WO2021056238A1

WO2021056238A1 - Frequency band prioritization for wireless communications

Info

Publication number: WO2021056238A1
Application number: PCT/CN2019/107722
Authority: WO
Inventors: Nanrun WU; Harish Venkatachari; Jie Mao; Supratik Bhattacharjee; Jinghua Fang
Original assignee: Qualcomm Incorporated
Priority date: 2019-09-25
Filing date: 2019-09-25
Publication date: 2021-04-01

Abstract

This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for biasing coupling on a frequency band to lower frequency bands or FDD bands instead of TDD bands. In one aspect, an example method includes determining, by a first device, whether a speed of the first device may be greater than a threshold speed. The method also includes coupling the first device to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed. The first frequency band is a lower frequency than the second frequency band. The method also may include biasing toward the first frequency band instead of the second frequency band based on determining that the speed of the first device may be greater than the threshold speed.

Description

FREQUENCY BAND PRIORITIZATION FOR WIRELESS COMMUNICATIONS

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and for example, to frequency band prioritization for wireless communications.

DESCRIPTION OF THE RELATED TECHNOLOGY

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. 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, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate on a municipal, national, regional, and even global level. Example telecommunication standards include 4G Long Term Evolution (LTE) and 5G New Radio (NR) . 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (such as with Internet of Things (IoT) ) , and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB) , massive machine type communications (mMTC) , and ultra-reliable low latency communications (URLLC) . Some aspects of 5G NR may be based on the 4G LTE standard. There exists a need for further improvements in 4G LTE and 5G NR technologies. These improvements also may be applicable to other radio access technologies or telecommunication standards that employ these technologies.

SUMMARY

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 an example method including determining, by a first device, whether a speed of the first device may be greater than a threshold speed. The method also includes coupling the first device to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed. The first frequency band is a lower frequency than the second frequency band.

In another aspect, another example method includes coupling, by a first device, to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex band and the second frequency band being a time division duplex band.

In a further aspect, another example method includes receiving, by a user equipment, an indicator from a cell of a network that the network is a high speed train network. The cell is coupled to the UE on a first frequency band. The method also includes determining a scheduling rate of the UE on the first frequency band. When the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band, the method may include measuring a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the first frequency band and, in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold, increasing an A3 event offset of an A3 handover event by a first offset bias and increasing an A4 event threshold of an A4 handover event by a first threshold bias. When the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band and in response to the scheduling rate being less than a second rate threshold, the method may include decreasing the A3 event offset of the A3 handover event by a second offset bias and decreasing the A4 event threshold of the A4 handover event by a second threshold bias.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an example apparatus including a processing system configured to determine whether a speed of a first device may be greater than a threshold speed. The apparatus also includes a first interface configured to output a request to couple the first device to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed. The first frequency band is a lower frequency than the second frequency band.

In another aspect, another example apparatus includes a processing system configured to determine to couple a first device to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex band and the second frequency band being a time division duplex band.

In a further aspect, another example apparatus includes a processing system configured to process an indicator from a cell of a network that the network is a high speed train network. The cell is coupled to a user equipment (UE) on a first frequency band. The processing system is further configured to determine a scheduling rate of the UE on the first frequency band. When the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band, the processing system may be configured to measure a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the first frequency band and, in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold, increase an A3 event offset of an A3 handover event by a first offset bias and increase an A4 event threshold of an A4 handover event by a first threshold bias. When the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band and in response to the scheduling rate being less than a second rate threshold, the processing system may be configured to decrease the A3 event offset of the A3 handover event by a second offset bias and decrease the A4 event threshold of the A4 handover event by a second threshold bias.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an example non-transitory, computer readable medium including instructions that, when executed by a processor of a first device, cause the first device to determine whether a speed of the first device may be greater than a threshold speed. Execution of the instructions also causes the first device to couple to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed. The first frequency band is a lower frequency than the second frequency band.

In another aspect, another example computer readable medium includes instructions that, when executed by a processor of a first device, cause the first device to couple to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex band and the second frequency band being a time division duplex band.

In a further aspect, another example computer readable medium includes instructions that, when executed by a processor of a user equipment (UE) , cause the UE to receive an indicator from a cell of a network that the network is a high speed train network. The cell is coupled to the UE on a first frequency band. Execution of the instructions also cause the UE to determine a scheduling rate of the UE on the first frequency band. When the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band, execution of the instructions may cause the UE to measure a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the first frequency band and, in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold, increase an A3 event offset of an A3 handover event by a first offset bias and increase an A4 event threshold of an A4 handover event by a first threshold bias. When the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band and in response to the scheduling rate being less than a second rate threshold, execution of the instructions may cause the UE to decrease the A3 event offset of the A3 handover event by a second offset bias and decrease the A4 event threshold of the A4 handover event by a second threshold bias.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a device including means for determining whether a speed of the device may be greater than a threshold speed. The device also includes means for coupling the device to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the device may be greater than the threshold speed. The first frequency band is a lower frequency than the second frequency band.

In another aspect, another example device includes means for coupling to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex band and the second frequency band being a time division duplex band.

In a further aspect, another example device includes means for receiving an indicator from a cell of a network that the network is a high speed train network. The cell is coupled to the device on a first frequency band. The device also includes means for determining a scheduling rate of the device on the first frequency band. When the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band, the device include means for measuring a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the first frequency band and, in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold, means for increasing an A3 event offset of an A3 handover event by a first offset bias and means for increasing an A4 event threshold of an A4 handover event by a first threshold bias. When the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band and in response to the scheduling rate being less than a second rate threshold, the device may include means for decreasing the A3 event offset of the A3 handover event by a second offset bias and means for decreasing the A4 event threshold of the A4 handover event by a second threshold bias.

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

Figure 1 is a diagram illustrating an example of a wireless communications system and an access network.

Figure 2 is a diagram illustrating an example of a base station and user equipment (UE) in an access network.

Figure 3 is a diagram illustrating an example wireless communication device.

Figure 4A is a diagram illustrating an example device including an example wireless communication device.

Figure 4B is a diagram illustrating an example user equipment on a high speed train causing a doppler effect for wireless communications between a cell and the user equipment.

Figure 5 is a flowchart of an example method of wireless coupling on a lower frequency band instead of a higher frequency band.

Figure 6 is a flowchart of an example method of wireless coupling on a frequency division duplex frequency band instead of on a time division duplex band.

Figure 7 is a flowchart of an example method of determining a scheduling rate to a user equipment.

Figure 8 is a flowchart of an example method of biasing wireless coupling on a high speed train wireless network.

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

The following description is directed to some particular implementations for the purposes of describing 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. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving radio frequency (RF) signals according to one or more of the Long Term Evolution (LTE) , 3G, 4G or 5G (New Radio (NR) ) standards promulgated by the 3rd Generation Partnership Project (3GPP) , the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, the IEEE 802.15 standards, or the

standards as defined by the Bluetooth Special Interest Group (SIG) , among others. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal FDMA (OFDMA) , single-carrier FDMA (SC-FDMA) , single-user (SU) multiple-input multiple-output (MIMO) and multi-user (MU) MIMO. The described implementations also can be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless wide area network (WWAN) , a wireless personal area network (WPAN) , a wireless local area network (WLAN) , or an internet of things (IOT) network.

Various implementations relate generally to frequency band prioritization for wireless communications. Some implementations more specifically relate to biasing toward lower frequency bands for wireless communications. A device, such as a user equipment (UE) , may be configured to wirelessly couple with another device, such as a base station (BS) , via at least one of a plurality of different frequency bands. If the device is moving, doppler effect may interfere with communications on the selected frequency band. However, wireless communications may be less affected on a lower frequency band than on a higher frequency band, and wireless communications may have a higher throughput on the lower frequency band than the higher frequency band. As a result, the device may bias toward being wirelessly coupled to the other device on the lower frequency band.

Some other implementations relate to biasing toward frequency division duplex (FDD) bands for wireless communications. A UE may be configured to wirelessly couple with a BS via at least one or more FDD bands and one or more time division duplex (TDD) bands. Wireless communications on an FDD band includes different frequencies for uplink (UL) traffic from the UE to the BS and downlink (DL) traffic from the BS to the UE, which may allow for concurrent transmission of UL traffic and DL traffic. Wireless communications on a TDD band includes the same frequency for UL traffic and DL traffic, and DL traffic and UL traffic are not transmitted concurrently. If the channel size of the FDD band and the channel size of the TDD band are the same (such as 20 MHz, 40 MHz, etc. ) , the throughput may be higher for wireless communications on the FDD band than on the TDD band. As a result, the device may bias toward being wireless coupled to the other device on an FDD band.

In this manner, a UE may adjust when to hand over to another BS or cell for switching frequency bands. For example, the UE may adjust if and when to announce a handover event to the current BS to which the UE is coupled. In some implementations, the biasing toward a lower frequency band or an FDD band may be based on network resources for the frequency band. For example, a UE may observe a scheduling rate of the currently coupled BS to determine if too many UEs are coupled to the same BS or are using the same frequency band. In this manner, a device may adjust if and when to bias coupling to a lower frequency band or an FDD band.

Particular implementations of the subject matter described in this disclosure can be implemented to realize higher throughputs for devices communicating on the network. The particular implementations also can be implemented to balance network resources among a plurality of devices coupled to the wireless network while increasing throughputs of wireless communications for the specific device.

