in the reporting criterion. The resulting modified reporting criterion may be referred to as the handover restraining criterion. From block 1022, the process continues to block 1040.
[0122] Alternatively, if the UE had determined that the network-provided parameter does not need to be changed at block 1016 (for example, when there are no recent handover events or when the sum of the A3_offset and hysteresis margin is less than the override threshold value, among other examples) the process continues to block 1030. At block 1030, the UE may disable the handover restraining criterion. At block 1032, the UE may use the network-provided parameter (such as A3_offset) and reporting criterion without the handover restraining criterion. [0123] At block 1040, the UE may perform signal measurements and prepare for an event evaluation operation to detect an occurrence of the measurement reporting event. In initiating the event evaluation operation, the UE may monitor the signal measurement of the BS and neighbor cells over time. At block 1050, the UE may evaluate the signal measurements based on the network-provided parameter (if the handover restraining criterion is disabled) or the UE- configured parameter (if the handover restraining criterion is disabled). In some implementations, the UE may select whether to use the network-provided parameter or the UE- configured parameter based on a signal measurement of the serving cell, as described further with reference to Figure 10B).
[0124] At block 1080, the UE may determine whether a measurement reporting event is triggered based on the evaluation in block 1050. If the UE detects an occurrence of a measurement reporting event based on a comparison of the signal measurements between the BS and the one or more neighbor cells, the process continues to block 1090. If the UE does not detect an occurrence of the measurement reporting event, the process may return to block 1040 to periodically perform new signal measurements. Alternatively, or additionally, the process may return to block 1016 if the network-provided parameter is changed by a new measurement configuration following a handover or if the frequency of handovers changes.
[0125] At block 1090, the UE communicates a triggered measurement report that includes indication of the occurrence of the measurement reporting event. The triggered measurement report may initiate a handover of the UE between the BS and the one or more neighbor cells. [0126] Figure 10B is a flow diagram of an example process 1002 of a measurement evaluation. A UE may perform a measurement evaluation periodically while monitoring the signal measurements. The example process 1002 may correspond to block 1050 described with reference to Figure 10A. As part the measurement evaluation, the UE may determine whether the first signal measurement offset (A3_offset) is overridden by the second signal measurement offset (override_A3_offset). Furthermore, the UE may determine which signal measurement offset to use based on a current signal measurement of the current serving cell. Thus, the UE can streamline the measurement evaluation while adapting quickly to changed channel conditions. [0127] At block 1052, the UE may obtain signal measurements of the serving cell and one or more neighbor cells. At block 1056, the UE may determine whether the handover restraining criterion is enabled. If the UE determines that the handover restraining criterion is currently enabled, the process 1002 proceeds to block 1060. Otherwise, the process 1002 proceeds to block 1070.
[0128] At block 1060, the UE may determine whether the signal measurement (such as, RSRP value) of the current serving cell is less than the second signal strength threshold (such as, RSRP Low Threshold). If the UE determines that the RSRP value of the serving cell is less than the RSRP Low Threshold, the process 1002 proceeds to block 1062. Otherwise, the process 1002 proceeds to block 1066.
[0129] At block 1062, the UE may disable the handover restraining criterion because the RSRP value of the serving cell is less than the RSRP Low Threshold. At block 1064, the UE may use the first signal measurement offset (such as A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the reporting criterion. The first signal measurement offset may be the network-provided parameter originally obtained from the measurement configuration. The UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
[0130] At block 1066, the UE may use the second signal measurement offset (such as override_A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the handover restraining criterion. The UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
[0131] From block 1056, when the UE determines that the handover restraining criterion is not currently enabled, the process 1002 proceeds to block 1070. At block 1070, the UE determines whether the RSRP value of the current serving cell is greater than the first signal strength threshold (such as, RSRP High Threshold). If the UE determines that the RSRP value is greater than the RSRP High Threshold, the process 1002 proceeds to block 1072. Otherwise, the process 1002 proceeds to block 1076. [0132] At block 1072, the UE may enable the handover restraining criterion because the RSRP value of the serving cell is greater than the RSRP High Threshold. At block 1074, the UE may use the second signal measurement offset (such as override_A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the handover restraining criterion. The second signal measurement offset may be a UE-configured parameter that is different from the network-provided parameter originally obtained from the measurement configuration. The UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset. [0133] At block 1076, the UE may use the first signal measurement offset (such as A3_offset) to determine whether the signal measurements of the neighbor cell satisfy the reporting criterion. The first signal measurement offset may be the network-provided parameter originally obtained from the measurement configuration. The UE may detect the occurrence of the measurement reporting event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
[0134] Figure 11 shows example measurement reporting events 1100 based on combinations of their respective reporting criterion and a handover restraining criterion. The example measurement reporting events 1100 include a modified Event A3 1110, a modified Event A4 1140, and a modified Event A5 1170. For visual distinction, each of the example measurement reporting events 1100 is shown in association with their reporting criterion on the left side of the Figure 11 and an example handover restraining criterion on the right side of the Figure 11.
[0135] The Event A3 and its reporting criterion was described with reference to Figure 4.
The reporting criterion 1120 for Event A3 is traditionally triggered when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) by an offset amount over the SpCell. In some implementations, the modified Event A3 1110 may be triggered based on a combination of the reporting criterion 1120 and a handover restraining criterion, such as the example handover restraining criterion 1130. The example handover restraining criterion 1130 is satisfied when the neighbor signal quality (such as SNR) becomes higher than the signal quality of the SpCell by an offset amount for a time window T. Inequality (1) may be used to determine when the reporting criterion 1120 is satisfied and inequality (2) may be used to determine when the example handover restraining criterion 1130 is satisfied. Inequality (1) is restated below in relation to an inequality (2) for the example handover restraining criterion 1130.
Mn + Ofin + Ofin - Hys > Mp + Ofp + Ocp +Off (for duration of timeToTrigger) (1) SNR of Mn > SNR of Mp + ThresholdSNR (for time window T) (2)
The ThresholdSNR may be a configurable parameter, such as 2-3 dBs. Inequality (2) is satisfied when the SNR of the neighbor cell is higher by at least ThresholdSNR over the SNR of the SpCell.
[0136] Event A4 is traditionally triggered when a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a threshold. Thus, the reporting criterion 1150 for Event A4 is satisfied when a neighbor cell becomes stronger or higher a threshold ( Thresh ) value and an offset amount that is set in the measurement configuration. Inequality (3) may be used to determine when the reporting criterion 1150 for the Event A4 triggered report 1140 is satisfied. The Thresh value is in the same unit as the Mn. so the unit will be dBm in case of RSRP or dB in case of RSRQ and RS-SINR. The other variables, Mn , Ofn. Ocp, and Hys. are the same as described with reference to Event A3. In some implementations, the modified Event A4 1140 may be triggered based on a combination of the reporting criterion 1150 and a handover restraining criterion, such as the example handover restraining criterion 1160. The example handover restraining criterion 1160 is satisfied when the neighbor signal quality (such as SNR) becomes higher than a threshold and an offset amount for a time window T. Inequality (3) may be used to determine when the reporting criterion 1150 is satisfied and inequality (4) may be used to determine when the example handover restraining criterion 1160 is satisfied.
Mn + Ofn + Ocn - Hys > Thresh (for duration of timeToTrigger) (3)
SNR of Mn > ThresholdSNR (for time window T) (4)
As before, the ThresholdSNR may be a configurable parameter, such as 2-3 dBs.
[0137] Event A5 is traditionally triggered when the SpCell becomes worse than a first threshold ( Threshl ) and a neighbor cell becomes better (such as stronger signal strength or higher signal quality) than a second threshold (Threshl). Inequality (5) and Inequality (6) may be used to determine when the reporting criterion 1170 for the Event A5 is satisfied. Threshl and Thresh2 are parameters provided by the base station in the measurement configuration. The other variables, Mp, Hys, Mn, Ofn, Ocn, and Hys, are the same as described with reference to Event A3. In some implementations, the modified Event A5 1170 may be triggered based on a combination of the reporting criterion 1170 and a handover restraining criterion, such as the example handover restraining criterion 1190. The example handover restraining criterion 1190 is satisfied when the neighbor signal quality (such as SNR) becomes higher than the signal quality of the SpCell by an offset amount for a time window T. Inequality (5) and inequality (6) may be used to determine when the reporting criterion 1170 is satisfied and inequality (7) may be used to determine when the example handover restraining criterion 1190 is satisfied.
