WO2023064680A1

WO2023064680A1 - Dynamically disabling beam correspondence

Info

Publication number: WO2023064680A1
Application number: PCT/US2022/077179
Authority: WO
Inventors: Jibing Wang; Erik Richard Stauffer
Original assignee: Google Llc
Priority date: 2021-10-13
Filing date: 2022-09-28
Publication date: 2023-04-20

Abstract

Methods, devices, systems, and means for dynamically disabling beam correspondence by a user equipment, UE, are described herein. The UE detects a UE-local condition related to a first antenna array in use for the communication (404) and, based on the detection, transmits a disable-beam-correspondence message to the base station (406). The UE receives an uplink, UL, beam tracking pilot signal configuration from the base station (408) and, based on the received beam tracking pilot signal configuration, transmits UL beam tracking pilots that direct the base station to select an UL beam for the UE (410). The UE receives an indication of a transmit beam to use for UL communication with the base station (414) and transmits signals, to the base station, using the indicated transmit beam (416).

Description

DYNAMICALLY DISABLING BEAM CORRESPONDENCE

BACKGROUND

[0001] The evolution of wireless communication to fifth generation (5G) standards and technologies provides higher data rates and greater capacity, with improved reliability and lower latency, which enhances mobile broadband services. 5G technologies also provide new classes of service for vehicular networking, fixed wireless broadband, and the Internet of Things (loT).

[0002] At mmWave and THz radio frequencies, wireless networks use beamforming to achieve a desired signal to noise and interference ratio (SINR) to mitigate the propagation loss in these high frequency radio bands. Typically, for Time Division Duplex (TDD) bands, beam correspondence is assumed such that a user equipment (UE) can use the same beam selected for downlink (DL) reception for uplink (UL) transmission (e.g., antenna reciprocity). However, in certain scenarios such as under specific absorption rate (SAR) constraints and/or thermal conditions at the UE, the best DL beam or receiver antenna module may be different from the best UL beam or transmitter antenna module that UE can use.

SUMMARY

[0003] This summary is provided to introduce simplified concepts of dynamically disabling beam correspondence. The simplified concepts are further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining the scope of the claimed subject matter.

[0004] In aspects, methods, devices, systems, and means for determining an uplink beam by a user equipment (UE) describe a UE communicating with a base station using beamformed communications over a first beam, detecting a UE-local condition related to a first antenna array in use for the communicating, and based on the detecting, transmitting a disable-beam-correspondence indication in a message to the base station. The UE receives an uplink (UL) beam tracking pilot signal configuration from the base station, and based on the received beam tracking pilot signal configuration, transmits UL beam tracking pilots that direct the base station to select an UL beam for the UE. The UE receives an indication of a transmit beam to use for UL communication with the base station and transmits signals, to the base station, using the indicated transmit beam.

[0005] In other aspects, methods, devices, systems, and means for determining an uplink beam by a base station describe the base station communicating with a user equipment using beamformed communications over a first beam, receiving a disable-beam-correspondence indication in a message from the UE, and configuring an uplink (UL) beam tracking pilot signal configuration for the UE. The base station transmits the UL beam tracking pilot signal configuration to the UE, receives the UL beam tracking pilots from the UE, and selects an UL transmit beam for the UE. The base station transmits an indication of the UL transmit beam to use for UL communication to the UE and receives signals, from the UE, using the indicated UL transmit beam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The details of one or more aspects of dynamically disabling beam correspondence are described below. The use of the same reference numbers in different instances in the description and the figures indicate similar elements:

FIG. 1 illustrates an example operating environment in which aspects of dynamically disabling beam correspondence can be implemented.

FIG. 2 illustrates an example device diagram of a user equipment and a base station.

FIG. 3 illustrates example data and control transactions between devices in accordance with aspects of dynamically disabling beam correspondence. FIG. 4 illustrates an example method of dynamically disabling beam correspondence in accordance with aspects of the techniques described herein.