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

By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems on a chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example implementations, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

Figure 1 is a diagram illustrating an example of a wireless communications system and an access network 100. The wireless communications system (also referred to as a wireless wide area network (WWAN) ) includes base stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and another core network 190 (such as a 5G Core (5GC) ) . The base stations 102 may include macrocells (high power cellular base station) or small cells (low power cellular base station) . The macrocells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through backhaul links 132 (such as an S1 interface) . The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN) ) may interface with core network 190 through backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (such as handover, dual connectivity) , inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS) , subscriber and equipment trace, RAN information management (RIM) , paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (such as through the EPC 160 or core network 190) with each other over backhaul links 134 (such as an X2 interface) . The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102' may have a coverage area 110' that overlaps the coverage area 110 of one or more macro base stations 102. One or more base stations 102 may include a number of repeaters (such as one or two repeaters) to extend the coverage area of the base station 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network also may include Home Evolved Node Bs (eNBs) (HeNBs) , which may provide service to a restricted group known as a closed subscriber group (CSG) . The communication links 120 between the base stations 102 and the UEs 104 may include UL (also referred to as reverse link) transmissions from a UE 104 to a base station 102 or DL (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, or transmit diversity. The communication links may be through one or more carriers. The base stations 102 /UEs 104 may use spectrum up to Y MHz (such as 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (such as more or fewer carriers may be allocated for DL than for UL) . The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell) .

Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , and a physical sidelink control channel (PSCCH) . D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum (or other suitable frequency spectrum) . When communicating in an unlicensed frequency spectrum, the STAs 152 /AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell 102' may operate in a licensed or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP 150. The small cell 102', employing NR in an unlicensed frequency spectrum, may boost coverage to or increase capacity of the access network.

A base station 102, whether a small cell 102' or a large cell (such as macro base station) , may include an eNB, gNodeB (gNB) , or another type of base station. Some base stations, such as gNB 180, may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, or near mmW frequencies in communication with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW /near mmW radio frequency band (such as 3 GHz –300 GHz) has extremely high path loss and a short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182'. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182” . The UE 104 also may transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180 /UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 /UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network 190 may include an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, or other IP services.

The base station also may be referred to as a gNB, Node B, evolved Node B (eNB) , an access point (AP) , a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a transmit reception point (TRP) , or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA) , a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (such as an MP3 player) , a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (such as a parking meter, gas pump, toaster, vehicles, heart monitor, etc. ) . The UE 104 also may be referred to as a station (STA) , a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again to Figure 1, in certain aspects, a UE 104 may be configured to bias coupling to a wireless network (including the base station 180) via a first frequency band over a second frequency band. In some implementations, the UE 104 is configured to adjust when to announce a handover event to a base station (such as the base station 180) . In some other implementations, the UE 104 is configured to observe resource allocation from a base station in order to determine if or when to announce a handover event to the base station. Although the description herein may be focused on LTE communications, the concepts described may be applicable to other wireless communication areas, such as but not limited to 5G NR, LTE-A, CDMA, GSM, Wi-Fi, and other wireless technologies.

Figure 2 is a block diagram of a base station 210 in communication with a UE 250 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller/processor 275. The controller/processor 275 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor 275 provides RRC layer functionality associated with broadcasting of system information (such as an MIB, SIBs) , RRC connection control (such as RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release) , inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification) , and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs) , error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs) , re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs) , demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 216 and the receive (RX) processor 270 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, scrambling/descrambling of payloads, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 216 handles mapping to signal constellations based on various modulation schemes (such as binary phase-shift keying (BPSK) , quadrature phase-shift keying (QPSK) , M-phase-shift keying (M-PSK) , M-quadrature amplitude modulation (M-QAM) ) . The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (such as a pilot signal) in the time or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 274 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal or channel condition feedback transmitted by the UE 250. Each spatial stream may then be provided to a different antenna 220 via a separate transmitter 218TX. Each transmitter 218TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 250, each receiver 254RX receives a signal through its respective antenna 252. Each receiver 254RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 256. The TX processor 268 and the RX processor 256 implement layer 1 functionality associated with various signal processing functions. The RX processor 256 may perform spatial processing on the information to recover any spatial streams destined for the UE 250. If multiple spatial streams are destined for the UE 250, they may be combined by the RX processor 256 into a single OFDM symbol stream. The RX processor 256 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 210. These soft decisions may be based on channel estimates computed by the channel estimator 258. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 210 on the physical channel. The data and control signals are then provided to the controller/processor 259, which implements layer 3 and layer 2 functionality.

The controller/processor 259 can be associated with a memory 260 that stores program codes and data. The memory 260 may be referred to as a computer-readable medium. In the UL, the controller/processor 259 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 259 is also responsible for error detection using an ACK or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station 210, the controller/processor 259 provides RRC layer functionality associated with system information (such as MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression /decompression, and security (ciphering, deciphering, integrity protection, integrity verification) ; RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 258 from a reference signal or feedback transmitted by the base station 210 may be used by the TX processor 268 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 268 may be provided to different antenna 252 via separate transmitters 354TX. Each transmitter 254TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 210 in a manner similar to that described in connection with the receiver function at the UE 250. Each receiver 218RX receives a signal through its respective antenna 220. Each receiver 218RX recovers information modulated onto an RF carrier and provides the information to a RX processor 270.

The controller/processor 275 can be associated with a memory 276 that stores program codes and data. The memory 276 may be referred to as a computer-readable medium. In the UL, the controller/processor 275 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the UE 250. IP packets from the controller/processor 275 may be provided to the EPC 160. The controller/processor 275 is also responsible for error detection using an ACK or NACK protocol to support HARQ operations. Information to be wirelessly communicated (such as for LTE and NR based communications) is encoded and mapped, at the PHY layer, to one or more wireless channels for transmission.

Figure 3 is a diagram of an example wireless communication device 300. In some implementations, the wireless communication device 300 can be an example of a device for use in a UE (or STA) , such as the UE 250 described above with reference to Figure 2. In some implementations, the wireless communication device 300 can be an example of a device for use in a cell, such as the base station 210 described above with reference to Figure 2, or an AP. The wireless communication device 300 is capable of transmitting (or outputting for transmission) and receiving wireless communications (for example, in the form of wireless packets) .

The wireless communication device 300 can be, or can include, a chip, system on chip (SoC) , chipset, package or device that includes one or more modems 302. The one or more modems 302 (collectively “the modem 302” ) may include, for example, one or more of a WWAN modem (for example, an LTE or 5G NR compliant modem) or a WLAN (such as IEEE 802.11 compliant) modem. In some implementations, the wireless communication device 300 also includes one or more radios 304 (collectively “the radio 304” ) . In some implementations, the wireless communication device 300 further includes one or more processors, processing blocks or processing elements 306 (collectively “the processor 306” ) and one or more memory blocks or elements 308 (collectively “the memory 308” ) .

The modem 302 can include an intelligent hardware block or device such as, for example, an application-specific integrated circuit (ASIC) among other possibilities. The modem 302 is generally configured to implement a PHY layer. For example, the modem 302 is configured to modulate packets and to output the modulated packets to the radio 304 for transmission over the wireless medium. The modem 302 is similarly configured to obtain modulated packets received by the radio 304 and to demodulate the packets to provide demodulated packets. In addition to a modulator and a demodulator, the modem 302 may further include digital signal processing (DSP) circuitry, a coder, a decoder, a multiplexer and a demultiplexer. For example, while in a transmission mode, data obtained from the processor 306 is provided to a coder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points in a modulation constellation to provide modulated symbols. The modulated symbols may then be mapped and provided to DSP circuitry for filtering. The digital signals may then be provided to a digital-to-analog converter (DAC) . The resultant analog signals may then be provided to a frequency upconverter, and ultimately, the radio 304.

While in a reception mode, digital signals received from the radio 304 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 is coupled with the demodulator, which is configured to extract modulated symbols from the signal. The demodulator is coupled with the decoder, which may be configured to decode the modulated bits. The decoded bits may then be provided to the MAC layer (such as the processor 306) for processing, evaluation or interpretation.

The radio 304 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 300 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 302 are provided to the radio 304, which then transmits the symbols via the coupled antennas. Similarly, symbols received via the antennas are obtained by the radio 304, which then provides the symbols to the modem 302.

The processor 306 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 306 processes information received through the radio 304 and the modem 302, and processes information to be output through the modem 302 and the radio 304 for transmission through the wireless medium. For example, the processor 306 may implement a control plane and MAC layer configured to perform various operations related to the generation and transmission of packets. The MAC layer is configured to perform or facilitate the coding and decoding of frames, spatial multiplexing, space-time block coding (STBC) , beamforming, and OFDMA resource allocation, among other operations or techniques. In some implementations, the processor 306 may generally control the modem 302 to cause the modem to perform various operations described above.

The memory 308 can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM) , or combinations thereof. The memory 308 also can store non-transitory processor-or computer-executable software (SW) code containing instructions that, when executed by the processor 306, cause the device 300 to perform various operations described herein for wireless communication. 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.

Figure 4A is a diagram illustrating an example device 400. The device 400 can be an example implementation of the UE 250 described with reference to Figure 2, or a STA. The device 400 includes a wireless communication device 415 (although the device 400 may itself also be referred to generally as a wireless communication device as used herein) . For example, the wireless communication device 415 may be an example implementation of the wireless communication device 300 described with reference to Figure 3. The device 400 also includes one or more antennas 425 coupled with the wireless communication device 415 to transmit and receive wireless communications. The device 400 additionally includes an application processor 435 coupled with the wireless communication device 415, and a memory 445 coupled with the application processor 435. In some implementations, the device 400 further includes a user interface (UI) 455 (such as a touchscreen or keypad) and a display 465, which may be integrated with the UI 455 to form a touchscreen display. In some implementations, the device 400 may further include one or more sensors 475 such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, altitude sensors, or a Global Positioning System (GPS) sensor. While not shown, the device 400 also may include one or more microphones, one or more speakers, one or more cameras, or one or more light sources (such as a light emitting diode configured as a camera flash) . In some implementations, the device 400 may include one or more of a graphics processor, an image signal processor, an audio codec, or a security processing unit. In some implementations, the application processor 435 may include one or more of the aforementioned components. One or more of the components can communicate with other one or more of the components directly or indirectly, over at least one bus. The device 400 further may include a housing that encompasses the wireless communication device 415, the application processor 435, the memory 445, and at least portions of the antennas 425, UI 455, and display 465.