Mp + Hys < Threshl (for duration of timeToTrigger) (5) Mn + Ofn + Ocn - Hys > Thresh2 (for duration of timeToTrigger) (6)
SNR of Mn > SNR of Mp + ThresholdSNR (for time window T) (7)
[0138] The modified Events described in Figure 7 may enable a UE to mitigate excessive handovers by adding a handover restraining criterion before sending a triggered measurement report that would otherwise by triggered by just the reporting criterion. Some other techniques for mitigating excessive handovers may be based on a network-provided cell blacklist or cell whitelist.
[0139] Figure 12 shows a flowchart illustrating an example process 1200 to mitigate excessive handovers using a network-provided cell blacklist. The network-provided cell blacklist may be provided by a base station that provides the SpCell of either the MCG or SCG. The example operations of process 1200 may be implemented by a base station or its components as described herein. For example, the process 1200 may be performed by an apparatus such as an eNB or gNB described herein or a wireless communication device such as the wireless communication device 1400 described with reference to Figure 14.
[0140] At block 1210, the apparatus may establish a connection with a user equipment (UE) via a serving cell of the first base station.
[0141] At block 1220, the apparatus may prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold.
[0142] At block 1230, the apparatus may transmit a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0143] Using Event A3 as an example, the traditional measurement configuration for a traditional Event A3 may include the following parameters: eventA3 SEQUENCE { a3-Offset MeasTriggerQuantityOffset, reportOnLeave BOOLEAN, hysteresis, timeToTrigger, useWhiteCellList BOOLEAN
}
[0144] The a3-Offset parameter is the offset value(s) (such as Off) to be used in NR measurement report triggering condition for event. A typical value for the a3-Offset parameter may be 2 dB. The reportOnLeave parameter indicates whether the event is triggered when the reporting criteria was satisfied and when the reporting criteria is no longer satisfied. The examples of this disclosure are based on entering an event, so the reportOnLeave may be set to false. The hysteresis parameter indicates the Hys variable for inequality (1). The timeToTrigger parameter indicates the duration of the timeToTrigger. The reporting criterion may be satisfied if the inequality (1) is true for a duration of the timeToTrigger. A typical value for the timeToTrigger parameter may be 320 milliseconds. The useWhiteCellList parameter indicates whether only the cells included in the white-list of the associated neighbor cell are to be measured for the event. A typical value for this parameter is false.
[0145] The measurement configuration does not currently include a parameter to indicate a cell blacklist. However, in some implementations, the measurement configuration may be modified to include a cell blacklist that applies to the Event A3. Similarly, the measurement configuration for Event A4 or Event A5 may be modified to include a cell blacklist.
[0146] The apparatus may determine which cells to include in the cell blacklist based on the history of handover events between particular cells that share partially overlapping coverage. In some implementations, the apparatus may use machine learning or pattern matching to identify cells which create undesirable excessive handover events. In some implementations, the cell blacklist may be based on an architecture or deployment map associated with the base stations in a geographic area.
[0147] A UE that receives a measurement configuration that includes the cell blacklist may only send triggered measurement reports for neighbor cells that are not indicted in the cell blacklist.
[0148] Figure 13 shows a conceptual diagram of an example configuration message 1300. The configuration message 1300 may include a frame header 1324 and a payload 1310. The frame header 1324 may indicate the type of message or other frame control information. The payload 1310 may include a variety of elements or fields 1332. Figure 10 includes several example elements or fields 1360.
[0149] In some implementations, the example elements or fields 1360 may include a measurement configuration 1362. The measurement configuration 1362 may indicate, among other things, which triggered measurement reports are configured, measurement objects (regarding neighbor cells), and the like. The example elements or fields 1360 may include reporting criteria parameters 1364 for each configured reporting event. In some implementations, the example elements or fields 1360 may include a neighbor cell whitelist 1366, a neighbor cell blacklist 1367, or both. The reporting criteria parameters 1364, the neighbor cell whitelist 1366, and the neighbor cell blacklist 1367 may be formatted as subfields within the measurement configuration 1362 or may be included as separate fields in the configuration message 1300.
[0150] Other types of elements, fields, or indicators may be conceivable to include in the example configuration message 1300 to configure the UE with a measurement configuration such as those described herein. In some implementations, the example message 1300 may be part of an RRC Connection Reconfiguration message.
[0151] Figure 14 shows a block diagram of an example wireless communication device 1400. In some implementations, the wireless communication device 1400 can be an example of a device for use in a UE, such as UE 120 described above with reference to Figure 1. The wireless communication device 1400 is capable of transmitting (or outputting for transmission) and receiving wireless communications.
[0152] The wireless communication device 1400 can be, or can include, a chip, system on chip (SoC), chipset, package or device. The term “system-on-chip” (SoC) is used herein to refer to a set of interconnected electronic circuits typically, but not exclusively, including one or more processors, a memory, and a communication interface. The SoC may include a variety of different types of processors and processor cores, such as a general purpose processor, a central processing unit (CPU), a digital signal processor (DSP), a graphics processing unit (GPU), an accelerated processing unit (APU), a sub-system processor, an auxiliary processor, a single-core processor, and a multicore processor. The SoC may further include other hardware and hardware combinations, such as a field programmable gate array (FPGA), a configuration and status register (CSR), an application-specific integrated circuit (ASIC), other programmable logic device, discrete gate logic, transistor logic, registers, performance monitoring hardware, watchdog hardware, counters, and time references. SoCs may be integrated circuits (ICs) configured such that the components of the IC reside on the same substrate, such as a single piece of semiconductor material (such as, for example, silicon).
[0153] The term “system in a package” (SIP) is used herein to refer to a single module or package that may contain multiple resources, computational units, cores or processors on two or more IC chips, substrates, or SoCs. For example, a SIP may include a single substrate on which multiple IC chips or semiconductor dies are stacked in a vertical configuration. Similarly, the SIP may include one or more multi-chip modules (MCMs) on which multiple ICs or semiconductor dies are packaged into a unifying substrate. A SIP also may include multiple independent SoCs coupled together via high speed communication circuitry and packaged in close proximity, such as on a single motherboard or in a single mobile communication device. The proximity of the SoCs facilitates high speed communications and the sharing of memory and resources. [0154] The term “multicore processor” is used herein to refer to a single IC chip or chip package that contains two or more independent processing cores (for example a CPU core, IP core, GPU core, among other examples) configured to read and execute program instructions.
An SoC may include multiple multicore processors, and each processor in an SoC may be referred to as a core. The term “multiprocessor” may be used herein to refer to a system or device that includes two or more processing units configured to read and execute program instructions.
[0155] The wireless communication device 1400 may include one or more modems 1402. In some implementations, the one or more modems 1402 (collectively “the modem 1402”) may include a WWAN modem (for example, a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device 1400 also includes one or more radios 1404 (collectively “the radio 1404”). In some implementations, the wireless communication device 1400 further includes one or more processors, processing blocks or processing elements 1406 (collectively “the processor 1406”) and one or more memory blocks or elements 1407 (collectively “the memory 1407”).