FIG. 5 illustrates an example method of dynamically disabling beam correspondence in accordance with aspects of the techniques described herein.

DETAILED DESCRIPTION

[0007] When communicating using Time Division Duplex (TDD), there is generally an assumption of reciprocity (beam correspondence) for downlink (DL) and uplink (UL) for beamformed communications. When assuming beam correspondence, a base station performs a DL beam sweep, and the UE reports the best beam to use for both DL and UL communications to the base station. The base station transmits DL data on the selected best beam, and the UE transmits UL data on the reciprocal beam.

[0008] Conditions in or around the UE (a UE-local condition) can inhibit the use of beam correspondence. For example, the use of a particular transceiver/antenna module used to form a reciprocal beam can cause overheating of that module or nearby circuitry in the UE. In another example, sensors in the UE may indicate that forming the reciprocal beam and/or transmitting using particular transceiver/antenna module used to form the reciprocal beam, may exceed specific absorption rate (SAR) and/or maximum permissible exposure (MPE) limits.

Example Environments

[0009] FIG. 1 illustrates an example environment 100, which includes a user equipment 110 (UE 110) that can communicate with base stations 120 (illustrated as base stations 121 and 122) through one or more wireless communication links 130 (wireless link 130), illustrated as wireless links 131, 132, 133, 134, and 135. The wireless communications links 133, 134, and 135 represent beamformed communications using different arrays of antenna modules in the UE 110. For example, the wireless link 134 may provide the best beam for communication with the base station 122, but if SAR constraints prohibit using the wireless link 134 for uplink transmissions, a beam provided by the wireless link 133 or 135 may provide the best available uplink beam. For simplicity, the UE 110 is implemented as a smartphone but may be implemented as any suitable computing or electronic device, such as a mobile communication device, modem, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, smart appliance, vehiclebased communication system, or an Internet-of-Things (loT) device such as a sensor or an actuator. The base stations 120 (e.g., an Evolved Universal Terrestrial Radio Access Network Node B, E- UTRANNode B, evolved Node B, eNodeB, eNB, Next Generation Node B, gNode B, gNB, ng-eNB, or the like) may be implemented in a macrocell, microcell, small cell, picocell, distributed base station, and the like, or any combination or future evolution thereof.

[0010] The base stations 120 communicate with the user equipment 110 using the wireless links 131 and 132, which may be implemented as any suitable type of wireless link. The wireless links 131 and 132 include control and data communication, such as downlink of data and control information communicated from the base stations 120 to the user equipment 110, uplink of other data and control information communicated from the user equipment 110 to the base stations 120, or both. The wireless links 130 may include one or more wireless links (e.g., radio links) or bearers implemented using any suitable communication protocol or standard, or combination of communication protocols or standards, such as 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), Fifth Generation New Radio (5GNR), and so forth. In various aspects, the base stations 120 and UE 110 may be implemented for operation in sub-gigahertz bands, sub-6 GHz bands (e.g., Frequency Range 1), and/or above-6 GHz bands (e.g., Frequency Range 2, millimeter wave (mmWave) bands) that are defined by one or more of the 3 GPP LTE, 5G NR, or 6G communication standards (e.g., 26 GHz, 28 GHz, 38 GHz, 39 GHz, 41 GHz, 57-64 GHz, 71 GHz, 81 GHz, 92 GHz bands, 100 GHz to 300 GHz, 130 GHz to 175 GHz, or 300 GHz to 3 THz bands). Multiple wireless links 130 may be aggregated in a carrier aggregation or multi -connectivity to provide a higher data rate for the UE 110. Multiple wireless links 130 from multiple base stations

120 may be configured for Coordinated Multipoint (CoMP) communication with the UE 110.