While the examples and illustrations herein are with reference to the device 400, any suitable device (such as the wireless communication device 300 in Figure 3) or any suitable device configuration may be used in performing aspects of the disclosure. The provided examples are therefore to be viewed as describing aspects of the disclosure and not in a limiting sense.

The LTE standard defines a plurality of frequency bands for wireless communication between a UE and a cell (such as the UE 250 and the base station 210 in Figure 2) . For example, release 8 of the LTE standard from the 3GPP defines band 3 for use globally and band 39 for use in China. Release 10 of the LTE standard from the 3GPP defines band 41 for use globally. Band 3 is defined for FDD communications, and band 39 and band 41 are defined for TDD communications. Each band configured for FDD communications may be referred to herein as an FDD band, and each band configured for TDD communications may be referred to herein as a TDD band. The frequency for DL traffic on band 3 is centered at approximately 1842.5 MHz, the frequency for UL traffic on band 3 is centered at approximately 1747.5 MHz, and the bandwidth for each of UL and DL communications is 75 MHz. For band 39, the frequency for UL and DL traffic is centered at 1900 MHz with a 40 MHz bandwidth. For band 41, the frequency for UL and DL traffic is centered at approximately 2593 MHz with a 194 MHz bandwidth.

While multiple examples herein refer to

LTE frequency bands

3, 39, and 41, some implementations may be directed to other frequencies and wireless technologies. For example, the various releases of the LTE standard define other FDD and TDD frequency bands for wireless communications. Additionally, various 5G NR bands are defined (or are to be defined) in the standard. Some other implementations may be directed to switching between different frequency bands or channels of a different radio access technology (such as between 2.4 GHz and 5 GHz, or between channels within the 2.4 GHz frequency band, for WLAN) . Some further implementations may be directed to telecommunications (or other wireless communications) in unlicensed or open frequencies or yet to be licensed frequencies that are defined or to be defined.

Outside of interference, signal strength, or other signal quality metrics, a carrier frequency, number of UEs coupled to a cell, the bandwidth of the frequency band, and whether the frequency band is an FDD band or a TDD band affect the throughput of wireless communications between a UE and a cell. For example, assuming the same signal quality and similar device performance for a first UE coupled to a first cell on band 3 and a second UE coupled to a second cell on band 39, the throughput of wireless communications for the first UE should be higher than the throughput of wireless communications for the second UE. The difference in throughput may be based on the difference in bandwidth (such as 75 MHz versus 40 MHz) and band 3 being an FDD band versus band 39 being a TDD band.

A carrier signal of a lower frequency band has a longer wavelength than a carrier signal of a higher frequency band. If a UE is not moving or is moving slowly (such as a person walking with his or her smartphone) , a higher frequency band may be associated with a higher potential throughput because of the higher frequency of the carrier signal. For example, band 30 may be associated with a higher possible throughput than band 3. As a result, excluding network balancing based on number of UEs and excluding signal strength or quality measurements, many UEs and networks may bias UEs to couple to a cell on a higher frequency band. For example, UEs in North America may be configured to prefer coupling on band 30 instead of band 3. However, a doppler effect caused by a velocity of a UE moving away from or towards a cell (or a STA moving away or towards an AP) affects the frequency of wireless communications in a lower frequency band less than the frequency of wireless communications in a higher frequency band.

Figure 4B is a diagram illustrating an example of a UE 480 on a high speed train 482 moving towards a cell 484 to cause a doppler effect for wireless communications between the cell 484 and the UE 480. Figure 4B also illustrates an example of a UE 490 on a high speed train 492 moving away from a cell 494 to cause a doppler effect for wireless communications between the cell 494 and the UE 490. Referring to the example of the high speed train 482 moving towards the cell 484, a carrier signal 486 may be used for wireless communication between the UE 480 (on the high speed train 482) and the cell 484. Since the high speed train 482 is moving towards the cell 484, the carrier signal received at the cell 484 for UL transmissions and at the UE 480 for DL transmissions (as illustrated by signal 488) will be at a higher frequency than the carrier signal 486 when transmitted. For example, if the frequency of the carrier signal 486 is 1800 MHz, the train 482 is travelling at 200 kilometers per hour (kph) , and radio waves are assumed to travel at approximately the speed of light, the observed frequency of the signal 488 is approximately 2130 MHz. The observed frequency of signal 488 is approximately 330 MHz greater than the frequency of the carrier signal 486 transmitted at 1800 MHz. If the frequency of the carrier signal 486 is 2100 MHz, the observed frequency of the signal 488 is approximately 2490 MHz. The observed frequency of signal 488 is approximately 390 MHz greater than the frequency of the carrier signal 486 transmitted at 2100 MHz.

Referring to the example of the high speed train 492 moving away from the cell 494, a carrier signal 496 may be used for wireless communication between the UE 490 (on the high speed train 492) and the cell 494. Since the high speed train 492 is moving away from the cell 494, the carrier signal received at the cell 494 for UL transmissions and at the UE 490 for DL transmissions (as illustrated by signal 498) will be at a lower frequency than the carrier signal 496 when transmitted. For example, if the frequency of the carrier signal 496 is 1800 MHz, the train 492 is travelling at 200 kilometers per hour (kph) , and radio waves are assumed to travel at approximately the speed of light, the observed frequency of the signal 498 is approximately 1520 MHz. The observed frequency of signal 498 is approximately 280 MHz less than the frequency of the carrier signal 496 transmitted at 1800 MHz. If the frequency of the carrier signal 496 is 2100 MHz, the observed frequency of the signal 498 is approximately 1770 MHz. The observed frequency of signal 498 is approximately 330 MHz less than the frequency of the carrier signal 496 transmitted at 2100 MHz.

As shown, a doppler effect causes a larger difference between the observed frequency of a higher frequency transmitted signal than a lower frequency transmitted signal. In the above example of the train 482 moving towards the cell 484 at 200 kph, the doppler effect causes a shift in frequency that differs by approximately 60 MHz between a signal transmitted at 1800 MHz and 2100 MHz. A receiver attempts to correlate the received signal to the correct frequency band. The receiver may have more difficulties correlating and decoding a received signal to the appropriate frequency band when the signal’s frequency is further from the frequency band. A receiver also may be configured to expect signals having frequencies of the frequency band. The greater the difference between the frequency band and the frequency of the received signal, the more difficulty the receiver may have in correctly receiving the signal. In this manner, transmissions at a higher frequency are more affected by motion (as a result of the doppler effect) than transmissions at a lower frequency.

As an example, UL transmissions in frequency band 3 (centered around approximately 1747.5 MHz, as indicated above) are less affected by motion of the UE than UL transmission in frequency band 39 (centered around 1900 MHz) . The doppler effect may increase as the velocity of the UE increases, which may increase the impact on higher frequency band communications as compared to lower frequency band communications. As a result, any potential gains in throughput based on a higher frequency band may be less than the reduction of throughput caused by a doppler effect. In this manner, the throughput for lower frequency band communications may be greater than the throughput for higher frequency band communications as a result of UE movements. For example, if a device is located in a car traveling along a high speed road or the device is located on a high speed train, the throughput of communications between a UE and the serving cell on a lower frequency band may be greater than the throughput of communications between the UE and the serving cell on a higher frequency band. In some implementations, a UE may be configured to bias toward coupling to the network on a lower frequency band than on a higher frequency band based on a movement or potential movement of the UE.

Figure 5 is a flowchart of an example method 500 of wireless coupling on a lower frequency band instead of a higher frequency band. At 502, a device 400 may determine whether a speed of the device may be greater than a threshold speed. For example, a UE may determine whether the UE is moving at a speed greater than a threshold speed or whether the UE is likely to move at a speed greater than a threshold speed. The threshold speed may be any suitable threshold, such as a speed associated with a doppler effect having a similar impact as a higher carrier frequency between the first frequency band and the second frequency band. The threshold may be set by the network or the device, and may be static or dynamic based on other factors (such as the bandwidth of one or more of the channels, whether the frequency band is an FDD band or a TDD band) .

In some implementations, a device 400 may measure the speed based on one or more sensors 475 (such as a GPS sensor, inertial sensor, etc. ) , and compare the measured speed to a threshold speed. In some other implementations, the device 400 may determine that the device 400 is likely to move at a speed greater than the threshold speed based on a location of the device 400. For example, the device 400 may use a GPS sensor or other locationing means to determine a geographic location of the device 400. Some geographic locations may be associated with determining a likely speed to be greater than the threshold speed. For example, the location of a high speed train rail or station may be associated with a speed greater than the threshold speed. If the device 400 determines its location to be at a high speed train rail or station, the device 400 may determine that the likely speed is to be greater than the threshold speed.

In some further implementations, the device 400 may estimate or simulate a doppler effect on wireless communications. For example, a UE may periodically measure the Reference Signals Received Power (RSRP) , and the UE may estimate a doppler profile based on changes over time in the RSRP. The estimated doppler profile then may be used to simulate or estimate a doppler effect on wireless communications with a cell. In this manner, the UE determining whether the UE may go faster than the threshold speed may be based on the simulated or estimated doppler effect.

