WO2021226983A1

WO2021226983A1 - Hysteresis increase for avoiding ping-pong between long term evolution cells in non-stand-alone mode

Info

Publication number: WO2021226983A1
Application number: PCT/CN2020/090441
Authority: WO
Inventors: Hao Zhang; Fojian ZHANG; Chaofeng HUI; Jian Li; Yuankun ZHU; Yi Liu; Tianya LIN
Original assignee: Qualcomm Incorporated
Priority date: 2020-05-15
Filing date: 2020-05-15
Publication date: 2021-11-18

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may determine, while connected to a long term evolution (LTE) cell in a New Radio non-stand-alone mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold. Numerous other aspects are provided.

Description

HYSTERESIS INCREASE FOR AVOIDING PING-PONG BETWEEN LONG TERM EVOLUTION CELLS IN NON-STAND-ALONE MODE

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for increasing hysteresis for avoiding ping-pong between Long Term Evolution cells in a New Radio non-stand-alone mode.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and/or the like) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) . A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New Radio (NR) , which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP) . NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a user equipment (UE) , may include determining, while connected to a long term evolution (LTE) cell in a New Radio (NR) non-stand-alone (NSA) mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.

In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to determine, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to determine, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.

In some aspects, an apparatus for wireless communication may include means for determining, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and means for increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 2 is a block diagram conceptually illustrating an example of a base station in communication with a UE in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 3 is a diagram illustrating an example of a UE ping-pong between two Long Term Evolution (LTE) cells in a New Radio (NR) non-stand-alone (NSA) mode, in accordance with various aspects of the present disclosure.

Fig. 4 is a diagram illustrating increasing hysteresis for avoiding ping-pong between LTE cells in an NR NSA mode, in accordance with various aspects of the present disclosure.

Fig. 5 is a diagram illustrating an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Fig. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, an NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/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 and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., 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 (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., 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 Fig. 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 (e.g., three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some aspects, 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 aspects, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Fig. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 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. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like. A UE may be a cellular phone (e.g., 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 (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., 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.

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, and/or the like, that may communicate with a base station, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/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, and/or the like. In some aspects, the processor components and the memory components may be coupled together. For example, the processor components (e.g., one or more processors) and the memory components (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, electrically coupled, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., 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 (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like) , a mesh network, and/or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the base station 110.

As indicated above, Fig. 1 is provided as an example. Other examples may differ from what is described with regard to Fig. 1.

Fig. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 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 ≥ 1.

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 (e.g., 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. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/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 (e.g., for OFDM and/or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., 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.

At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) 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 (e.g., 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/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , reference signal received quality (RSRQ) , channel quality indicator (CQI) , and/or the like. In some aspects, one or more components of UE 120 may be included in a housing.

Network controller 130 may include communication unit 294, controller/processor 290, and memory 292. Network controller 130 may include, for example, one or more devices in a core network. Network controller 130 may communicate with base station 110 via communication unit 294.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also 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 (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110. In some aspects, the UE 120 includes a transceiver. The transceiver may include any combination of antenna (s) 252, modulators and/or demodulators 254, MIMO detector 256, receive processor 258, transmit processor 264, and/or TX MIMO processor 266. The transceiver may be used by a processor (e.g., controller/processor 280) and memory 282 to perform aspects of any of the methods described herein, for example, as described with reference to Figs. 4 and 5.

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 controller/processor 240. Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. In some aspects, the base station 110 includes a transceiver. The transceiver may include any combination of antenna (s) 234, modulators and/or demodulators 232, MIMO detector 236, receive processor 238, transmit processor 220, and/or TX MIMO processor 230. The transceiver may be used by a processor (e.g., controller/processor 240) and memory 242 to perform aspects of any of the methods described herein, for example, as described with reference to Figs. 4 and 5.

Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with increasing hysteresis for avoiding ping-pong between Long Term Evolution (LTE) cells in a New Radio (NR) non-stand-alone (NSA) mode, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 500 of Fig. 5, and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. In some aspects, memory 242 and/or memory 282 may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, interpreting, and/or the like) by one or more processors of the base station 110 and/or the UE 120, may perform or direct operations of, for example, process 500 of Fig. 5, and/or other processes as described herein. In some aspects, executing instructions may include running the instructions, converting the instructions, compiling the instructions, interpreting the instructions, and/or the like. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for determining, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell, means for increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold, and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2, such as controller/processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and/or the like.

As indicated above, Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.

Fig. 3 is a diagram illustrating an example of a UE ping-pong between two LTE cells in an NR NSA mode, in accordance with various aspects of the present disclosure. Fig. 3 shows a signaling diagram for a UE (e.g., a UE 120 depicted in Figs. 1 and 2) , a first LTE cell ( “LTE Cell 1” ) and a second LTE cell ( “LTE cell 2” ) . In some aspects, any number of additional LTE cells may be included.

As shown by reference number 305, the UE and the LTE Cell 1 may engage in a packet switched (PS) data transfer. The PS data transfer may include uplink and/or downlink data. The PS data transfer may be facilitated by a radio resource control (RRC) connection between the UE and the LTE Cell 1. An NR NSA network may provide NR data service over the RRC connection, via the LTE Cell 1.

As shown by reference number 310, the UE may transmit a measurement report to the LTE Cell 1. In some aspects, the measurement report may include an event type A3 measurement report. In some aspects, for example, the UE may perform signal measurements associated with the serving cell, the LTE Cell 1, and neighboring cells, which may include the LTE Cell 2. The signal measurements may include, for example, reference signal received power (RSRP) measurements, reference signal received quality (RSRQ) measurements, and/or the like. Upon determining that a neighboring cell, the LTE Cell 2, may have a more favorable quality, power, and/or other characteristic, the UE may transmit the event type A3 measurement report to the LTE Cell 1. The UE may utilize a measurement report offset value, a hysteresis length, and/or the like to determine when to trigger the Event A3 and, thus, when to transmit the type A3 measurement report.

As shown by reference number 315, the LTE Cell 1 may transmit an RRC connection reconfiguration message to the UE based at least in part on receiving the measurement report from the UE. In some aspects, the LTE Cell 1 may evaluate the measurement report, which may include the obtained signal measurements, and, based at least on the measurement report, may trigger an RRC reconfiguration event to handover the UE to the LTE Cell 2.

As shown by reference number 320, the UE may perform the handover to the LTE Cell 2 (shown as “HO to Cell 2” ) . As shown by reference number 325, the UE may transmit a measurement report to the LTE Cell 2. In some aspects, the measurement report may include an A3 measurement report. In some aspects, the measurement report may be triggered by a process similar to that described above with regard to reference number 310. As shown by reference number 330, the LTE Cell 2 may transmit an RRC connection reconfiguration message to the UE based at least in part on the measurement report. As shown by reference number 335, the UE may perform a handover to the LTE Cell 1 (shown as “HO to Cell 1” ) based at least in part on receiving the RRC connection reconfiguration message.

As shown by reference number 340, the procedure described above in connection with reference numbers 310 –335 may repeat in a loop, causing the UE to handover between the LTE Cell 1 and LTE Cell 2 repetitively. This behavior may be referred to as a ping-pong between the two cells. A ping-pong between the two cells prevents the UE from maintaining data service and may cause the UE to waste power, processing resources, signaling resources, and/or the like, by repeatedly transmitting A3 measurement reports and performing handovers between the two cells.

According to various aspects of the techniques and apparatuses described herein, a procedure may be provided for increasing a hysteresis length, which may facilitate avoiding ping-pong between LTE cells. In some aspects, a UE may determine that a count of handovers between an LTE cell and at least one additional LTE cell satisfies a handover count threshold. The UE may increase a configured hysteresis length based at least in part on determining that the count of handovers satisfies the handover count threshold. In this way, immediate transmissions of A3 measurement reports may be avoided, thus avoiding repetitive handovers, which may facilitate consistent data service, conserving power, processing resources, signaling resources, and/or the like.

As indicated above, Fig. 3 is provided as an example. Other examples may differ from what is described with regard to Fig. 3.