[0156] The modem 1402 can include an intelligent hardware block or device such as, for example, an application-specific integrated circuit (ASIC) among other possibilities. The modem 1402 is generally configured to implement a PHY layer. For example, the modem 1402 is configured to modulate packets and to output the modulated packets to the radio 1404 for transmission over the wireless medium. The modem 1402 is similarly configured to obtain modulated packets received by the radio 1404 and to demodulate the packets to provide demodulated packets. In addition to a modulator and a demodulator, the modem 1402 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), a coder, a decoder, a multiplexer and a demultiplexer. For example, while in a transmission mode, data obtained from the processor 1406 is provided to a coder, which encodes the data to provide encoded bits. The encoded bits are mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols. The modulated symbols may be mapped to a number NSS of spatial streams or a number NSTS of space-time streams. The modulated symbols in the respective spatial or space-time streams may be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and subsequently provided to the DSP circuitry for Tx windowing and filtering. The digital signals may be provided to a digital-to-analog converter (DAC). The resultant analog signals may be provided to a frequency upconverter, and ultimately, the radio 1404. In implementations involving beamforming, the modulated symbols in the respective spatial streams are precoded via a steering matrix prior to their provision to the IFFT block. [0157] While in a reception mode, digital signals received from the radio 1404 are provided to the DSP circuitry, which is configured to acquire a received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offsets. The DSP circuitry is further configured to digitally condition the digital signals, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting for I/Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuitry may be fed to the AGC, which is configured to use information extracted from the digital signals, for example, in one or more received training fields, to determine an appropriate gain. The output of the DSP circuitry also is coupled with the demodulator, which is configured to extract modulated symbols from the signal and, for example, compute the logarithm likelihood ratios (LLRs) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled with the decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all of the spatial streams are fed to the demultiplexer for demultiplexing. The demultiplexed bits may be descrambled and provided to the MAC layer (the processor 1406) for processing, evaluation, or interpretation.
[0158] The radio 1404 generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) and at least one RF receiver (or “receiver chain”), which may be combined into one or more transceivers. For example, the RF transmitters and receivers may include various DSP circuitry including at least one power amplifier (PA) and at least one low-noise amplifier (LNA), respectively. The RF transmitters and receivers may, in turn, be coupled to one or more antennas. For example, in some implementations, the wireless communication device 1400 can include, or be coupled with, multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem 1402 are provided to the radio 1404, which transmits the symbols via the coupled antennas. Similarly, symbols received via the antennas are obtained by the radio 1404, which provides the symbols to the modem 1402.
[0159] The processor 1406 can include an intelligent hardware block or device such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD) such as a field programmable gate array (FPGA), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor 1406 processes information received through the radio 1404 and the modem 1402, and processes information to be output through the modem 1402 and the radio 1404 for transmission through the wireless medium. In some implementations, the processor 1406 may generally control the modem 1402 to cause the modem to perform various operations described above.
[0160] The memory 1407 can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof. The memory 1407 also can store non-transitory processor- or computer-executable software (SW) code containing instructions that, when executed by the processor 1406, cause the processor to perform various operations described herein for wireless communication, including the generation, transmission, reception and interpretation of MPDUs, frames or packets. For example, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein, can be implemented as one or more modules of one or more computer programs.
[0161] Figures 1-14 and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently.
[0162] The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects. While the aspects of the disclosure have been described in terms of various examples, any combination of aspects from any of the examples is also within the scope of the disclosure. The examples in this disclosure are provided for pedagogical purposes. Alternatively, or in addition to the other examples described herein, examples include any combination of the following implementation options (enumerated as clauses for clarity).
CLAUSES
[0163] 1. A method for wireless communication performed by an apparatus of a user equipment (UE), including: establishing at least a first connection with a serving cell of a base station (BS); receiving a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell, where the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; monitoring for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters; and communicating the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
[0164] Clause 2. The method of clause 1, further including: obtaining signal measurements of a plurality of reference signals from the BS and one or more neighbor cells; determining that the reporting criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the one or more network-provided parameters; determining that the handover restraining criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the UE-configured parameter; and detecting the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
[0165] Clause 3. The method of any one of clauses 1-2, further including refraining from communicating the triggered measurement report when the handover restraining criterion is not satisfied regardless of whether the reporting criterion is satisfied.
[0166] Clause 4. The method of any one of clauses 1-3, where the one or more network- provided parameters includes a first signal measurement offset to adjust a measurement result of the serving cell before evaluating the reporting criterion, and where the UE-configured parameter includes a second signal measurement offset that is greater than the first signal measurement offset such that the measurement result of the serving cell is adjusted to a greater value before evaluating the handover restraining criterion.
[0167] Clause 5. The method of clause 4, further including: determining the second signal measurement offset based on the first signal measurement offset and an adjustment value, where the adjustment value is based on a quantity of handover events during a preceding time period, a time since a previous handover event, a movement speed of the UE, or any combination thereof. [0168] Clause 6. The method of any one of clauses 1-5, further including: determining a quantity of handover events during a preceding time period; determining a frequency of handovers based on the quantity of handover events during the preceding time period; and adjusting the UE-configured parameter of the handover restraining criterion based on the frequency of handovers.
[0169] Clause 7. The method of any one of clauses 1-6, where the handover restraining criterion cannot be satisfied until expiration of a delay timer initiated after a previous handover event, the method further including: setting a duration of the delay timer based on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiating the delay timer after the previous handover event. [0170] Clause 8. The method of clause 7, where setting the duration of the delay timer includes: determining a frequency of handovers based on the quantity of handover events during the preceding time period; setting the duration to a first value when the frequency of handovers is below a handover frequency threshold; and setting the duration to a second value when the frequency of handovers is above the handover frequency threshold, the second value higher than the first value.
[0171] Clause 9. The method of clause 7, where setting the duration of the delay timer includes: setting the duration to a first value when the UE stationary; setting the duration to a second value when the UE is non-stationary and the movement speed of the UE is lower than a speed threshold, the second value lower than the first value; and setting the duration to a third value when the UE is non-stationary and the movement speed of the UE is higher than the speed threshold, the third value lower than the second value.
[0172] Clause 10. The method of any one of clauses 7-9, further including: determining whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disabling the delay timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
[0173] Clause 11. The method of any one of clauses 1-10, where the UE-configured parameter limits the occurrence of the measurement reporting event such that the UE is prevented from ping-pong handovers between the serving cell and the neighbor cell.
[0174] Clause 12. The method of any one of clauses 1-11, further including: enabling the handover restraining criterion when the handover restraining criterion is disabled and a signal measurement of the serving cell is greater than a first signal strength threshold (RSRP High Threshold); and disabling the handover restraining criterion when the handover restraining criterion is enabled and the signal measurement of the serving cell is less than a second signal strength threshold (RSRP Low Threshold).
[0175] Clause 13. The method of any one of clauses 1-12, where the measurement reporting event is an A3 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a corresponding signal measurement of the serving cell plus a first signal measurement offset (A3_offset), the A3_offset being one of the one or more network-provided parameters; and where the handover restraining criterion is satisfied when the signal measurement of the neighbor cell is higher than the corresponding signal measurement of the serving cell plus a second signal measurement offset (override_A3_offset), the override_A3_offset being the UE-configured parameter. [0176] Clause 14. The method of clause 13, further including: determining that the A3_offset plus a hysteresis margin is less than an override threshold value; and generating the override_A3_offset based on the override threshold value minus the hysteresis margin.
[0177] Clause 15. The method of any one of clauses 1-14, where the measurement reporting event is an A3 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a corresponding signal measurement of the serving cell plus a network-provided offset, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
[0178] Clause 16. The method of any one of clauses 1-15, where the measurement reporting event is an A4 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a network-provided threshold, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
[0179] Clause 17. The method of any one of clauses 1-16, where the measurement reporting event is an A5 event specified in a technical standard and the reporting criterion includes a current signal measurement of the first connection being below a first signal strength threshold and the signal measurement of the neighbor cell being greater than a second signal strength threshold, and where the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
[0180] Clause 18. The method of any one of clauses 1-17, where the handover restraining criterion includes one or more criterion selected from a group consisting of: an expiration of a delay timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
[0181] Clause 19. The method of any one of clauses 1-18, where the measurement configuration includes a cell blacklist associated with the triggered measurement report, the method further including: determining whether the neighbor cell is in the cell blacklist; and communicating the triggered measurement report when both the reporting criterion and the handover restraining criterion are satisfied and the neighbor cell is not included in the cell blacklist. [0182] Clause 20. The method of any one of clauses 1-19, where establishing at least the first connection includes: establishing the first connection with the serving cell of the BS in a Long-Term Evolution (LTE) radio access network (RAN), the serving cell being designated as a primary serving cell; and establishing a second connection with a secondary serving cell of another BS in a 5G New Radio (NR) RAN.