In one example, a threshold speed may include the speed at which the doppler effect lowers a maximum throughput of a first frequency band to the maximum throughput of a second frequency band. In another example, a threshold speed may be a defined speed to differentiate between different means of transportation. For example, a threshold speed of 120 miles per hour (mph) or 192 kilometers per hour (kph) , may differentiate between a first group of transportation means of walking, bicycling, automobiles, city trains, and so on and a second group of transportation means of magnetic levitation trains or other high speed trains, airplanes, and so on) . The threshold speed may be defined by the network, or the threshold speed may be defined by the device (such as via a software application) . The threshold speed may be based on the difference in frequency between the frequency bands, the difference in bandwidths, whether the bands are time division duplex or frequency division duplex. In this manner, the threshold speed for switching between bands 3 and 30 may differ from the threshold speed for switching between

bands

3 and 39. In some implementations, the memory 445 may store a look up table or other index associating a threshold speed to each pair or group of frequency bands being observed for wireless coupling (such as a first threshold speed for

LTE frequency bands

3 and 39, a second threshold speed for LTE bands 30 and 39, etc. ) . The index may include association for frequency bands from other RATs, and the index is not limited to a specific implementation.

In some implementations, the threshold speed may be country (or other geographic boundary) specific. For example, a high speed train in Germany may move at a higher speed than a high speed train in the United States. In this manner, the threshold speed may be higher in Germany than in the United States to differentiate travelling on the high speed train from other forms of transportation. The index in the memory 445 may differentiate between countries (or other suitable geographies) in associating a threshold speed with the frequency bands being observed. While some example threshold speeds are provided, any suitable threshold speed may be used, and the present disclosure is not limited to the above examples.

In some other implementations of block 502 in Figure 5, the network may indicate to the device 400 that the speed is likely to be greater than the threshold speed. In some implementations, the network may indicate that the device 400 is coupled to a network for which the example methods are to be performed instead of indicating a specific threshold speed. In some implementations, a train system or other transit systems may be associated with a wireless network that is in addition to a typical telecommunication network outside of the transit system. For example, the high speed train system between Beijing and Jinan includes an LTE network that is in addition to the LTE and 5G networks outside of the high speed train system. Broadcasts or transmissions from the cells of the additional network may indicate that the device 400 is coupled to a network associated with a transit system (and thus the device 400 may move at a speed greater than the threshold speed) . For example, a serving cell of the high speed train’s LTE network between Beijing and Jinan may transmit to the UE a “highspeed” flag (which also may be referred to as a “highspeedtrain” flag) set to true ( “1” ) . The UE thus may be configured to use the highspeedtrain flag (or another suitable indicator from the network) to determine whether the UE may move faster than a threshold speed. In this manner, the network may not indicate a specific speed for measuring against a threshold speed, but instead indicate that the device is coupled to a network associated with UEs travelling at a high speed (such as indicating the UE is wirelessly coupled to a network for a high speed train, wirelessly coupled to a wireless network for a high speed highway, wirelessly coupled to a wireless network for an airplane, or other networks that may be associated with a high enough speed to cause the doppler effect to lower throughputs) . Any suitable means for determining whether the speed may be greater than a threshold speed may be used, and the present disclosure is not limited to a specific example for determining when the speed may be greater than a threshold speed.

If the speed may not be greater than the threshold speed (504) , the example method 500 may end, and the device 400 may operate as typical (such as not biasing toward coupling on a lower frequency band) . If the speed may be greater than the threshold speed, the device 400 may couple to a second device on a first frequency band that is a lower frequency than a second frequency band (506) . For example, an apparatus (such as the WCD 415 or another suitable device component or device) may include a processing system configured to determine whether the device 400 may be faster than a threshold speed. The apparatus also may include a first interface configured to output a request to couple the device 400 to the second device (such as a cell or base station) .

In some implementations, the device 400 may bias toward coupling on the first frequency band instead of the second frequency band. Referring back to the high speed train example, a subscriber identification module (SIM) card may be used to determine the Chinese mobile network for wireless communications, which may indicate that

bands

3, 39, and 41 may be coupled to for such wireless communications. A UE may bias toward coupling on band 3 instead of band 39 or band 41 based on receiving the highspeedtrain flag set to true (which may indicate that the user is travelling on the high speed train) . In the example implementation, the device 400 then may couple to another device on the first frequency band instead of on the second frequency band based on the biasing (510) . For example, a UE may be configured to bias toward handover from coupling on band 39 or band 41 to coupling on band 3 (such as switching cells) . In another example, the UE may be configured to bias toward remaining on band 3 instead of a handover to coupling on band 39 or band 41. In some other examples, different frequency bands other than

bands

3, 39, and 41 may be used, the device 400 may bias for switching between WLAN frequency bands or channels, or the device 400 may bias for switching between frequency bands across multiple RATs. The device 400 may couple to another device on a first frequency band if one or more conditions that are biased are satisfied.

LTE and 5G NR networks (as well as other 3GPP defined networks) may be configured to handover coupling of a UE between different cells as the UE travels through the geographic coverage areas of the cells. For example, if a UE 104 in Figure 1 travels through different geographic coverage areas 110 of base stations 102, the base stations 102 may hand over the wireless connection of the UE 104 between the appropriate base stations 102. If and when a UE 104 is to be handed over to a different base station 102 may be based on the UE 104 indicating that a handover is to occur. The UE 104 also may be configured to indicate the new cell and frequency band for handover. The UE 104 determining to switch frequency bands or cells may be based on one or more handover events. Handover events may be based on interference in the network, the number of UEs using a frequency band (thus affecting available network resources for the UE 104) , or other suitable factors.

In a WLAN, a STA may be configured to periodically measure the Received Signal Strength Indicator (RSSI) or Signal-to-Interference-plus-Noise Ratio (SINR) of the network. In a WWAN (such as an LTE or 5G NR network) , a UE may be configured to periodically measure the RSRP or the Reference Signals Received Quality (RSRQ) of a serving cell and neighboring cells.

For LTE and 5G NR networks, a UE may travel among a plurality of cells, and the network is configured to handover the wireless coupling between the different cells of the network. For example, the UE may be configured to select a cell for service based on RSRP or RSRQ measurements of a current serving cell or one or more neighboring cells from the UE, and the network may be configured to handle handover between cells based on a request from the UE. To note, if RSRP or RSRQ measurements are always communicated to the network by each UE, a plurality of UEs existing within a cell and neighboring cells may provide too many measurements to be processed by the network. Therefore, specific handover events may be defined to reduce the number of communications from UEs for managing handover of UEs.

3GPP defines a plurality of triggers (which also may be referred to as handover events) when the UE may provide measurements or request, to the serving cell or a candidate cell, a handover. For example, handover events A1-A6 are defined by 3GPP. A1 is defined as the serving cell’s measured RSRP or RSRQ becoming better than a threshold (which may indicate that the current link quality is increasing) . A2 is defined as the serving cell’s measured RSRP or RSRQ becoming worse than a threshold (which may indicate that the current link quality is decreasing) . A3 is defined as a neighbor cell’s RSRP or RSRQ becoming better than the primary serving cell’s RSRP or RSRQ by at least a defined offset between the measurements. A4 is defined as a neighbor cell’s RSRP or RSRQ becoming better than a threshold. A5 is defined as the primary serving cell’s RSRP or RSRQ becoming worse than a first threshold and a neighbor cell’s RSRP or RSRQ becoming better than a second threshold (which may be the same or different than the first threshold) . A6 is defined as the neighbor cell’s RSRP or RSRQ becoming better than a secondary serving cell’s RSRP or RSRQ by a defined offset between the measurements. Other reporting triggers are defined by 3GPP, including events C1 and C2, B1 and B2, W1 –W3, and V1 and V2, which may trigger the UE to report LTE measurements to the network (or otherwise request a handover) .

The network may adjust one or more triggers or transmit other rules for handover to the UE to assist the UE in selecting the cell for service or determining when to report measurements or otherwise request a handover. For example, the network may define (and indicate to the UE) the offsets for events A3 and A6 or the thresholds for events A1, A2, A4, and A5. The network also may prohibit handovers between specific cells or otherwise define the handover between cells.

In some implementations of biasing A3 events, the UE may adjust the A3 offset defined by the network. For example, an RSRP (or RSRQ) of a neighbor cell may be higher than an RSRP (or RSRQ) of the serving cell by at least a defined amount to satisfy the A3 event. The UE may increase or decrease the defined amount so that the RSRP (or RSRQ) of the neighbor cell is greater than the RSRP (or RSRQ) of the serving cell by the increased or decreased amount to satisfy the A3 event. If the UE is wirelessly coupled to the network on a first frequency band that is a lower frequency than a second frequency band that may be used after handover, the UE may increase the offset, such as defined in equation (1) below:

Biased A3 Offset=A3 Offset+A3 Offset Bias (1)

where the A3 Offset Bias is greater than or equal to zero. In one example, the A3 Offset Bias may be 20 dBm when measuring RSRP for the cells. However, any suitable bias may be used. In some implementations, the bias value may be based on the difference in frequency between the first frequency band and the second frequency band. In some other implementations, the bias value may be based on current throughput, bandwidths of the channels, or other quality metrics. In some further implementations, the bias may be a suitable, static value. In this manner, the A3 event is more difficult to satisfy when the UE is coupled on a lower frequency band than on a higher candidate frequency band. For example, if a UE is coupled to the network on band 3, the A3 event may be more difficult to satisfy for handover to band 39 or 41 because of the biased A3 offset.

If the UE is wirelessly coupled to the network on a second frequency band that is a higher frequency than a first frequency band that may be used after handover, the UE may decrease the offset, such as defined in equation (2) below:

Biased A3 Offset=A3 Offset-A3 Offset Bias (2)

where the A3 Offset Bias is greater than or equal to zero. In some implementations, the A3 Offset Bias may be the same for equations 1 and 2. In some other implementations, the A3 Offset Bias may differ between equation 1 and equation 2. Any suitable bias (such as 20 dBm or another suitable static value, a dynamic value based on the difference in frequency of the bands or signal quality metrics, etc. ) may be used. In this manner, the A3 event is easier to satisfy when the UE is coupled on a higher frequency band than on a lower candidate frequency band. For example, if a UE is coupled to the network on band 39, the A3 event may be easier to satisfy for handover to band 3 because of the biased A3 offset.