Fig. 4 is a diagram illustrating an example of using a measurement report offset increase for avoiding ping-pong between LTE cells in an NR NSA mode, in accordance with various aspects of the present disclosure. Fig. 4 shows a signaling diagram for a UE (e.g., a UE 120 depicted in Figs. 1 and 2) , a first LTE cell ( “LTE Cell 1” ) and a second LTE cell ( “LTE cell 2” ) . In some aspects, any number of additional LTE cells may be included.

As shown by reference 405, the UE and the LTE Cell 1 may engage in a PS data transfer. As shown by reference number 410, the UE may transmit a measurement report to the LTE Cell 1. In some aspects, the measurement report may include an event type A3 measurement report. In some aspects, the UE may transmit the measurement report at a time determined based at least in part on a measurement report offset, a hysteresis length, and/or the like. In some aspects, a measurement report offset may be configured with a first value by the LTE Cell 1, the LTE Cell 2, and/or the like.

As shown by reference number 415, the LTE Cell 1 may transmit an RRC connection reconfiguration message to the UE based at least in part on receiving the measurement report from the UE. As shown by reference number 420, the UE may perform the handover to the LTE Cell 2.

In some aspects, as shown by reference number 425, the UE may determine whether a first handover condition (shown as “c1” ) is satisfied. In some aspects, to determine whether the first handover condition is satisfied, the UE may determine whether the handover to the LTE Cell 2 is the first handover (since the last iteration of the procedure described herein) . If the handover is the first handover, as shown by reference number 430, the UE may initiate a timer (shown as “T_HO_GUARD” ) . The value of the timer may be configured by the LTE Cell 1, the LTE Cell 2, and/or the like. In some aspects, the value of the timer may include any amount of time (e.g., sixty seconds, and/or the like) . In some aspects, the UE may stop the timer based at least in part on determining that an RRC connection (e.g., the RRC connection between the UE and the LTE Cell 1, the LTE Cell 2, and/or the like) is released.

As shown by reference number 435, if the timer is initiated (e.g., if the handover was not the first handover, if the handover was the first handover and the timer is initiated, and/or the like) , the UE may determine whether a second handover condition (shown as “c2” ) is satisfied. In some aspects, to determine whether the second handover condition is satisfied, the UE may determine whether a count of handovers between the LTE Cell 1 and at least one additional LTE cell (e.g., LTE Cell 2, and/or the like) satisfies a handover count threshold (shown as “MAX_HO” ) . In some aspects, determining that the count of handovers satisfies the handover count threshold includes determining that the count of handovers satisfies the handover count threshold before expiration of the timer.

As shown by reference number 440, if the count of handovers does not satisfy the handover count threshold, the UE may transmit a measurement report to the LTE Cell 2, which may be triggered by a process similar to that described above with regard to reference number 310 shown in Fig. 3. In some aspects, the measurement report may include an A3 measurement report. As shown by reference number 445, the LTE Cell 2 may transmit an RRC connection reconfiguration message to the UE based at least in part on the measurement report. As shown by reference number 450, the UE may perform a handover to the LTE Cell 1. As shown by reference number 455, the UE may determine whether the first handover condition and/or the second handover condition are satisfied. As shown by reference number 460, the UE may loop the procedure described above in connection with reference numbers 410-455.

As shown by reference number 465, the UE may increase the hysteresis length by a second value (shown as “Use Hyst_long” ) . In some aspects, the UE may increase the hysteresis length to a value that is a sum of the configured first value and the second value. That sum is shown in Fig. 4 as “Hyst_long. ” In some aspects, the second value may be any amount of time. In some aspects, the second value may include one hundred seconds, and/or the like. In some aspects, as shown in Fig. 4, the UE may increase the hysteresis length by the second value based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.

As shown by reference number 470, the UE may start a specified time duration timer (shown as “T_Bar_HO” ) associated with the second value. In some aspects, the specified time duration may be configured by the LTE Cell 1, LTE Cell 2, and/or the like. In some aspects, the specified time duration may include any duration of time (e.g., ten minutes, and/or the like) . In some aspects, the UE may decrease the hysteresis length to the first value based at least in part on expiration of the specified time duration, T_Bar_HO, associated with the second value.