[0183] Clause 21. A method for wireless communication performed by a first base station, including: establishing a connection with a user equipment (UE) via a serving cell of the first base station; preparing a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and transmitting a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0184] Clause 22. The method of clause 21, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
[0185] Clause 23. The method of any one of clauses 21-22, where preparing the cell blacklist includes: determining a frequency of handover events associated with the neighbor cell based on the quantity of handover events over a time period; and including the neighbor cell in the cell blacklist if the frequency of handover events is above a threshold.
[0186] Clause 24. The method of any one of clauses 21-23, where preparing the cell blacklist includes: determining that the neighbor cell provides an overlapping geographic coverage area with the serving cell; determining that the UE is in a location of the overlapping geographic coverage area and that the quantity of handover events for the UE is higher than an average quantity of handover events for other UEs in other locations of the overlapping geographic coverage area; and including the neighbor cell in the cell blacklist for the UE.
[0187] Clause 25. A user equipment (UE), including: at least one modem configured to: establish at least a first connection with a serving cell of a base station (BS), and obtain a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based on one or more network-provided parameters and a signal measurement of a neighbor cell, where the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; a processing system configured to monitor for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based on a UE-configured parameter different from the one or more network-provided parameters; and the at least one modem configured to communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
[0188] Clause 26. The UE of clause 25, where the processing system is further configured to: determine a quantity of handover events during a preceding time period; determine a frequency of handovers based on the quantity of handover events during the preceding time period; and adjust the UE-configured parameter of the handover restraining criterion based on the frequency of handovers.
[0189] Clause 27. The UE of any one of clauses 25-26, where the processing system is further configured to: set a duration of a delay timer based on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiate the delay timer after a previous handover event, where the handover restraining criterion cannot be satisfied until expiration of the delay timer initiated after the previous handover event. [0190] Clause 28. The UE of any one of clauses 25-27, further including: at least one transceiver coupled to the at least one modem; at least one antenna coupled to the at least one transceiver to wirelessly transmit signals output from the at least one transceiver and to wirelessly receive signals for input into the at least one transceiver; and a housing that encompasses at least the processing system, the at least one modem, the at least one transceiver, and at least a portion of the at least one antenna.
[0191] Clause 29. An apparatus of a first base station, including: a processing system configured to: establish a connection with a user equipment (UE) via a serving cell of the first base station, and prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and at least one modem configured to output a measurement configuration for transmission to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0192] Clause 30. The apparatus of clause 29, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
[0193] Clause 31. A method for wireless communication performed by an apparatus of a user equipment (UE), including: establishing a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; receiving a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and sending the triggered measurement report when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
[0194] Clause 32. The method of clause 31, further including: refraining from sending the triggered measurement report when the handover moderation criterion is not satisfied.
[0195] Clause 33. The method of any one of clauses 31-32, where the handover moderation criterion includes one or more criterion selected from a group consisting of: an expiration of a hold timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
[0196] Clause 34. The method of clause 33, further including: determining a duration of the hold timer, the signal strength change threshold or the signal quality precondition threshold based on a user-configurable setting, a network-configurable setting or a manufacturer configurable setting.
[0197] Clause 35. The method of any one of clauses 31-34, further including: determining a quantity of handover events during a preceding time period; determining a frequency of handovers based on the quantity of handover events during the preceding time period; and adjusting the handover moderation criterion based on the frequency of handovers.
[0198] Clause 36. The method of clause 35, where the handover moderation criterion is based on a hold timer, and where adjusting the handover moderation criterion includes: setting a duration of the hold timer based on the frequency of handovers; initiating the hold timer after a previous handover; and determining that the handover moderation criterion is satisfied when the hold timer expires.
[0199] Clause 37. The method of clause 36, where setting the duration of the hold timer includes: setting the duration to a first value when the frequency of handovers is above a first level; and setting the duration to a second value when the frequency of handovers is below the first level, the first value higher than the second value.
[0200] Clause 38. The method of clause 36, where setting the duration of the hold timer includes: determining that the handover frequency is within a first range from among a plurality of ranges, where each range of the plurality of ranges is associated with a different duration value; and setting the duration of the hold timer based on a duration value of the first range. [0201] Clause 39. The method of clause 36, further including: determining whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disabling the hold timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
[0202] Clause 40. The method of clause 36, further including: determining that the UE is stationary; and evaluating the handover moderation criterion as a precondition to sending the triggered measurement report based on a determination that the UE is stationary.
[0203] Clause 41. The method of any one of clauses 31-40, where the measurement report is an A3 event report and the reporting criterion includes the measurement being greater than a corresponding measurement of the first serving cell or the second serving cell, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
[0204] Clause 42. The method of any one of clauses 31-41, where the measurement report is an A4 event report and the reporting criterion includes the measurement being greater than a signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
[0205] Clause 43. The method of any one of clauses 31-42, where the measurement report is an A5 event report and the reporting criterion includes a current signal strength of the first connection being below a first signal strength threshold and the measurement of the neighbor cell being greater than a second signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
[0206] Clause 44. The method of any one of clauses 31-43, where the measurement configuration includes a cell blacklist associated with the triggered measurement report, the method further including: determining whether the neighbor cell is in the cell blacklist; and sending the triggered measurement report when both the reporting criterion and the handover moderation criterion are satisfied and the neighbor cell is not included in the cell blacklist.
[0207] Clause 45. A method for wireless communication performed by an apparatus of a first base station, including: establishing a connection with a user equipment (UE) via a first serving cell of the first base station; determining a quantity of handover events where the UE’s connection with the first serving cell is handed over to a neighbor cell of the first base station or a second base station; preparing a cell blacklist that includes the neighbor cell based on a determination that the quantity of handover events is above a threshold; and transmitting the measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
[0208] Clause 46. The method of clause 45, where the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the measurement report for the one or more cells included in the cell blacklist.
[0209] Clause 47. The method of any one of clauses 45-46, where preparing the cell blacklist includes: determining a frequency of handover events associated with the neighbor cell based on the quantity of handover events over a time period; and including the neighbor cell in the cell blacklist if the frequency of handover events is above a threshold.
[0210] Clause 48. The method of any one of clauses 45-47, where preparing the cell blacklist includes: determining that the neighbor cell provides an overlapping geographic coverage area with the first serving cell or the second serving cell; determining that the UE is in a location of the overlapping geographic coverage area and that the quantity of handover events for the UE is higher than an average quantity of handover events for other UEs in other locations of the overlapping geographic coverage area; and including the neighbor cell in the cell blacklist for the UE.
[0211] Clause 49. A user equipment (UE) for wireless communication, including: one or more processors configured to: establish a first connection with a first serving cell of a Long- Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; an interface configured to: obtain a measurement configuration including a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
[0212] Clause 50. The UE of clause 49, further including: the one or more processors configured to cause the interface to refrain from outputting the triggered measurement report when the handover moderation criterion is not satisfied.
[0213] Clause 51. The UE of any one of clauses 49-50, where the handover moderation criterion includes one or more criterion selected from a group consisting of: an expiration of a hold timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
[0214] Clause 52. The UE of clause 51, further including: the one or more processors configured to determine a duration of the hold timer, the signal strength change threshold or the signal quality precondition threshold based on a user-configurable setting, a network- configurable setting or a manufacturer configurable setting.
[0215] Clause 53. The UE of any one of clauses 49-52, where the one or more processors are further configured to: determine a quantity of handover events during a preceding time period; determine a frequency of handovers based on the quantity of handover events during the preceding time period; and adjust the handover moderation criterion based on the frequency of handovers.
[0216] Clause 54. The UE of clause 53, where the handover moderation criterion is based on a hold timer, and where the one or more processors are further configured to: set a duration of the hold timer based on the frequency of handovers; initiate the hold timer after a previous handover; and determine that the handover moderation criterion is satisfied when the hold timer expires.