[0011] The base stations 120 are collectively a Radio Access Network 140 (e.g., RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, 5G NR RAN or NR RAN). The base stations 121 and 122 in the RAN 140 are connected to a core network 150. The base stations

121 and 122 connect, at 102 and 104 respectively, to the core network 150 through an NG2 interface for control-plane signaling and using an NG3 interface for user-plane data communications when connecting to a 5G core network, or using an SI interface for control -plane signaling and user-plane data communications when connecting to an Evolved Packet Core (EPC) network. The base stations 121 and 122 can communicate using an Xn Application Protocol (XnAP) through an Xn interface, or using an X2 Application Protocol (X2AP) through an X2 interface, at 106, to exchange user-plane and control -plane data. The user equipment 110 may connect, via the core network 150, to public networks, such as the Internet 160 to interact with a remote service 170.

Example Devices

[0012] FIG. 2 illustrates an example device diagram 200 of a user equipment and a base station. In aspects, the device diagram 200 describes devices that can implement various aspects of dynamically disabling beam correspondence. Included in FIG. 2 are the multiple UE 110 and the base stations 120. The multiple UE 110 and the base stations 120 may include additional functions and interfaces that are omitted from FIG. 2 for the sake of clarity. The UE 110 includes antennas 202, a radio frequency front end 204 (RF front end 204), and radio-frequency transceivers (e.g., an LTE transceiver 206 and a 5G NR transceiver 208) for communicating with base stations 120 in the RAN 140. The RF front end 204 of the UE 110 can couple or connect the LTE transceiver 206, and the 5G NR transceiver 208 to the antennas 202 to facilitate various types of wireless communication.

[0013] The antennas 202 of the UE 110 may include multiple antenna array modules each antenna array module including an array of multiple antennas that are configured similar to or differently from each other. The antennas 202 and the RF front end 204 can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5GNR communication standards and implemented by the LTE transceiver 206, and/or the 5G NR transceiver 208. Additionally, the antennas 202, the RF front end 204, the LTE transceiver 206, and/or the 5GNR transceiver 208 may be configured to support beamforming for the transmission and reception of communications with the base stations 120. By way of example and not limitation, the antennas 202 and the RF front end 204 can be implemented for operation in sub-gigahertz bands, sub-6 GHz bands, and/or above 6 GHz bands that are defined by the 3GPP LTE and 5G NR communication standards.

[0014] The UE 110 includes sensor(s) 210 can be implemented to detect various properties such as temperature, supplied power, power usage, battery state, proximity, touch, RF power, or the like. As such, the sensors 210 may include any one or a combination of temperature sensors, touch sensors (capacitive, resistive, infrared, surface acoustic wave, or the like) thermistors, battery sensors, proximity sensors, and RF power sensors.

[0015] The UE 110 also includes processor(s) 212 and computer-readable storage media 214 (CRM 214). The processor 212 may be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. The computer-readable storage media described herein excludes propagating signals. CRM 214 may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data 216 of the UE 110. The device data 216 includes user data, multimedia data, beamforming codebooks, applications, and/or an operating system of the UE 110, which are executable by processor(s) 212 to enable user-plane communication, control-plane signaling, and user interaction with the UE 110.

[0016] CRM 214 also includes a user equipment manager 218 (e.g., a user equipment manager application 218). Alternately or additionally, the user equipment manager 218 may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the UE 110. In at least some aspects, the user equipment manager 218 configures the RF front end 204, the LTE transceiver 206, and/or the 5GNR transceiver 208 to implement the techniques described herein for dynamically disabling beam correspondence. In aspects, the user equipment manager 218 of the UE 110 senses UE-local conditions using the sensor(s) 210 and determines to indicate to the base station 121 that the UE decides to disable beam correspondence and select a new UL transmit beam, as described with respect to FIG. 3 below.