In some aspects, the UE may decrease the hysteresis length to the first value based at least in part on determining that an RRC connection (e.g., the RRC connection between the UE and the LTE Cell 1, the LTE Cell 2, and/or the like) is released. In some aspects, the UE may decrease the hysteresis length to the first value based at least in part on determining that an LTE Event A2 is triggered.

As indicated above, Fig. 4 is provided as an example. Other examples may differ from what is described with regard to Fig. 4.

Fig. 5 is a diagram illustrating an example process 500 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 500 is an example where the UE (e.g., UE 120 and/or the like) performs operations associated with increasing hysteresis for avoiding ping-pong between LTE cells in NR NSA mode.

As shown in Fig. 5, in some aspects, process 500 may include determining, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell (block 510) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may determine, while connected to an LTE cell in an NR NSA mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, as described above. In some aspects, a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell.

As further shown in Fig. 5, in some aspects, process 500 may include increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold (block 520) . For example, the UE (e.g., using controller/processor 280, memory 282, and/or the like) may increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold, as described above.

Process 500 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the hysteresis length corresponds to an LTE Event A3 hysteresis.

In a second aspect, alone or in combination with the first aspect, process 500 includes decreasing the hysteresis length to the first value based at least in part on determining that an RRC connection is released.

In a third aspect, alone or in combination with one or more of the first and second aspects, process 500 includes decreasing the hysteresis length to the first value based at least in part on determining that an LTE Event A2 is triggered.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 500 includes decreasing the hysteresis length to the first value based at least in part on expiration of a specified time duration associated with the second value.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process 500 includes receiving a configuration of the specified time duration.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, determining that the count of handovers satisfies the handover count threshold includes determining that the count of handovers satisfies the handover count threshold before expiration of a timer.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process 500 includes stopping the timer based at least in part on determining that an RRC connection is released.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process 500 includes receiving a configuration of the timer.

Although Fig. 5 shows example blocks of process 500, in some aspects, process 500 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 5. Additionally, or alternatively, two or more of the blocks of process 500 may be performed in parallel.

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.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

As used herein, satisfying a threshold may, depending on the context, 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, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication performed by a user equipment (UE) , comprising:

determining, while connected to a long term evolution (LTE) cell in a New Radio non-stand-alone mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and

increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.
The method of claim 1, wherein the hysteresis length corresponds to an LTE Event A3 hysteresis.
The method of claim 1, further comprising decreasing the hysteresis length to the first value based at least in part on determining that a radio resource control connection is released.
The method of claim 1, further comprising decreasing the hysteresis length to the first value based at least in part on determining that an LTE Event A2 is triggered.
The method of claim 1, further comprising decreasing the hysteresis length to the first value based at least in part on expiration of a specified time duration associated with the second value.
The method of claim 5, further comprising receiving a configuration of the specified time duration.
The method of claim 1, wherein determining that the count of handovers satisfies the handover count threshold includes determining that the count of handovers satisfies the handover count threshold before expiration of a timer.
The method of claim 7, further comprising stopping the timer based at least in part on determining that a radio resource control connection is released.
The method of claim 7, further comprising receiving a configuration of the timer.
A user equipment for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

determine, while connected to a long term evolution (LTE) cell in a New Radio non-stand-alone mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and

increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment, cause the one or more processors to:

determine, while connected to a long term evolution (LTE) cell in a New Radio non-stand-alone mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and

increase the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.
An apparatus for wireless communication, comprising:

means for determining, while connected to a long term evolution (LTE) cell in a New Radio non-stand-alone mode, that a count of handovers between the LTE cell and at least one additional LTE cell satisfies a handover count threshold, wherein a hysteresis length is configured with a first value by the LTE cell and the at least one additional LTE cell; and

means for increasing the hysteresis length by a second value, based at least in part on determining that the count of handovers between the LTE cell and the at least one additional LTE cell satisfies the handover count threshold.