[0217] Clause 55. The UE of clause 54, where the one or more processors are further configured to: set the duration to a first value when the frequency of handovers is above a first level; and set the duration to a second value when the frequency of handovers is below the first level, the first value higher than the second value.
[0218] Clause 56. The UE of clause 54, where the one or more processors are further configured to: determine that the handover frequency is within a first range from among a plurality of ranges, where each range of the plurality of ranges is associated with a different duration value; and set the duration of the hold timer based on a duration value of the first range. [0219] Clause 57. The UE of clause 54, where the one or more processors are further configured to: determine whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disable the hold timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
[0220] Clause 58. The UE of clause 54, where the one or more processors are further configured to determine whether the UE is stationary or nonstationary, and evaluate the handover moderation criterion as a precondition to sending the triggered measurement report based on a determination that the UE is stationary. [0221] Clause 59. The UE of any one of clauses 49-58, where the measurement report is an A3 event report and the reporting criterion includes the measurement being greater than a corresponding measurement of the first serving cell or the second serving cell, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
[0222] Clause 60. The UE of any one of clauses 49-59, where the measurement report is an A4 event report and the reporting criterion includes the measurement being greater than a signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
[0223] Clause 61. The UE of any one of clauses 49-60, where the measurement report is an A5 event report and the reporting criterion includes a current signal strength of the first connection being below a first signal strength threshold and the measurement of the neighbor cell being greater than a second signal strength threshold, and where the handover moderation criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first serving cell or the second serving cell by at least a threshold amount for a time period.
[0224] Clause 62. The UE of any one of clauses 49-61, where the measurement configuration includes a cell blacklist associated with the triggered measurement report, and where the one or more processor is further configured to: determine whether the neighbor cell is in the cell blacklist; cause the interface to output the triggered measurement report when both the reporting criterion and the handover moderation criterion are satisfied and the neighbor cell is not included in the cell blacklist.
[0225] Clause 63. A wireless communication device including: at least one modem; at least one processor communicatively coupled with the at least one modem; and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
[0226] Clause 64. A portable electronic device including: a wireless communication device including: at least one modem; at least one processor communicatively coupled with the at least one modem; and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report; a plurality of antennas coupled to the at least one transceiver to wirelessly transmit signals output from the at least one transceiver; and a housing that encompasses the at least one modem, the at least one processor, the at least one memory, the at least one transceiver and at least a portion of the plurality of antennas.
[0227] Clause 65. A machine-readable medium having processor-readable instructions stored therein that, when executed by at least one processor of a user equipment (UE), cause the UE: establish at least a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5GNew Radio (NR) RAN; obtain a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and output the triggered measurement report for transmission when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report.
[0228] Clause 66. A system for use in a user equipment (UE), including: means for establishing a first connection with a first serving cell of a Long-Term Evolution (LTE) radio access network (RAN) and a second connection with a second serving cell of a 5G New Radio (NR) RAN; means for receiving a measurement configuration that includes a reporting criterion for a triggered measurement report based on a measurement of a neighbor cell of the LTE RAN or the NR RAN; and means for sending the triggered measurement report when both the reporting criterion and a handover moderation criterion are satisfied, the handover moderation criterion being different from the reporting criterion for the triggered measurement report. [0229] Clause 67. A method of wireless communication performed by a user equipment (UE), including: obtaining signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; detecting an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and communicating, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
[0230] Clause 68. The method of clause 67, further including: receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the receiving the measurement configuration includes receiving the measurement configuration in one or more BCCHs of the plurality of BCCHs.
[0231] Clause 69. The method of any one of clauses 67-68, further including: receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the receiving the measurement configuration includes receiving the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
[0232] Clause 70. The method of any one of clauses 67-69, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the communicating the measurement report includes transmitting, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
[0233] Clause 71. The method of any one of clauses 67-70, further including: receiving a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the receiving the measurement configuration includes receiving the measurement configuration in a radio resource control (RRC) message.
[0234] Clause 72. The method of clause 71, further including: modifying the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset. [0235] Clause 73. The method of clause 71, where the obtaining the signal measurements includes: obtaining a plurality of predetermined parameters from the measurement configuration; determining whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generating the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
[0236] Clause 74. The method of clause 73, where the generating the second signal measurement offset includes: determining whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generating the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
[0237] Clause 75. The method of clause 74, further including: retaining the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
[0238] Clause 76. The method of clause 74, further including: initiating an event evaluation operation to detect an occurrence of the specified measurement event; determining whether the first signal measurement offset is overridden by the second signal measurement offset; determining whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and determining whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
[0239] Clause 77. The method of clause 76, where the detecting the occurrence of the specified measurement event includes: applying the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset. [0240] Clause 78. The method of clause 76, where the detecting the occurrence of the specified measurement event includes: applying the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
[0241] Clause 79. The method of clause 76, where the initiating the event evaluation operation includes: monitoring the signal measurement of the BS over time; comparing the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and comparing the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
[0242] Clause 80. The method of any one of clauses 67-79, further including: measuring a plurality of transmission beams associated with the BS during a first time period; and obtaining a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
[0243] Clause 81. The method of clause 80, further including: receiving, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
[0244] Clause 82. The method of clause 81, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the receiving the request includes receiving the request in one or more PDCCHs of the plurality of PDCCHs.
[0245] Clause 83. The method of clause 81, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0246] Clause 84. The method of clause 81, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0247] Clause 85. The method of any one of clauses 67-84, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
[0248] Clause 86. The method of clause 85, where the downlink specific reference signal includes a synchronization signal block (SSB).
[0249] Clause 87. The method of clause 85, where the downlink specific reference signal includes a channel state information reference signal (CSI-RS).
[0250] Clause 88. The method of clause 88, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
[0251] Clause 89. The method of clause 88, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
[0252] Clause 90. The method of any one of clauses 67-89, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
[0253] Clause 91. The method of clause 90, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
[0254] Clause 92. A user equipment (UE) including: a processor configured to: obtain signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; detect an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and a transceiver configured to: communicate, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
[0255] Clause 93. The UE of clause 92, where the transceiver is further configured to: receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
[0256] Clause 94. The UE of any one of clauses 92-93, where the transceiver is further configured to: receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
[0257] Clause 95. The UE of any one of clauses 92-94, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the transceiver configured to communicate the measurement report is further configured to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
[0258] Clause 96. The UE of any one of clauses 92-95, where the transceiver is further configured to: receive a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the transceiver configured to receive the measurement configuration is further configured to receive the measurement configuration in a radio resource control (RRC) message.
[0259] Clause 97. The UE of clause 96, where the processor is further configured to: modify the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
[0260] Clause 98. The UE of clause 96, where the processor configured to obtain the signal measurements is further configured to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active. [0261] Clause 99. The UE of clause 98, where the processor configured to generate the second signal measurement offset is further configured to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
[0262] Clause 100. The UE of clause 99, where the processor is further configured to: retain the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
[0263] Clause 101. The UE of clause 99, where the processor is further configured to: initiate an event evaluation operation to detect an occurrence of the specified measurement event; determine whether the first signal measurement offset is overridden by the second signal measurement offset; determine whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and determine whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
[0264] Clause 102. The UE of clause 101, where the processor configured to detect the occurrence of the specified measurement event is further configured to: apply the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset.
[0265] Clause 103. The UE of clause 101, where the processor configured to detect the occurrence of the specified measurement event is further configured to: apply the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
[0266] Clause 104. The UE of clause 101, where the processor configured to initiate the event evaluation operation is further configured to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
[0267] Clause 105. The UE of any one of clauses 92-104, where the processor is further configured to: measure a plurality of transmission beams associated with the BS during a first time period; and obtain a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
[0268] Clause 106. The UE of clause 105, where the transceiver is further configured to: receive, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
[0269] Clause 107. The UE of clause 106, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the transceiver configured to receive the request is further configured to receive the request in one or more PDCCHs of the plurality of PDCCHs.