[0017] The device diagram for the base stations 120, shown in FIG. 2, includes a single network node (e.g., a gNode B). The functionality of the base stations 120 may be distributed across multiple network nodes or devices and may be distributed in any fashion suitable to perform the functions described herein. The base stations 120 include antennas 252, a radio frequency front end 254 (RF front end 254), one or more LTE transceivers 256, and/or one or more 5GNR transceivers 258 for communicating with the UE 110. The RF front end 254 of the base stations 120 can couple or connect the LTE transceivers 256 and the 5G NR transceivers 258 to the antennas 252 to facilitate various types of wireless communication. The antennas 252 of the base stations 120 may include an array of multiple antennas that are configured similar to or differently from each other. The antennas 252 and the RF front end 254 can be tuned to, and/or be tunable to, one or more frequency band defined by the 3GPP LTE and 5GNR communication standards, and implemented by the LTE transceivers 256, and/or the 5GNR transceivers 258. Additionally, the antennas 252, the RF front end 254, the LTE transceivers 256, and/or the 5G NR transceivers 258 may be configured to support beamforming, such as Massive-MIMO, for the transmission and reception of communications with a UE 110.

[0018] The base stations 120 also include processor(s) 260 and computer-readable storage media 262 (CRM 262). The processor 260 may be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. CRM 262 may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data 264 of the base stations 120. The device data 264 includes network scheduling data, radio resource management data, beamforming codebooks, applications, and/or an operating system of the base stations 120, which are executable by processor(s) 260 to enable communication with the UE 110.

[0019] CRM 262 also includes a base station manager 266 (e.g., base station manager application 266). Alternately or additionally, the base station manager 266 may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the base stations 120. In at least some aspects, the base station manager 266 configures the LTE transceivers 256 and the 5GNR transceivers 258 for communication with the UE 110, as well as communication with a core network. The base stations 120 include an inter-base station interface 268, such as an Xn and/or X2 interface, which the base station manager 266 configures to exchange user-plane and control-plane data between another base station 120, to manage the communication of the base stations 120 with the UE 110. The base stations 120 include a core network interface 270 that the base station manager 266 configures to exchange user-plane and control -plane data with core network functions and entities. Dynamically Disabling Beam Correspondence

[0020] FIG. 3 illustrates data and control transactions between a UE and a base station in accordance with aspects of dynamically disabling beam correspondence. Although not illustrated for the sake of illustration clarity, various acknowledgements for messages illustrated in FIG. 3 may be implemented to ensure reliable operations of dynamically disabling beam correspondence.

[0021] At 305, The base station 121 and the UE 110 establish (e.g., using a Radio Resource Configuration (RRC) Connection Setup message) and conduct beamformed TDD communication. For example, the base station 121 transmits DL beam sweep pilot signals that are received by the UE 110. The UE 110 evaluates the received pilot signals and selects the beam with the best received link quality. The UE 110 sends an indication of the selected beam (e.g., an index value that identifies the beam) to the base station 121. The base station 121 and the UE 110 then use the corresponding beams for DL and UL communications. Optionally as a part of establishing beamformed communication, the UE may send its UE beam management capabilities to the base station.

[0022] At 310, the user equipment detects a UE-local condition that affects the ability of the UE to transmit using the selected, reciprocal beam. In one example, the UE calculates that using the antenna array or using certain beams of the antenna array that transmits the reciprocal UL beam would exceed a SAR or MPE constraint of the antenna array (e.g., when the UE is close to a head, hand, or body as detected by the sensor(s) 210). When the UE detects proximity or touch (using the sensor(s) 210), the UE determines how much to constrain transmit power for each available UL transmit beam to adhere to SAR/MPE limits. In another example, the UE detects that using the antenna array to transmit the reciprocal UL beam causes a transceiver module and/or other circuitry (e.g., a camera module, or a CPU) near the transceiver module to overheat. In a further example, the UE detects (e.g., using one or more touch sensors) that a user is holding the UE (as opposed to the UE being in a dashboard mount or laying on a table) and determines that the temperature of the UE is above a threshold value for holding the UE or other direct contact with skin.