In some implementations of biasing for A4 events, the UE may adjust the A4 threshold (which may be defined by the network) . For example, an RSRP (or RSRQ) of a neighbor cell may be higher than the A4 threshold. The UE may increase or decrease the threshold to cause the A4 event to be easier or more difficult to satisfy based on if the current frequency band is a lower frequency or a higher frequency than a candidate frequency band. If the UE is wirelessly coupled to the network on a first frequency band that is a lower frequency than a second frequency band that may be used after handover, the UE may increase the threshold, such as defined in equation (3) below:

Biased A4 Threshold=A4 Threshold+A4 Threshold Bias (3)

where the A4 Threshold Bias is greater than or equal to zero. In one example, the A4 Threshold Bias may be 40 dBm when measuring RSRP for the cells. However, any suitable bias may be used. In some implementations, the bias value may be based on the difference in frequency between the first frequency band and the second frequency band. In some other implementations, the bias value may be based on current throughput, channel bandwidths, or other quality metrics. In some further implementations, the bias may be a static value. In this manner, the A4 event is more difficult to satisfy when the UE is coupled on a lower frequency band than on a higher candidate frequency band. For example, if a UE is coupled to the network on band 3, the A4 event may be more difficult to satisfy for handover to band 39 or 41 because of the biased A4 threshold.

If the UE is wirelessly coupled to the network on a second frequency band that is a higher frequency than a first frequency band that may be used after handover, the UE may decrease the threshold, such as defined in equation (4) below:

Biased A4 Threshold=A4 Threshold-A4 Threshold Bias (4)

where the A4 Threshold Bias is greater than or equal to zero. In some implementations, the A4 Threshold Bias may be the same for equations 3 and 4. In some other implementations, the A4 Threshold Bias may differ between equation 3 and equation 4. Any suitable bias (such as 40 dBm or another suitable static value, a dynamic value based on the difference in frequency of the bands or signal quality metrics, etc. ) may be used. In this manner, the A4 event is easier to satisfy when the UE is coupled on a higher frequency band than on a lower candidate frequency band. For example, if a UE is coupled to the network on band 39, the A4 event may be easier to satisfy for handover to band 3 because of the biased A4 event threshold. In some implementations, when the handover event is satisfied (whether or not the device biases for the event) , handover may occur to the new frequency band. In this manner, the device may not be prevented from switching frequency bands, but the device may set a preference from the frequency bands.

Determining whether a first frequency band is a lower frequency band than a second frequency band may be based on any suitable factor. For example, the determination may be based on the frequency for DL traffic, the frequency for UL traffic, or the median or average frequency for UL traffic and DL traffic of the frequency band. In some implementations, determining whether a frequency band is lower than another frequency band may be based on the bandwidth of the bands being within a threshold of one another, the channel sizes of the frequency bands, the band being FDD bands or TDD bands, etc.

In some implementations, determining whether to bias toward coupling on a first frequency band (such as adjusting the A3 event offset or the A4 event threshold) , may be based on whether the frequency band to be biased toward for coupling has an RSRP or an RSRQ above a reference signal threshold (indicating a sufficient power or quality of the medium for coupling) . For example, if the first frequency band is a lower frequency band than a second frequency band, biasing to switch to the first frequency band (if not currently on the first frequency band) or remain on the first frequency band (if currently on the first frequency band) may be based on whether the RSRP or RSRQ of the first frequency band is greater than a reference signal threshold. If the RSRP or RSRQ of the first frequency band is greater than the threshold, the device 400 may be configured to bias toward the first frequency band. If the RSRP or RSRQ of the first frequency band is less than the threshold, the device 400 may be configured to prevent biasing toward the first frequency band. In some implementations, the RSRP or RSRQ is determined only for the current serving cell’s frequency band. In some other implementations, the RSRP or RSRQ is determined for either the current serving cell’s frequency band or a candidate frequency band (such as of a neighbor cell) .

As noted above, an FDD band may be associated with a higher throughput than a TDD band based on the TDD band sharing the same frequencies for UL and DL traffic while the FDD band includes separate frequencies for UL traffic and DL traffic. For example, the frequency for DL traffic on band 3 is centered at approximately 1842.5 MHz, and the frequency for UL traffic on band 3 is centered at approximately 1747.5 MHz, allowing for concurrent UL and DL transmissions. The frequency for DL traffic and UL traffic on band 39 is centered at approximately 1900 MHz, and UL and DL transmissions must occur at different times. In some implementations, a device may be configured to couple on an FDD band instead of a TDD band. For example, a UE may be configured to bias toward coupling on an FDD band (such as band 3) instead of a TDD band (such as band 39 or band 41) .

Figure 6 is a flowchart of an example method 600 of wireless coupling on an FDD band instead of a TDD band. At 602, a device 400 may determine whether a first frequency band is an FDD band, and at 604, the device 400 may determine whether a second frequency band is a TDD band. If the first frequency band is not an FDD band or the second frequency band is not a TDD band (such as the first frequency band and the second frequency band both being FDD bands or TDD bands) , the method 600 may end. For example, the device 400 may not bias toward coupling on the first frequency band instead of on the second frequency band, such as a UE not biasing for coupling on band 39 or for coupling on band 41 since both bands are TDD bands.

If the first frequency band is an FDD band and the second frequency band is a TDD band, the device 400 may couple to another device on the first frequency band instead of the second frequency band (606) . For example, if the first frequency band is band 3 (which is an FDD band) and the second frequency band is band 39 (which is a TDD band) , a UE may couple to a cell on band 3 instead of band 39. In some implementations, the device 400 may bias toward coupling on the FDD band instead of the TDD band (608) . Biasing may be performed in any suitable manner, such as described above with reference to Figure 5. For example, a UE may adjust the A3 event offset or the A4 event threshold. Examples of biasing for A3 or A4 events may be as defined in equations (1) – (4) , except the biasing is toward an FDD band as compared to biasing toward a lower frequency band, as described above. Any suitable form of biasing may be performed, though, and the disclosure is not limited to biasing A3 or A4 events. Referring back to Figure 6 for the implementation of biasing, the device 400 may couple to another device on the first frequency band instead of the second frequency band based on the biasing (610) . For example, the bias may make satisfying an A3 event or A4 event more difficult so that a UE will remain on an FDD band, or the bias may cause satisfying an A3 event or an A4 event to be easier so that a UE will switch from a TDD band to an FDD band.

The device 400 may include an index of frequency bands identifying each band as an FDD band or a TDD band, which may be as defined in a standard (such as for LTE bands or for NR bands) . In some implementations, a device 400 may store in memory 445 an index or mapping of frequency bands to traits (such as a frequency for the band, whether the band is an FDD band, whether the band is a TDD band, etc. ) The device 400 may be configured to use the index or mapping to determine whether to bias. In some other implementations, biasing (and other operations related to biasing) may be performed in hardware (such as a dedicated circuit or other logic programmed to perform the operations) . In some other implementations, biasing (and other operations related to biasing) may be performed in software or a combination of hardware and software.

If a plurality of UEs are on band 3 and no UEs are on band 39, the throughput on band 39 may be greater than the throughput on band 3 because more network resources may be available on band 39 than on band 3. In some implementations, a device 400 may be configured to base biasing on load balancing or balancing of available resources of the frequency bands. For example, a UE may be configured to determine if or how to bias handover events (such as when or the amount to adjust an A3 Event Offset or an A4 Event Threshold) based on an existing load on one or more of the first frequency band or the second frequency band.

In some implementations of determining a load on a frequency band, the device 400 may be configured to observe communications on the frequency band. For example, in a WLAN, a STA may measure a number of contentions, time the medium is busy, or other metrics in observing the wireless medium. In a WWAN (such as an LTE network) , a UE may measure scheduling grants to the UE on the current frequency band. The scheduling grants may indicate a load on the frequency band. The scheduling grants also may indicate link quality information for the UE (which may depend on the network’s scheduler type) . For example, if the network’s scheduler implements a round robin scheduling algorithm, a larger number of total grants to the UE over time may indicate fewer UEs on the frequency band than a smaller number of total grants to the UE over time. If the network’s scheduler takes into consideration quality of service (QoS) information or frequency band quality information (such as QoS Class Identifier (QCI) provided by the UE, SINR, etc. ) , a smaller number of total grants to the UE over time may indicate a lower link quality on the frequency band than a larger number of total grants to the UE over time. For example, each UE may provide a reference signal to the cell every millisecond. The cell may use the reference signals to determine quality metrics for the frequency band and UEs, and the quality metrics may affect scheduling for the UEs on the frequency band. Scheduling also may be affected by data priority. For example, voice over internet protocol (VoIP) traffic may have a higher priority that best effort (BE) data traffic, and a UE to send or receive VoIP traffic may be prioritized in scheduling by the network over a UE to send or receive BE data traffic. In this manner, a reduced number of scheduling grants to a UE may indicate that fewer network resources are available to the UE on the frequency band.

In some implementations, a UE may determine a scheduling rate in observing the wireless medium. A scheduling rate may indicate a number of scheduling grants to the UE over time, such as defined in equation (5) below:

where “number of total grants” is the observed number of total grants from the cell to the UE and “total time” is the amount of time during which the UE observes the number of total grants to the UE. In some implementations, the number of total grants may be measured as the amount of time the UE is granted access to the frequency band. For example, grants may be at the subframe level of an LTE network, with each subframe being 1 millisecond (ms) . The number of total grants may indicate the number of subframes granted to the UE in terms of milliseconds. The total time may indicate the total number of subframes that have passed in terms of milliseconds. In this manner, the unit of the scheduling rate may be a percentage of the total time.