[0270] Clause 108. The UE of clause 106, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0271] Clause 109. The UE of clause 106, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0272] Clause 110. The UE of any one of clauses 92-109, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
[0273] Clause 111. The UE of clause 110, where the downlink specific reference signal includes a synchronization signal block (SSB).
[0274] Clause 112. The UE of clause 110, where the downlink specific reference signal includes a channel state information reference signal (CSI-RS).
[0275] Clause 113. The UE of clause 110, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
[0276] Clause 114. The UE of clause 113, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
[0277] Clause 115. The UE of any one of clauses 92-114, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
[0278] Clause 116. The UE of clause 115, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
[0279] Clause 117. A non-transitory computer-readable medium having program code recorded thereon, the program code including: code for causing a user equipment (UE) to obtain signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; code for causing the UE to detect an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and code for causing the UE to communicate, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
[0280] Clause 118. The non-transitory computer-readable medium of clause 117, further including: code for causing the UE to receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
[0281] Clause 119. The non-transitory computer-readable medium of any one of clauses 117-118, further including: code for causing the UE to receive, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs.
[0282] Clause 120. The non-transitory computer-readable medium of any one of clauses 117-119, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the code for causing the UE to communicate the measurement report is further configured to cause the UE to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
[0283] Clause 121. The non-transitory computer-readable medium of any one of clauses 117-120, further including: code for causing the UE to receive a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, the code for causing the UE to receive the measurement configuration is further configured to cause the UE to receive the measurement configuration in a radio resource control (RRC) message.
[0284] Clause 122. The non-transitory computer-readable medium of clause 121, further including: code for causing the UE to modify the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
[0285] Clause 123. The non-transitory computer-readable medium of clause 121, where the code for causing the UE to obtain the signal measurements is further configured to cause the UE to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active. [0286] Clause 124. The non-transitory computer-readable medium of clause 123, where the code for causing the UE to generate the second signal measurement offset is further configured to cause the UE to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
[0287] Clause 125. The non-transitory computer-readable medium of clause 124, further including: code for causing the UE to retain the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
[0288] Clause 126. The non-transitory computer-readable medium of clause 124, further including: code for causing the UE to initiate an event evaluation operation to detect an occurrence of the specified measurement event; code for causing the UE to determine whether the first signal measurement offset is overridden by the second signal measurement offset; code for causing the UE to determine whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and code for causing the UE to determine whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
[0289] Clause 127. The non-transitory computer-readable medium of clause 126, where the code for causing the UE to detect the occurrence of the specified measurement event is further configured to cause the UE to: applying the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detecting the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset. [0290] Clause 128. The non-transitory computer-readable medium of clause 126, where the code for causing the UE to detect the occurrence of the specified measurement event is further configured to cause the UE to: apply the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset. [0291] Clause 129. The non-transitory computer-readable medium of clause 126, where the code for causing the UE to initiate the event evaluation operation is further configured to cause the UE to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
[0292] Clause 130. The non-transitory computer-readable medium of any one of clauses 117-129, further including: code for causing the UE to measure a plurality of transmission beams associated with the BS during a first time period; and code for causing the UE to obtain a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
[0293] Clause 131. The non-transitory computer-readable medium of clause 130, further including: code for causing the UE to receive, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
[0294] Clause 132. The non-transitory computer-readable medium of clause 131, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the code for causing the UE to receive the request is further configured to cause the UE to receive the request in one or more PDCCHs of the plurality of PDCCHs.
[0295] Clause 133. The non-transitory computer-readable medium of clause 131, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0296] Clause 134. The non-transitory computer-readable medium of clause 131, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0297] Clause 135. The non-transitory computer-readable medium of any one of clauses 117-134, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
[0298] Clause 136. The non-transitory computer-readable medium of clause 135, where the downlink specific reference signal includes a synchronization signal block (SSB).
[0299] Clause 137. The non-transitory computer-readable medium of clause 135, where the downlink specific reference signal includes a channel state information reference signal (CSI- RS).
[0300] Clause 138. The non-transitory computer-readable medium of clause 135, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
[0301] Clause 139. The non-transitory computer-readable medium of clause 138, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
[0302] Clause 140. The non-transitory computer-readable medium of any one of clauses 117-139, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
[0303] Clause 141. The non-transitory computer-readable medium of clause 140, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
[0304] Clause 142. A user equipment (UE) including: means for obtaining signal measurements of a plurality of downlink specific reference signals from a base station (BS) and one or more neighbor cells; means for detecting an occurrence of a specified measurement event based on a comparison of the signal measurements between the BS and the one or more neighbor cells using a first signal measurement offset or a second signal measurement offset different from the first signal measurement offset; and means for communicating, with the BS in a first subband of a plurality of subbands, a measurement report including indication of the occurrence of the specified measurement event for initiating a handover of the UE between the BS and the one or more neighbor cells.
[0305] Clause 143. The UE of clause 142, further including: means for receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of broadcast control channels (BCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the means for receiving the measurement configuration is further configured to receive the measurement configuration in one or more BCCHs of the plurality of BCCHs.
[0306] Clause 144. The UE of any one of clauses 142-143, further including: means for receiving, in a second subband of the plurality of subbands, a measurement configuration from the BS, where: the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the means for receiving the measurement configuration is further configured to receive the measurement configuration in one or more PDCCHs of the plurality of PDCCHs. [0307] Clause 145. The UE of any one of clauses 142-144, where: the first subband includes a plurality of physical uplink control channels (PUCCHs) multiplexed in at least one of time or frequency in a first portion of a first time period, and the means for communicating the measurement report is further configured to transmit, to the BS, the measurement report in one or more PUCCHs of the plurality of PUCCHs.
[0308] Clause 146. The UE of any one of clauses 142-145, further including: means for receiving a measurement configuration from the BS, the measurement configuration including the first signal measurement offset and a plurality of predetermined parameters, where the means for receiving the measurement configuration is further configured to receive the measurement configuration in a radio resource control (RRC) message.
[0309] Clause 147. The UE of clause 146, further including: means for modifying the measurement configuration with the second signal measurement offset when the first signal measurement offset is overridden by the second signal measurement offset.
[0310] Clause 148. The UE of clause 146, where the means for obtaining the signal measurements is further configured to: obtain a plurality of predetermined parameters from the measurement configuration; determine whether a first predetermined parameter of the plurality of predetermined parameters indicates that an override operation to override the first signal measurement offset is active; and generate the second signal measurement offset to override the first signal measurement offset with the second signal measurement offset when the first predetermined parameter indicates that the override operation is active.
[0311] Clause 149. The UE of clause 148, where the means for obtaining the signal measurements is further configured to: determine whether a summation of the first signal measurement offset and a predetermined hysteresis margin is lesser than an override offset threshold and whether a signal measurement of the BS is greater than a first signal strength threshold of a plurality of signal strength thresholds; and generate the second signal measurement offset from an override offset value that is decreased by the predetermined hysteresis margin when the summation of the first signal measurement offset and the predetermined hysteresis margin is lesser than the override offset threshold and the signal measurement of the BS is greater than the first signal strength threshold.
[0312] Clause 150. The UE of clause 149, further including: means for retaining the first signal measurement offset independent of overriding the first signal measurement offset with the second signal measurement offset when the summation of the first signal measurement offset and the predetermined hysteresis margin is not lesser than the override offset threshold or the signal measurement of the BS is not greater than the first signal strength threshold.
[0313] Clause 151. The UE of clause 149, further including: means for initiating an event evaluation operation to detect an occurrence of the specified measurement event; means for determining whether the first signal measurement offset is overridden by the second signal measurement offset; means for determining whether the signal measurement of the BS is lesser than a second signal strength threshold of the plurality of signal strength thresholds when the first signal measurement offset is overridden by the second signal measurement offset, where the first signal strength threshold is greater than the second signal strength threshold; and means for determining whether the signal measurement of the BS is greater than the first signal strength threshold when the first signal measurement offset is not overridden by the second signal measurement offset.