[0023] At 315, based on detecting the UE-local condition, the UE 110 transmits an indication to disable beam correspondence in a message to the base station 121 that indicates that the UE 110 has decided to perform an UL beam sweep to determine a new UL beam. The UE 110 can send the disable-beam-correspondence indication using a Radio Resource Configuration (RRC) message or in a Medium Access Control (MAC) Control Element (CE). For example, the UE 110 can include the disable-beam-correspondence indication in a Tracking Area (TA) or Routing Area (RA) update message. When the UE no longer experiences the UE-local conditions, the UE can send an enablebeam-correspondence indication in a message to the base station 121 (not illustrated in FIG. 3).

[0024] At 320, based on detecting the UE-local condition, the UE 110 determines whether to modify its beam management capability. For example, if the UE sent its beam management capability to the base station at 305 and the UE-local condition dictates a change in the beam management capability, the UE sends a modified beam management capability (e.g., in the uplinkBeamManagement Information Element that defines support of beam management for UL and includes parameters such as maxNumberSRS-ResourcePerSet-BM and maxNumberSRS- ResourceSet, as defined in 3GPP TS 38.306 V15.10.0 (2020-07)) to the base station. In alternatives, the UE can send the UL beam management capability in the message including the disable-beam- correspondence indication or in a separate message. The beam management capability includes an indication of the antenna arrays that can be used for UL transmissions and the UL beams that are supported by each available antenna array. The number of UL beams supported by each antenna array may be the total number of beams the module can support or a subset of those beams, such as when some of the beams would produce RF power that violates a SAR constraint and others would not. The UE UL beam management capability changes depending on how many UE modules are usable for UL transmissions based on UE-local conditions (e.g., due to SAR and/or thermal constraints).

[0025] At 325, the base station 121 configures beam tracking pilot signals for UE UL beam sweeping in response to receiving 315 the indication to disable beam correspondence. For example, using the received UL beam management capabilities, the base station 121 configures a set of UL beam tracking pilot signals (beam identifiers and timings) based on the available transceiver modules and/or transmit beams that the UE 110 can use for transmission given the current UE-local condition(s). The base station 121 disassociates its own transmit (TX) and receive (RX) beam correspondence because, after the UL beam sweep for one or more transceiver modules, the best RX beam from the UE 110 may not be the reciprocal beam of the base station’s DL TX beam (e.g., when the UE does not use the same antenna array for transmission as reception).

[0026] At 330, the base station 121 sends an indication of the UE UL beam tracking pilot signal configuration to the UE 110. For example, the base station 121 can send the indication of the UE UL beam tracking pilot signals to the UE 110 in an RRC message (e.g., in an RRC Reconfiguration message) or MAC CE. At 335, the UE 110 configures the UL beam sweep based on the received indication of the UE UL beam tracking pilot signals, and, at 340, the UE transmits Sounding Reference Signals (SRS) or any other suitable reference signal, such as a Demodulation Reference Signal (DMRS), based on the configured UL beam sweep using the available transceiver modules and/or beams. Optionally or additionally, the base station 121 can perform a receive beam sweep to determine the best receive beam to use for each SRS transmitted by the UE 110. For example, the base station performs a receive beam sweep based on an expected range for angle of arrival of the uplink beams.

[0027] At 345, the base station evaluates each SRS (or other reference signal) received during the UL beam sweep and selects the beam with the best received signal strength for UL transmissions from the UE 110. Optionally or additionally, the base station 121 also configures its receive beam for best reception of the selected UE UL transmit beam.

[0028] At 350, the base station 121 sends a beam index as an indication of the selected beam to the UE 110. At 355, the UE transmits UL signals to the base station 121 over a Physical Uplink Shared Channel (PUSCH) or a Physical Uplink Control Channel (PUCCH) using the selected beam and one of the available transceiver modules.

[0029] At 360, the user equipment detects that the UE-local condition (overheating, SAR constraint) has been resolved. For example, the user places the UE in a dashboard mount or on a table, and the UE detects (e.g., using touch, proximity, and/or thermal sensors) that the previously detected UE-local condition no longer exists.