The grants may be based on UL traffic, DL traffic, or both. For example, for an FDD band, the UE may observe grants to the UL portion of the FDD band. In another example, the UE may observe when the DL portion of the FDD band includes traffic for the UE. In a further example, for a TDD band, the UE may observe when the UE is granted access to the TDD band for UL traffic and DL traffic. However, any suitable means for observing grants to the UE may be performed.

Figure 7 is a flowchart of an example method 700 of determining a scheduling rate to a UE. At 702, a value n is set to one and a value p is set to zero. n may be a count of the total number of subframes observed, and p may be a count of the subframes granted to the UE in determining the scheduling rate. In the example, the scheduling rate may be p divided by n. At 704, the UE may determine if a subframe n is granted to the UE by the scheduler (such as by observing the grants from the cell to the UE) . If subframe n is granted to the UE (706) , the UE may increment p (708) . If subframe n is not granted to the UE, the method 700 may skip block 708 (with the UE not incrementing p) .

At 710, the UE may determine the scheduling rate. For example, the UE may determine the scheduling rate as p divided by n. The scheduling rate may be a percentage (or any other suitable unit of measurement) . The UE may be configured to determine when or how to bias based on the scheduling rate. In some implementations, if the UE is to bias to a lower frequency band, the UE may determine whether to bias toward the lower frequency band (or prevent biasing) based on whether the scheduling rate is greater than a threshold rate. For example, if the current serving cell is on a first frequency band that is a lower frequency than a second frequency band, the UE may bias towards the first frequency band if the scheduling rate is greater than a threshold rate. In contrast, the UE may prevent biasing towards the first frequency band if the scheduling rate is less than the threshold rate. If the current serving cell is on a second frequency band that is a higher frequency than a first frequency band, the UE may bias towards the first frequency band if the scheduling rate is less than a threshold rate. In some implementations, the UE may prevent biasing towards the first frequency band if the scheduling rate is greater than the threshold rate.

In some other implementations, if the UE is to bias toward an FDD band instead of a TDD band, the UE may determine whether to bias toward the FDD band (or prevent biasing) based on whether the scheduling rate is greater than a threshold rate. For example, if the current serving cell is on an FDD band and a second frequency band is a TDD band, the UE may bias towards the first frequency band if the scheduling rate is greater than a threshold rate. In contrast, the UE may prevent biasing towards the first frequency band if the scheduling rate is less than the threshold rate. If the current serving cell is on a second frequency band that is a TDD band and a first frequency band is an FDD band, the UE may bias towards the first frequency band if the scheduling rate is less than a threshold rate. In some implementations, the UE may prevent biasing towards the first frequency band if the scheduling rate is greater than the threshold rate. The UE also may adjust the amount of bias based on the scheduling rate. For example, the amount of bias may be increased or decreased based on a difference in the scheduling rate and the threshold rate. In this manner, load balancing may be considered in a UE’s determination of whether and how to bias toward a frequency band. The threshold rate may be any suitable threshold. For example, the threshold may be defined by the network, the UE, or a combination of both, and the threshold may be static or dynamic.

Referring back to Figure 7, if the scheduling rate is less than the threshold rate (712) , the scheduling rate may be reset. For example, the method 700 may revert to block 702, and n and p may be reset to one and zero, respectively, in determining the scheduling rate. In this manner, the next subframe observed is considered the first subframe for the total time in determining the scheduling rate. If the scheduling rate is not less than the threshold rate, the UE may still reset the scheduling rate if the cell is switched (714) . Since the old scheduling rate does not apply after cell switching, the scheduling rate may be reset by the method 700 reverting to block 702, and n and p may be reset to one and zero, respectively, in determining the scheduling rate. If neither the scheduling rate is less than the threshold rate (712) nor the cell is switched (714) , n may be incremented (716) . The method 700 then may revert to block 704 to determine if the next subframe is granted to the UE. In this manner, the scheduling rate is an average over time while the scheduling rate is greater than the threshold rate and the UE does not switch from the cell.

Referring back to decision block 712, in some implementations, decision block 712 is applied if the first frequency band on which the UE is coupled to the network is a lower frequency than a second frequency band (if the UE is to bias toward lower frequency bands) , or decision block 712 is applied if the first frequency band on which the UE is coupled to the network is an FDD band and a second frequency band is a TDD band (is the UE is to bias toward FDD bands) . If the UE is coupled on the second frequency band in the above examples, the UE may not reset the scheduling rate (as illustrated in Figure 7) . For example, the UE may reset the scheduling rate if the scheduling rate goes above the threshold rate.

If the scheduling rate is determined over time, decisions to bias based on the scheduling rate may be insulated from short instances of a scheduling rate being above (or below) the threshold rate. For example, a time of no grants on the frequency band surrounded by times of frequent grants on the frequency band may not cause the UE to prevent biasing toward a current servicing frequency band (as the scheduling rate may still average above the threshold rate) .

Referring back to Figure 7, each subframe may be 1 ms. In this manner, the UE may update the scheduling rate every millisecond. However, the UE may update the scheduling rate at any suitable period or frequency.

As noted above, in the high speed train example in China, UEs may switch between

frequency bands

3, 39, and 41. Many UEs attempt to couple to the network on the highest band (such as

bands

39 or 41 instead of band 3) . As a result, most UEs may attempt to couple to the network on a TDD band at a higher frequency than an available FDD band. As described herein, doppler effect may lower throughput on

bands

39 and 41 to less than what can be achieved on band 3 (because band 3 is a lower frequency and an FDD band as compared to bands 39 and 41) . In some implementations, a UE may be configured to bias toward coupling on an FDD band that is a lower frequency than the TDD bands if the UE may move at a high rate of speed (such as the cell indicating the network is for a high speed train) . The UE also may be configured to base the biasing on a scheduling rate to help increase the throughput to be achieved.

Figure 8 is a flowchart of an example method 800 of biasing wireless coupling on a high speed train network. While the example method 800 is illustrated as regarding the

frequency bands

3, 39, and 41, any suitable frequency bands of different frequencies or different FDD and TDD bands may be used. For example, the method may apply to other frequency bands defined by 3GPP for LTE networks or 5G NR networks in China, Europe, India, North America, or anywhere else in the world. Additionally, while the example method 800 is illustrated as regarding a network for a high speed train, any suitable network may be used. For example, other devices for other WLAN or WWAN may use the techniques for biasing toward specific frequency bands.

At decision block 802, the UE may determine if a HighSpeed flag set to true ( “1” ) is received from the network. For example, the UE may be coupled to a cell on a first frequency band with a candidate second frequency band existing. If the network is not for a high speed train system (such as the high speed train between Beijing and Jinan) , the network may not be configured to provide a highspeed flag, or the highspeed flag may be set to false ( “0” ) . In this manner, the UE may not receive the highspeed flag set to true to indicate that the UE may move at a high speed. As a result, the method 800 may end, and the UE may determine not to bias toward an FDD band or a lower frequency band. For example, the UE may prevent adjusting the A3 event offset or A4 event threshold to bias toward coupling on an FDD band or a lower frequency band.

If the UE receives the highspeed flag set to true (802) , the UE may determine the scheduling rate (804) . The UE also may determine the RSRP of the serving cell on the first frequency band on which the UE is coupled (806) . If the first frequency band on which the UE is coupled is band 3 (808) , the UE is coupled on an FDD band that is a lower frequency than bands 39 and 41 (which are TDD bands) . Therefore, if the second (candidate) frequency band is band 39 or band 41 (810) , the RSRP of band 3 is greater than an RSRP threshold (812) , and the scheduling rate is greater than a rate threshold (814) , the UE may increase the A3 event offset by an offset bias (816) , and the UE may increase the A4 event threshold by a threshold bias (818) .

In one example, the RSRP threshold for band 3 may be -105 dBm. However, any suitable RSRP threshold value may be used. In some other implementations, the UE may be configured to measure RSRQ and compare to an RSRQ threshold. An example rate threshold for comparing the scheduling rate may be ten percent, an example A3 event offset bias may be 20 dBm, and an example A4 event threshold bias may be 40 dBm. However, other suitable biases and thresholds may be used. In some other implementations, the A3 event offset or the A4 event threshold may be changed to a defined value based on the parameters in decision blocks 808 –814 being met. For example, an index of different offsets or thresholds may be stored in a memory 445 (Figure 4A) of the UE, and the UE may be configured to lookup the offset or the threshold based on the parameters.

Referring back to decision blocks 810 –814, if the second frequency band is not band 39 or band 41 (810) , the RSRP is less than the RSRP threshold (812) , or the scheduling rate is less than the rate threshold (814) , the method 800 may end, and the UE may not bias toward frequency band 3. Referring back to decision block 808, if the first frequency band is not band 3, the UE may be coupled to the network on band 39 or band 41, which may be a TDD band that is a higher frequency than band 3. If the second (candidate) frequency band is band 3 (820) and the scheduling rate is less than the rate threshold (822) , the UE may decrease the A3 event offset by an offset bias (824) , and the UE may decrease the A4 event threshold by a threshold bias (826) . The biases may be the same as used in

blocks

816 and 818. In some other implementations, the biases for decreasing the A3 event offset and the A4 event threshold may differ from the biases when increasing the A3 event offset and the A4 event threshold.

In some implementations, the UE also may measure the RSRP (or RSRQ) of the second frequency band. For example, the UE may be coupled to the cell on band 39 or band 41 (which is a TDD band) , and the UE may be configured to measure the RSRP or RSRQ of band 3 (which is an FDD band of a lower frequency than band 39 or band 41) . The UE may be configured to compare the RSRP or RSRQ of the second frequency band to a reference signal threshold (such as -105 dBm or other suitable value) . In this manner, decreasing the A3 event offset (824) and decreasing the A4 event offset (826) also may be based on the RSRP or the RSRQ of the second frequency band being greater than the reference signal threshold.