[0314] Clause 152. The UE of clause 151, where the means for detecting the occurrence of the specified measurement event is further configured to: apply the first signal measurement offset to the event evaluation operation when the signal measurement of the BS is lesser than the second signal strength threshold or the signal measurement of the BS is lesser than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the first signal measurement offset. [0315] Clause 153. The UE of clause 151, where the means for detecting the occurrence of the specified measurement event is further configured to: apply the second signal measurement offset to the event evaluation operation when the signal measurement of the BS is greater than the second signal strength threshold or the signal measurement of the BS is greater than the first signal strength threshold; and detect the occurrence of the specified measurement event when the event evaluation operation indicates that one or more signal measurements of the one or more neighbor cells exceeds the signal measurement of the BS by at least the second signal measurement offset.
[0316] Clause 154. The UE of clause 151, where the means for initiating the event evaluation operation is further configured to: monitor the signal measurement of the BS over time; compare the signal measurement to the second signal strength threshold at a first time that corresponds to a time when the first signal measurement offset is overridden by the second signal measurement offset; and compare the signal measurement to the first signal strength threshold at a second time that corresponds to a time when the first signal measurement offset is not overridden by the second signal measurement offset.
[0317] Clause 155. The UE of any one of clauses 142-154, further including: means for measuring a plurality of transmission beams associated with the BS during a first time period; and means for obtaining a reference signal received power (RSRP) measurement of a downlink specific reference signal carried in each of the plurality of transmission beams.
[0318] Clause 156. The UE of clause 155, further including: means for receiving, from the BS in a second subband of the plurality of subbands, a request to obtain the signal measurements of the plurality of downlink specific reference signals from the BS and the one or more neighbor cells, where the request indicates a request to detect the specified measurement event from the signal measurements.
[0319] Clause 157. The UE of clause 156, where: the request includes a request for the UE to perform one or more signal measurements at a particular time instance during the first time period, the second subband includes a plurality of physical downlink control channels (PDCCHs) multiplexed in at least one of time or frequency in a first portion of the first time period, the means for receiving the request is further configured to receive the request in one or more PDCCHs of the plurality of PDCCHs.
[0320] Clause 158. The UE of clause 156, where the specified measurement event corresponds to an occurrence of detecting a signal strength of a transmission beam from at least one of the one or more neighbor cells that exceeds a signal strength of a transmission beam from the BS by the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0321] Clause 159. The UE of clause 156, where the specified measurement event corresponds to an occurrence of detecting a difference between a signal strength of a transmission beam from at least one of the one or more neighbor cells and a signal strength of a transmission beam from the BS that exceeds the first signal measurement offset or the second signal measurement offset based at least in part on whether the first signal measurement offset is overridden by the second signal measurement offset.
[0322] Clause 160. The UE of any one of clauses 142-159, where the signal measurements from the BS includes a reference signal received power (RSRP) value for a downlink specific reference signal of the plurality of downlink specific reference signals.
[0323] Clause 161. The UE of clause 160, where the downlink specific reference signal includes a synchronization signal block (SSB).
[0324] Clause 162. The UE of clause 160, where the downlink specific reference signal includes a channel state information reference signal (CSI-RS).
[0325] Clause 163. The UE of clause 160, where the signal measurements from the BS includes a received signal strength indicator (RSSI) value for the downlink specific reference signal.
[0326] Clause 164. The UE of clause 163, where the signal measurements from the BS includes a reference signal received quality (RSRQ) value based on the RSRP value and the RSSI value for the downlink specific reference signal.
[0327] Clause 165. The UE of any one of clauses 142-164, where the first signal measurement offset corresponds to a predetermined A3 offset that is set by a new radio core network.
[0328] Clause 166. The UE of clause 165, where the second signal measurement offset corresponds to a user-configurable A3 offset that is at least in part different from the predetermined A3 offset.
[0329] As used herein, the term “component” is intended to be broadly construed as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software. As used herein, the phrase “based on” is intended to be broadly construed to mean “based at least in part on.”
[0330] Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like.
[0331] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c. [0332] The various illustrative components, logic, logical blocks, modules, circuits, operations and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware or software, including the structures disclosed in this specification and the structural equivalents thereof. The interchangeability of hardware, firmware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware, firmware or software depends upon the particular application and design constraints imposed on the overall system.
[0333] The hardware and data processing apparatus used to implement the various illustrative components, logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes, operations and methods may be performed by circuitry that is specific to a given function.
[0334] As described above, in some aspects implementations of the subject matter described in this specification can be implemented as software. For example, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein can be implemented as one or more modules of one or more computer programs. Such computer programs can include non-transitory processor- or computer- executable instructions encoded on one or more tangible processor- or computer-readable storage media for execution by, or to control the operation of, data processing apparatus including the components of the devices described herein. By way of example, and not limitation, such storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store program code in the form of instructions or data structures. Combinations of the above should also be included within the scope of storage media.
[0335] As used herein, the terms “user equipment”, “wireless communication device”, “mobile communication device”, “communication device”, or “mobile device” refer to any one or all of cellular telephones, smartphones, portable computing devices, personal or mobile multi- media players, laptop computers, tablet computers, smartbooks, Intemet-of-Things (IoT) devices, palm-top computers, wireless electronic mail receivers, multimedia Internet enabled cellular telephones, wireless gaming controllers, display sub-systems, driver assistance systems, vehicle controllers, vehicle system controllers, vehicle communication system, infotainment systems, vehicle telematics systems or subsystems, vehicle display systems or subsystems, vehicle data controllers or routers, and similar electronic devices which include a programmable processor and memory and circuitry configured to perform operations as described herein.
[0336] As used herein, the terms “SIM,” “SIM card,” and “subscriber identification module” are used interchangeably to refer to a memory that may be an integrated circuit or embedded into a removable card, and that stores an International Mobile Subscriber Identity (IMSI), related key, or other information used to identify or authenticate a mobile communication device on a network and enable a communication service with the network. Because the information stored in a SIM enables the mobile communication device to establish a communication link for a particular communication service with a particular network, the term “subscription” is used herein as a shorthand reference to refer to the communication service associated with and enabled by the information stored in a particular SIM as the SIM and the communication network, as well as the services and subscriptions supported by that network, correlate to one another. A SIM used in various examples may contain user account information, an international mobile subscriber identity (IMSI), a set of SIM application toolkit (SAT) commands, and storage space for phone book contacts. A SIM card may further store home identifiers (such as, a System Identification Number (SID)/Network Identification Number (NID) pair, a Home Public Land Mobile Number (HPLMN) code, among other examples) to indicate the SIM card network operator provider. An Integrated Circuit Card Identity (ICCID) SIM serial number may be printed on the SIM card for identification. However, a SIM may be implemented within a portion of memory of the mobile communication device, and thus need not be a separate or removable circuit, chip or card. [0337] Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.
[0338] Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
[0339] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one or more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.

Claims

CLAIMS What is claimed is:
1. A method for wireless communication performed by an apparatus of a user equipment (UE), comprising: establishing at least a first connection with a serving cell of a base station (BS); receiving a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based, at least in part, on one or more network-provided parameters and a signal measurement of a neighbor cell, wherein the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; monitoring for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based, at least in part, on a UE-configured parameter different from the one or more network-provided parameters; and communicating the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
2. The method of claim 1, further comprising: obtaining signal measurements of a plurality of reference signals from the BS and one or more neighbor cells; determining that the reporting criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the one or more network-provided parameters; determining that the handover restraining criterion is satisfied based on a comparison of signal measurements from the BS and those from the one or more neighbor cells using the UE- configured parameter; and detecting the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
3. The method of claim 1, further comprising refraining from communicating the triggered measurement report when the handover restraining criterion is not satisfied regardless of whether the reporting criterion is satisfied.
4. The method of claim 1, wherein the one or more network-provided parameters includes a first signal measurement offset to adjust a measurement result of the serving cell before evaluating the reporting criterion, and wherein the UE-configured parameter includes a second signal measurement offset that is greater than the first signal measurement offset such that the measurement result of the serving cell is adjusted to a greater value before evaluating the handover restraining criterion.