[0030] At 365, based on the resolution of the UE-local condition, the UE 110 transmits an indication to enable beam correspondence in a message to the base station 121 that indicates that the UE 110 has decided to resume TDD communication using beam correspondence. At 370, the UE 110 and the base station 121 resume TDD communication using beam correspondence. Resuming communication using beam correspondence may include the UE transmitting an updated beam management capability to the base station and/or the base station and UE performing a beam management procedure to establish the beam for TDD communication.

Example Methods

[0031] FIGs. 4 and 5 illustrates example method(s) 400 and 500 of dynamically disabling beam correspondence. FIG. 4 illustrates method 400 that generally relates to the user equipment dynamically disabling beam correspondence. At 402, a user equipment (e.g., the UE 110) communicates with a base station (e.g., the base station 121) using beamformed communication over a first beam. For example, the UE establishes beamformed communication with the base station using a Radio Resource Configuration (RRC) Connection Setup message and communicates over a TDD communication link using reciprocal transmit and receive beams with the base station, as described at 305 of FIG. 3.

[0032] At 404, the UE detects a UE-local condition related to a first transceiver module (e.g., the LTE transceiver 206, the 5G NR transceiver 208) or antenna array (e.g., antenna array 202) in use for the communication. For example, the UE detects a UE-local condition, such as a proximity condition or a thermal condition using one or more sensors (e.g., a touch sensor or a thermal sensor) in the UE to detect that there is a UE-local condition (e.g., thermal or SAR) that is a constraint on using the current beam for transmission, as described at 310 of FIG. 3.

[0033] At 406, based on detecting the constraint, the UE transmits a disable-beam- correspondence indicator in a message to the base station. For example, based on detecting the constraint (thermal, SAR) the UE transmits a disable-beam-correspondence indication in a message to the base station that may include UL beam capability information of the UE, as described at 315 and 320 of FIG. 3.

[0034] At 408, the UE receives an uplink beam tracking pilot signal configuration from the base station. For example, the UE receives a beam tracking pilot signal configuration in an RRC message or a MAC CE, as described at 330 of FIG. 3.

[0035] At 410, based on the received beam tracking pilot signal configuration, the UE transmits UL beam tracking pilots that direct the base station to select an UL beam for the UE. For example, the UE configures transceiver modules to transmit the SRSs specified by the received beam tracking pilot signal configuration, as described at 335 and 340 of FIG. 3.

[0036] At 412, the UE receives an indication of a transmit beam to use for UL communication with the base station. For example, the UE receives an indication of a transmit beam to use for UL communication from the base station in an RRC message or a MAC CE, as described at 350 of FIG. 3.

[0037] At 414, the UE transmits signals, to the base station, using the indicated transmit beam. For example, to mitigate the UE-local condition, the UE transmits control and data using the indicated transmit beam, as described at 355 of FIG. 3.

[0038] At 416, the UE detects the resolution of, or a change to, the UE-local condition. For example, the UE detects a change in the UE-local condition, such as a user changing from holding the UE in the user’s hand to holding the UE to the user’s ear. Based on detecting this change, the method continues at 418, where the UE transmits a modified beam management capability to the base station and then the method continues at 408. If the UE determines that the UE-local condition is resolved, the UE transmits an enable-beam-correspondence indicator in a message to the base station. For example, the UE detects, using proximity and/or touch sensors that the user has placed the UE back on the surface of a table, thus resolving the constraint (thermal, S AR), the UE transmits a enablebeam-correspondence indication in a message to the base station, as described at 365 of FIG. 3 and the method continues at 402. If the UE determines that the UE-local condition is unchanged, the method continues at 414.

[0039] FIG. 5 illustrates method 500 that generally relates to the base station dynamically disabling beam correspondence. At 502, a base station (e.g., the base station 121) communicates with a user equipment (e.g., the UE 110) using beamformed communications over a first beam. For example, the base station stablishes beamformed communication with the UE using a Radio Resource Configuration (RRC) Connection Setup message and communicates with the UE over a TDD communication link using reciprocal transmit and receive beams with the UE, as described at 305 of

FIG. 3. [0040] At 504, the base station receives a disable-beam-correspondence indicator in a message from the UE. For example, the base station receives a disable-beam-correspondence indication in a message from the UE that may include UL beam management capability information of the UE, as described at 315 and 320 of FIG. 3.