As noted above, the biases may be static or dynamic. For example, the biases may be based on a difference between a scheduling rate and a rate threshold. The biases also may be based on a difference between the RSRP and the RSRP threshold (or an RSRQ and an RSRQ threshold) .

Referring back to decision block 820, if the second frequency band is not band 3 (such as the second frequency band being band 39 or band 41 and the first frequency band being the other of band 39 and band 41) , the example method 800 may end, and the UE may not bias toward the first frequency band or toward the second frequency band (such as if the frequency bands are both TDD bands or are both FDD bands) . Referring back to decision block 822, if the scheduling rate is greater than the rate threshold, the example method 800 may end, and the UE may not bias toward the first frequency band or toward the second frequency band. The rate threshold in decision block 822 may be the same or different than the rate threshold in decision block 814. To note, any suitable rate threshold may be used in performing aspects of the disclosure. As shown in describing example method 800, a UE may bias toward a lower frequency, FDD band 3 over

TDD bands

39 and 41 to increase throughput when on a high speed train network. However, as described above, aspects of the disclosure may be used outside of a network for a high speed train, may be used for different RATs, and may be used for different frequency bands.

It is understood that the specific order or hierarchy of blocks in the processes /flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, where reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

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.

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.

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.

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 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.

Claims

A method of wireless communication, comprising:

determining, by a first device, whether a speed of the first device may be greater than a threshold speed; and

coupling, by the first device, to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed, wherein the first frequency band is a lower frequency than the second frequency band.
The method of claim 1, further comprising biasing toward coupling on the first frequency band instead of the second frequency band in response to determining that the speed of the first device may be greater than the threshold speed, wherein coupling to the second device on the first frequency band is based on the biasing.
The method of claim 2, wherein the first device is a user equipment (UE) and the second device is a cell.
The method of claim 3, wherein the first frequency band is a frequency division duplex (FDD) band and the second frequency band is a time division duplex (TDD) band.
The method of claim 4, wherein biasing toward coupling on the first frequency band includes adjusting one or more handover events.
The method of claim 5, wherein adjusting the one or more handover events includes at least one from the group consisting of:

adjusting an A3 event offset; and

adjusting an A4 event threshold.
The method of claim 6, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The method of claim 7, further comprising:

observing, by the UE, scheduling grants on the first frequency band, wherein biasing towards the first frequency band is based on the observed scheduling grants.
The method of claim 8, further comprising:

determining a scheduling rate of the UE on the first frequency band;

comparing the scheduling rate to a threshold rate; and

preventing the UE from biasing toward the first frequency band based on the scheduling rate being less than the threshold rate.
The method of claim 9, further comprising:

updating the scheduling rate every millisecond; and

resetting the scheduling rate in response to the UE switching cells or the scheduling rate being less than the threshold rate.
The method of claim 9, further comprising:

determining, by the UE, a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

comparing the RSRP or the RSRQ to a reference signal threshold; and

preventing the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The method of claim 6, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
The method of claim 12, further comprising:

determining a scheduling rate of the UE on the second frequency band;

comparing the scheduling rate to a threshold rate; and

preventing the UE from biasing toward the first frequency band based on the scheduling rate being greater than the threshold rate.
The method of claim 13, further comprising:

determining, by the UE, a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

comparing the RSRP or the RSRQ to a reference signal threshold; and

preventing the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The method of claim 6, wherein determining that the speed of the UE may be greater than the threshold speed includes receiving, by the UE from the cell, a highspeed flag set to true to indicate that the cell is from a high speed train wireless network.
The method of claim 15, wherein the first frequency band is band 3 and the second frequency band is band 39 or band 41 for a Long Term Evolution (LTE) network.
An apparatus for wireless communication, comprising:

a processing system configured to cause a first device to determine whether a speed of a first device may be greater than a threshold speed; and

a first interface configured to output a request to couple the first device to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed, wherein the first frequency band is a lower frequency than the second frequency band.
The apparatus of claim 17, wherein:

the processing system is further configured to bias toward coupling on the first frequency band instead of the second frequency band in response to determining that the speed of the first device may be greater than the threshold speed; and

the first interface is configured to output the request to couple the first device to the second device on the first frequency band based on the biasing.
The apparatus of claim 18, wherein the first device is a user equipment (UE) and the second device is a cell.
The apparatus of claim 19, wherein the first frequency band is a frequency division duplex (FDD) band and the second frequency band is a time division duplex (TDD) band.
The apparatus of claim 20, wherein the processing system is further configured to adjust one or more handover events in biasing toward coupling on the first frequency band.
The apparatus of claim 21, wherein the processing system is configured to adjust the one or more handover events by perform at least one from the group consisting of:

adjusting an A3 event offset; and

adjusting an A4 event threshold.
The apparatus of claim 22, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The apparatus of claim 23, wherein the processing system is further configured to observe scheduling grants for the UE on the first frequency band, wherein biasing towards the first frequency band is based on the observed scheduling grants.
The apparatus of claim 24, wherein the processing system is further configured to:

determine a scheduling rate of the UE on the first frequency band;

compare the scheduling rate to a threshold rate; and

prevent the UE from biasing toward the first frequency band based on the scheduling rate being less than the threshold rate.
The apparatus of claim 25, wherein the processing system is further configured to:

update the scheduling rate every millisecond; and

reset the scheduling rate in response to the UE switching cells or the scheduling rate being less than the threshold rate.
The apparatus of claim 25, wherein the processing system is further configured to:

determine a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

compare the RSRP or the RSRQ to a reference signal threshold; and

prevent the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The apparatus of claim 22, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
The apparatus of claim 28, wherein the processing system is further configured to:

determine a scheduling rate of the UE on the second frequency band;

compare the scheduling rate to a threshold rate; and

prevent the UE from biasing toward the first frequency band based on the scheduling rate being greater than the threshold rate.
The apparatus of claim 29, wherein the processing system is further configured to:

determine a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

compare the RSRP or the RSRQ to a reference signal threshold; and

prevent the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The apparatus of claim 23, wherein determining that the speed of the UE may be greater than the threshold speed includes receiving, by the UE from the cell, a highspeed flag set to true to indicate that the cell is from a high speed train wireless network.
The apparatus of claim 31, wherein the first frequency band is band 3 and the second frequency band is band 39 or band 41 for a Long Term Evolution (LTE) network.
A non-transitory, computer-readable medium storing instructions that, when executed by a processor of a first device, cause the first device to:

determine whether a speed of the first device may be greater than a threshold speed;

couple, by the first device, to a second device on a first frequency band instead of a second frequency band based on determining that the speed of the first device may be greater than the threshold speed, wherein the first frequency band is a lower frequency than the second frequency band.
The computer-readable medium of claim 33, wherein execution of the instructions further cause the first device to bias toward coupling to the second device on the first frequency band instead of the second frequency band in response to determining that the speed of the first device may be greater than the threshold speed.
The computer-readable medium of claim 34, wherein the first device is a user equipment (UE) and the second device is a cell.
The computer-readable medium of claim 35, wherein the first frequency band is a frequency division duplex (FDD) band and the second frequency band is a time division duplex (TDD) band.
The computer-readable medium of claim 36, wherein execution of the instructions further cause the first device to adjust one or more handover events in biasing toward coupling on the first frequency band.
The computer-readable medium of claim 37, wherein execution of the instructions further cause the first device to, in adjusting the one or more handover events, perform at least one from the group consisting of:

adjusting an A3 event offset; and

adjusting an A4 event threshold.
The computer-readable medium of claim 38, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The computer-readable medium of claim 39, wherein execution of the instructions further cause the first device to observe scheduling grants on the first frequency band, wherein biasing towards the first frequency band is based on the observed scheduling grants.
The computer-readable medium of claim 40, wherein execution of the instructions further cause the first device to:

determine a scheduling rate of the UE on the first frequency band;

compare the scheduling rate to a threshold rate; and

prevent the UE from biasing toward the first frequency band based on the scheduling rate being less than the threshold rate.
The computer-readable medium of claim 41, wherein execution of the instructions further cause the first device to:

update the scheduling rate every millisecond; and

reset the scheduling rate in response to the UE switching cells or the scheduling rate being less than the threshold rate.
The computer-readable medium of claim 41, wherein execution of the instructions further cause the first device to:

determine a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

compare the RSRP or the RSRQ to a reference signal threshold; and

prevent the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The computer-readable medium of claim 38, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
The computer-readable medium of claim 44, wherein execution of the instructions further cause the first device to:

determine a scheduling rate of the UE on the second frequency band;

compare the scheduling rate to a threshold rate; and

prevent the UE from biasing toward the first frequency band based on the scheduling rate being greater than the threshold rate.
The computer-readable medium of claim 45, wherein execution of the instructions further cause the first device to:

determine a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

compare the RSRP or the RSRQ to a reference signal threshold; and

prevent the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The computer-readable medium of claim 38, wherein determining that the speed of the UE may be greater than the threshold speed includes receiving, by the UE from the cell, a highspeed flag set to true to indicate that the cell is from a high speed train wireless network.
The computer-readable medium of claim 47, wherein the first frequency band is band 3 and the second frequency band is band 39 or band 41 for a Long Term Evolution (LTE) network.
An apparatus for wireless communication, comprising:

means for determining whether a speed of the apparatus may be greater than a threshold speed; and

means for coupling to a device on a first frequency band instead of a second frequency band based on determining that the speed of the apparatus may be greater than the threshold speed, wherein the first frequency band is a lower frequency than the second frequency band.
The apparatus of claim 49, further comprising means for biasing toward coupling to the device on the first frequency band instead of the second frequency band in response to determining that the speed of the apparatus may be greater than the threshold speed, wherein coupling to the device on the first frequency band is based on the biasing.
The apparatus of claim 50, wherein the apparatus is a user equipment (UE) and the device is a cell.
The apparatus of claim 51, wherein the first frequency band is a frequency division duplex (FDD) band and the second frequency band is a time division duplex (TDD) band.
The apparatus of claim 52, further comprising means for adjusting one or more handover events in biasing toward coupling on the first frequency band.
The apparatus of claim 53, wherein adjusting the one or more handover events includes at least one from the group consisting of:

adjusting an A3 event offset; and

adjusting an A4 event threshold.
The apparatus of claim 54, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The apparatus of claim 55, further comprising:

means for observing scheduling grants on the first frequency band, wherein biasing towards the first frequency band is based on the observed scheduling grants.
The apparatus of claim 56, further comprising:

means for determining a scheduling rate of the UE on the first frequency band;

means for comparing the scheduling rate to a threshold rate; and

means for preventing the UE from biasing toward the first frequency band based on the scheduling rate being less than the threshold rate.
The apparatus of claim 57, further comprising:

means for updating the scheduling rate every millisecond; and

means for resetting the scheduling rate in response to the UE switching cells or the scheduling rate being less than the threshold rate.
The apparatus of claim 57, further comprising:

means for determining a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

means for comparing the RSRP or the RSRQ to a reference signal threshold; and

means for preventing the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The apparatus of claim 54, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
The apparatus of claim 60, further comprising:

means for determining a scheduling rate of the UE on the second frequency band;

means for comparing the scheduling rate to a threshold rate; and

means for preventing the UE from biasing toward the first frequency band based on the scheduling rate being greater than the threshold rate.
The apparatus of claim 57, further comprising:

means for determining a reference signal receive power (RSRP) or a reference signal receive quality (RSRQ) of the first frequency band;

means for comparing the RSRP or the RSRQ to a reference signal threshold; and

means for preventing the UE from biasing toward the first frequency band based on the RSRP or the RSRQ being less than the reference signal threshold.
The apparatus of claim 54, wherein determining that the speed of the UE may be greater than the threshold speed includes receiving, by the UE from the cell, a highspeed flag set to true to indicate that the cell is from a high speed train wireless network.
The apparatus of claim 63, wherein the first frequency band is band 3 and the second frequency band is band 39 or band 41 for a Long Term Evolution (LTE) network.
A method of wireless communication, comprising:

coupling, by a first device, to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex (FDD) band and the second frequency band being a time division duplex (TDD) band.
The method of claim 65, further comprising biasing, by the first device, toward coupling to the second device on the first frequency band instead of the second frequency band based on the first frequency band being a FDD band and the second frequency band being a TDD band, wherein coupling to the second device on the first frequency band is based on the biasing.
The method of claim 66, wherein biasing toward coupling on the first frequency band includes:

adjusting an A3 event offset of an A3 handover event; and

adjusting an A4 event threshold of an A4 handover event, wherein the first device is a user equipment (UE) and the second device is a cell.
The method of claim 67, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The method of claim 68, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
An apparatus for wireless communication, comprising:

a processing system configured to determine to couple a first device to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex (FDD) band and the second frequency band being a time division duplex (TDD) band; and

a first interface configured to output a request to couple the first device to the second device on the first frequency band based on the determination.
The apparatus of claim 70, wherein:

the processing system is further configured to bias coupling the first device to the second device on the first frequency band instead of the second frequency band based on the first frequency band being an FDD band and the second frequency band being a TDD band; and

the first interface is configured to output the request based on the biasing.
The apparatus of claim 71, wherein the processing system is further configured, in biasing toward coupling on the first frequency band, to:

adjust an A3 event offset of an A3 handover event; and

adjust an A4 event threshold of an A4 handover event, wherein the first device is a user equipment (UE) and the second device is a cell.
The apparatus of claim 72, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The apparatus of claim 72, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
A non-transitory, computer-readable medium storing instructions that, when executed by a processor of a first device, cause the first device to:

couple to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex (FDD) band and the second frequency band being a time division duplex (TDD) band.
The computer-readable medium of claim 75, wherein execution of the instructions further cause the first device to bias toward coupling to the second device on the first frequency band instead of the second frequency band based on the first frequency band being an FDD band and the second frequency band being a TDD band, wherein coupling to the second device on the first frequency band is based on the biasing.
The computer-readable medium of claim 76, wherein execution of the instructions further cause the first device, in biasing toward coupling on the first frequency band, to:

adjust an A3 event offset of an A3 handover event; and

adjust an A4 event threshold of an A4 handover event, wherein the first device is a user equipment (UE) and the second device is a cell.
The computer-readable medium of claim 77, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The computer-readable medium of claim 77, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
An apparatus for wireless communication, comprising:

means for coupling to a second device on a first frequency band instead of a second frequency band based on the first frequency band being a frequency division duplex (FDD) band and the second frequency band being a time division duplex (TDD) band.
The apparatus of claim 80, further comprising means for biasing toward coupling to the second device on the first frequency band instead of the second frequency band based on the first frequency band being an FDD band and the second frequency band being a TDD band, wherein coupling to the second device on the first frequency band is based on the biasing.
The apparatus of claim 81, further comprising:

means for adjusting an A3 event offset of an A3 handover event; and

means for adjusting an A4 event threshold of an A4 handover event, wherein the apparatus is a user equipment (UE) and the second device is a cell.
The apparatus of claim 82, wherein:

the UE is coupled to the cell on the first frequency band;

adjusting the A3 event offset includes increasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes increasing the A4 event threshold by a threshold bias.
The apparatus of claim 82, wherein:

the UE is coupled to the cell on the second frequency band;

adjusting the A3 event offset includes decreasing the A3 event offset by an offset bias; and

adjusting the A4 event threshold includes decreasing the A4 event threshold by a threshold bias.
A method of wireless communication, comprising:

receiving, by a user equipment (UE) , an indicator from a cell of a network that the network is a high speed train network, wherein the cell is coupled to the UE on a first frequency band;

determining a scheduling rate of the UE on the first frequency band; and

when the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band:

measuring a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the first frequency band;

in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold:

increasing an A3 event offset of an A3 handover event by a first offset bias; and

increasing an A4 event threshold of an A4 handover event by a first threshold bias; and

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

in response to the scheduling rate being less than a second rate threshold:

decreasing the A3 event offset of the A3 handover event by a second offset bias; and

decreasing the A4 event threshold of the A4 handover event by a second threshold bias.
The method of claim 85, wherein when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

measuring an RSRP or RSRQ of the second frequency band, wherein decreasing the A3 event offset and decreasing the A4 event threshold are further in response to the RSRP or RSRQ of the second frequency band being greater than a second reference signal threshold.
An apparatus for wireless communication, comprising:

a processing system configured to :

process an indicator from a cell of a network that the network is a high speed train network, wherein the cell is coupled to a user equipment (UE) on a first frequency band;

measure a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the UE on the first frequency band;

determine a scheduling rate of the UE on the first frequency band; and

when the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band:

in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold:

increase an A3 event offset of an A3 handover event by a first offset bias; and

increase an A4 event threshold of an A4 handover event by a first threshold bias; and

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

in response to the scheduling rate being less than a second rate threshold:

decrease the A3 event offset of the A3 handover event by a second offset bias; and

decrease the A4 event threshold of the A4 handover event by a second threshold bias.
The apparatus of claim 87, wherein when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

the processing system is further configured to measure an RSRP or RSRQ of the second frequency band, wherein decreasing the A3 event offset and decreasing the A4 event threshold are further in response to the RSRP or RSRQ of the second frequency band being greater than a second reference signal threshold.
A non-transitory, computer-readable medium storing instructions that, when executed by a processor of a user equipment (UE) , cause the UE to:

receive an indicator from a cell of a network that the network is a high speed train network, wherein the cell is coupled to the UE on a first frequency band;

measure a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the UE on the first frequency band;

determine a scheduling rate of the UE on the first frequency band; and

when the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band:

in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold:

increase an A3 event offset of an A3 handover event by a first offset bias; and

increase an A4 event threshold of an A4 handover event by a first threshold bias; and

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

in response to the scheduling rate being less than a second rate threshold:

decrease the A3 event offset of the A3 handover event by a second offset bias; and

decrease the A4 event threshold of the A4 handover event by a second threshold bias.
The computer-readable medium of claim 89, wherein execution of the instructions further cause the UE to:

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band, measure an RSRP or RSRQ of the second frequency band, wherein decreasing the A3 event offset and decreasing the A4 event threshold are further in response to the RSRP or RSRQ of the second frequency band being greater than a second reference signal threshold.
A device for wireless communication, comprising:

means for receiving an indicator from a cell of a network that the network is a high speed train network, wherein the cell is coupled to the device on a first frequency band;

means for measuring a Reference Signal Received Power (RSRP) or a Reference Signal Received Quality (RSRQ) of the device on the first frequency band;

means for determining a scheduling rate of the device on the first frequency band; and

when the first frequency band is a frequency division duplex (FDD) band of a lower frequency than a second frequency band that is a time division duplex (TDD) band:

in response to the RSRP or the RSRQ being greater than a first reference signal threshold and the scheduling rate being greater than a first rate threshold:

means for increasing an A3 event offset of an A3 handover event by a first offset bias; and

means for increasing an A4 event threshold of an A4 handover event by a first threshold bias; and

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band:

in response to the scheduling rate being less than a second rate threshold:

means for decreasing the A3 event offset of the A3 handover event by a second offset bias; and

means for decreasing the A4 event threshold of the A4 handover event by a second threshold bias.
The device of claim 91, further comprising:

when the first frequency band is a TDD band of a higher frequency than the second frequency band that is an FDD band. means for measuring an RSRP or RSRQ of the second frequency band, wherein decreasing the A3 event offset and decreasing the A4 event threshold are further in response to the RSRP or RSRQ of the second frequency band being greater than a second reference signal threshold.