5. The method of claim 4, further comprising: determining the second signal measurement offset based on the first signal measurement offset and an adjustment value, wherein the adjustment value is based, at least in part, on a quantity of handover events during a preceding time period, a time since a previous handover event, a movement speed of the UE, or any combination thereof.
6. The method of claim 1, further comprising: determining a quantity of handover events during a preceding time period; determining a frequency of handovers based on the quantity of handover events during the preceding time period; and adjusting the UE-configured parameter of the handover restraining criterion based, at least in part, on the frequency of handovers.
7. The method of claim 1, wherein the handover restraining criterion cannot be satisfied until expiration of a delay timer initiated after a previous handover event, the method further comprising: setting a duration of the delay timer based, at least in part, on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiating the delay timer after the previous handover event.
8. The method of claim 7, wherein setting the duration of the delay timer includes: determining a frequency of handovers based on the quantity of handover events during the preceding time period; setting the duration to a first value when the frequency of handovers is below a handover frequency threshold; and setting the duration to a second value when the frequency of handovers is above the handover frequency threshold, the second value higher than the first value.
9. The method of claim 7, wherein setting the duration of the delay timer includes: setting the duration to a first value when the UE stationary; setting the duration to a second value when the UE is non-stationary and the movement speed of the UE is lower than a speed threshold, the second value lower than the first value; and setting the duration to a third value when the UE is non-stationary and the movement speed of the UE is higher than the speed threshold, the third value lower than the second value.
10. The method of claim 7, further comprising: determining whether a current signal strength of the first connection has changed more than a signal strength change threshold indicative that the UE has moved locations; and disabling the delay timer in response to a determination that the current signal strength of the first connection has changed more than the signal strength change threshold.
11. The method of claim 1 , wherein the UE-configured parameter limits the occurrence of the measurement reporting event such that the UE is prevented from ping-pong handovers between the serving cell and the neighbor cell.
12. The method of claim 1, further comprising: enabling the handover restraining criterion when the handover restraining criterion is disabled and a signal measurement of the serving cell is greater than a first signal strength threshold (RSRP High Threshold); and disabling the handover restraining criterion when the handover restraining criterion is enabled and the signal measurement of the serving cell is less than a second signal strength threshold (RSRP Low Threshold).
13. The method of claim 1 , wherein the measurement reporting event is an A3 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a corresponding signal measurement of the serving cell plus a first signal measurement offset (A3_offset), the A3_offset being one of the one or more network-provided parameters; and wherein the handover restraining criterion is satisfied when the signal measurement of the neighbor cell is higher than the corresponding signal measurement of the serving cell plus a second signal measurement offset (override_A3_offset), the override_A3_offset being the UE- configured parameter.
14. The method of claim 13, further comprising: determining that the A3_offset plus a hysteresis margin is less than an override threshold value; and generating the override_A3_offset based on the override threshold value minus the hysteresis margin.
15. The method of claim 1 , wherein the measurement reporting event is an A3 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a corresponding signal measurement of the serving cell plus a network-provided offset, and wherein the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
16. The method of claim 1 , wherein the measurement reporting event is an A4 event specified in a technical standard and the reporting criterion includes the signal measurement of the neighbor cell being greater than a network-provided threshold, and wherein the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is above a signal quality precondition threshold for a time period.
17. The method of claim 1 , wherein the measurement reporting event is an A5 event specified in a technical standard and the reporting criterion includes a current signal measurement of the first connection being below a first signal strength threshold and the signal measurement of the neighbor cell being greater than a second signal strength threshold, and wherein the handover restraining criterion is satisfied when a neighbor signal quality of the neighbor cell is higher than a current signal quality of the serving cell by at least a threshold amount for a time period.
18. The method of claim 1, wherein the handover restraining criterion includes one or more criterion selected from a group consisting of: an expiration of a delay timer that is initiated after a previous handover; a determination that a current signal strength of the first connection has changed more than a signal strength change threshold; a determination that a neighbor signal quality of the neighbor cell is higher than a current signal quality of the first connection by at least a threshold amount; a determination that the neighbor signal quality is above a signal quality precondition threshold; and a determination that the neighbor cell is not included in a network-provided cell blacklist.
19. The method of claim 1, wherein the measurement configuration includes a cell blacklist associated with the triggered measurement report, the method further comprising: determining whether the neighbor cell is in the cell blacklist; and communicating the triggered measurement report when both the reporting criterion and the handover restraining criterion are satisfied and the neighbor cell is not included in the cell blacklist.
20. The method of claim 1, wherein establishing at least the first connection includes: establishing the first connection with the serving cell of the BS in a Long-Term Evolution
(LTE) radio access network (RAN), the serving cell being designated as a primary serving cell; and establishing a second connection with a secondary serving cell of another BS in a 5G New Radio (NR) RAN.
21. A method for wireless communication performed by a first base station, comprising: establishing a connection with a user equipment (UE) via a serving cell of the first base station; preparing a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and transmitting a measurement configuration to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
22. The method of claim 21, wherein the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
23. The method of claim 21, wherein preparing the cell blacklist includes: determining a frequency of handover events associated with the neighbor cell based on the quantity of handover events over a time period; and including the neighbor cell in the cell blacklist if the frequency of handover events is above a threshold.
24. The method of claim 21, wherein preparing the cell blacklist includes: determining that the neighbor cell provides an overlapping geographic coverage area with the serving cell; determining that the UE is in a location of the overlapping geographic coverage area and that the quantity of handover events for the UE is higher than an average quantity of handover events for other UEs in other locations of the overlapping geographic coverage area; and including the neighbor cell in the cell blacklist for the UE.
25. A user equipment (UE), comprising: at least one modem configured to: establish at least a first connection with a serving cell of a base station (BS), and obtain a measurement configuration that includes a reporting criterion for a measurement reporting event, the reporting criterion configured to trigger the UE to send a triggered measurement report based, at least in part, on one or more network-provided parameters and a signal measurement of a neighbor cell, wherein the triggered measurement report is associated with initiating a handover of the UE from the serving cell to the neighbor cell; a processing system configured to monitor for an occurrence of measurement reporting event using a handover restraining criterion, the handover restraining criterion based, at least in part, on a UE-configured parameter different from the one or more network-provided parameters; and the at least one modem configured to communicate the triggered measurement report to the BS to indicate the occurrence of the measurement reporting event when both the reporting criterion and the handover restraining criterion are concurrently satisfied.
26. The UE of claim 25, wherein the processing system is further configured to: determine a quantity of handover events during a preceding time period; determine a frequency of handovers based on the quantity of handover events during the preceding time period; and adjust the UE-configured parameter of the handover restraining criterion based, at least in part, on the frequency of handovers.
27. The UE of claim 25, wherein the processing system is further configured to: set a duration of a delay timer based, at least in part, on a quantity of handover events during a preceding time period, a movement speed of the UE, or a combination thereof; and initiate the delay timer after a previous handover event, wherein the handover restraining criterion cannot be satisfied until expiration of the delay timer initiated after the previous handover event.
28. The UE of claim 25, further comprising: at least one transceiver coupled to the at least one modem; at least one antenna coupled to the at least one transceiver to wirelessly transmit signals output from the at least one transceiver and to wirelessly receive signals for input into the at least one transceiver; and a housing that encompasses at least the processing system, the at least one modem, the at least one transceiver, and at least a portion of the at least one antenna.
29. An apparatus of a first base station, comprising: a processing system configured to: establish a connection with a user equipment (UE) via a serving cell of the first base station, and prepare a cell blacklist that includes a neighbor cell of the first base station or a second base station based on a determination that a quantity of handover events in which the UE is handed over from the serving cell to the neighbor cell is above a threshold; and at least one modem configured to output a measurement configuration for transmission to the UE, the measurement configuration including the cell blacklist and a reporting criterion for a triggered measurement report.
30. The apparatus of claim 29, wherein the cell blacklist includes a list of one or more neighbor cells as an instruction for the UE to refrain from sending the triggered measurement report for the one or more neighbor cells included in the cell blacklist.
PCT/US2021/037199 2020-06-15 2021-06-14 Mitigation of excessive handovers in a wireless communication system WO2021257441A1 (en)

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