[0041] At 506, the base station configures an uplink beam tracking pilot signal configuration for the UE. For example, using the UL beam management capability information of the UE, the base station configures an uplink beam tracking pilot signal configuration for the UE as described at 325 of FIG. 3.

[0042] At 508, the base station transmits the UL beam tracking pilot signal configuration to the UE. For example, the base station transmits the UL beam tracking pilot signal configuration to the UE in an RRC message or a MAC CE, as described at 330 in FIG. 3.

[0043] At 510, the base station receives the UL beam tracking pilots from the UE. For example, based on the UL beam tracking pilot signal configuration, the UE transmits UL beam tracking pilots to the base station. The base station may perform a receive beam sweep for each of the UL tracking pilots to determine the best receive beam for each candidate UL beam, as described at 340 in FIG. 3.

[0044] At 512, the base station selects an UL transmit beam for the UE. For example, the base station evaluates the signal strength and/or quality for each of the UL beam tracking pilots and selects the best beam for the UL beam from the UE, as described at 345 in FIG. 3

[0045] At 514, the base station transmits an indication of the UL transmit beam to use for UL communication to the UE. For example, the base station transmits an indication of the UL transmit beam to use for UL communication to the UE in an RRC message or a MAC CE, as described at 350 in FIG. 3 [0046] At 516, the base station receives signals, from the UE, using the indicated UL transmit beam. For example, the base station receives control and data, from the UE, using the selected UL transmit beam that is not a corresponding (reciprocal) beam of the DL transmit beam of the base station, as described at 355 in FIG. 3

[0047] Example methods 400 and 500 are described with reference to FIGs. 4 and 5 in accordance with one or more aspects of dynamically disabling beam correspondence. The order in which the method blocks are described are not intended to be construed as a limitation, and any number of the described method blocks can be skipped, repeated, or combined in any order to implement a method or an alternate method. Generally, any of the components, modules, methods, and operations described herein can be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the example methods may be described in the general context of executable instructions stored on computer- readable storage memory that is local and/or remote to a computer processing system, and implementations can include software applications, programs, functions, and the like. Alternatively or in addition, any of the functionality described herein can be performed, at least in part, by one or more hardware logic components, such as, and without limitation, Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SoCs), Complex Programmable Logic Devices (CPLDs), and the like.

[0048] In the following some examples are described:

Example 1 : A method for determining an uplink beam by a user equipment, UE, the method comprising: communicating, with a base station, using beamformed communications over a first beam; detecting a UE-local condition related to a first antenna array in use for the communicating; based on the detecting, transmitting a disable-beam-correspondence indication in a message to the base station; receiving an uplink, UL, beam tracking pilot signal configuration from the base station; based on the received UL beam tracking pilot signal configuration, transmitting UL beam tracking pilots; receiving an indication of a transmit beam to use for UL communication with the base station; and transmitting signals, to the base station, using the indicated transmit beam.

Example 2: The method of example 1, further comprising: transmitting UL beam management capability information to the base station.

Example 3 : The method of example 2, wherein the transmitting the UL beam management capability information to the base station comprises: transmitting an indication of antenna arrays usable for UL transmissions.

Example 4: The method of example 2 or example 3, wherein the transmitting the UL beam management capability information to the base station comprises: transmitting an indication of UL beams usable for UL transmissions.

Example 5: The method of any one of examples 2 to 4, wherein the transmitting a disable-beam- correspondence indication comprises: including the disable-beam-correspondence indication and the UL beam management capability information in a message. Example 6: The method of any one of examples 2 to 4, wherein the transmitting the UL beam capability information to the base station comprises: transmitting the UL beam capability information in a message that does not include the disable-beam-correspondence indication.

Example 7: The method of any one of examples 1 to 3, wherein the receiving the indication of the transmit beam to use for UL communication comprises: receiving an indication to transmit the beam using a second antenna array.

Example 8: The method of any one of the preceding examples, wherein the detecting the UE-local condition comprises: detecting one or more of: a thermal condition; exceeding a calculated Specific Absorption Rate, SAR, constraint; or exceeding a calculated Maximum Permissible Exposure, MPE, constraint.

Example 9: The method of any one of the preceding examples, wherein the communicating using the beamformed communications comprises: communicating using Time Division Duplex, TDD.

Example 10: The method of any one of the preceding examples, wherein the transmitting the disable-beam-correspondence indication to the base station comprises: transmitting the disable-beam-correspondence indication to the base station in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

Example 11 : The method of any one of the preceding examples, wherein the receiving the indication of the transmit beam to use for UL communication with the base station comprises: receiving the indication of the transmit beam to use for UL communication with the base station in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

Example 12: The method of any one of the preceding examples, wherein the communicating, with the base station, using the beamformed communications over a first beam comprises: transmitting signals to the base station; receiving signals from the base station; or both transmitting signal to and receiving signals from the base station.

Example 13: The method of any one of the preceding examples, the method further comprising: detecting that the UE-local condition is resolved; and based on the detecting that the UE-local condition is resolved, transmitting an enable-beam- correspondence indication in a message to the base station.

Example 14: A method for determining an uplink beam by a base station, the method comprising: communicating, with a user equipment, UE, using beamformed communications over a first beam; receiving a disable-beam-correspondence indication in a message from the UE; configuring an uplink, UL, beam tracking pilot signal configuration for the UE; transmitting the UL beam tracking pilot signal configuration to the UE; receiving the UL beam tracking pilots from the UE; selecting an UL transmit beam for the UE; transmitting an indication of the UL transmit beam to use for UL communication to the UE; and receiving signaling, from the UE, using the indicated UL transmit beam.

Example 15: The method of example 14, further comprising: receiving UL beam management capability information from the UE.

Example 16: The method of example 15, wherein the receiving the UL beam management capability information from the UE comprises: receiving an indication of antenna arrays usable for UL transmissions.

Example 17: The method of any one of examples 14 to 1616, wherein the configuring the UL beam tracking pilot signal configuration for the UE comprises: configuring the UL beam tracking pilot signal configuration to use one or more UE antenna arrays other than the antenna array transmitting the first beam.

Example 18: The method of examples 15, wherein the receiving the UL beam management capability information from the UE comprises: receiving an indication of UL antenna arrays or beams usable for UL transmissions. Example 19: The method of any one of examples 14 to 18, wherein the receiving the UL beam tracking pilots from the UE further comprises: performing, by the base station, a receiver beam sweep to determine the best receive beam for each of the UL beam tracking pilots transmitted by the UE.

Example 20: The method of any one of examples 14 to 19, wherein the selected UL beam is other than a reciprocal beam of the first beam.

Example 21 : The method of any one of examples 14 to 20, wherein the receiving the disable-beam- correspondence indication from the UE comprises: receiving the disable-beam-correspondence indication in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

Example 22: The method of any one of examples 14 to 21, wherein the transmitting the indication of the UL transmit beam to use for UL communication comprises: transmitting the indication of the UL transmit beam to use for UL communication in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

Example 23: The method of example 22, wherein the RRC message is an RRC Connection Reconfiguration message.

Example 24: The method of any one of examples 14 to 21, wherein the communicating, with the

UE, using the beamformed communications over a first beam comprises: transmitting signals to the UE; receiving signals from the UE; or both transmitting signals to and receiving signals from the UE.

Example 25: An apparatus comprising: a wireless transceiver; a processor; and computer-readable storage media comprising instructions that, responsive to execution by the processor, direct the apparatus to perform a method as recited in any one of examples 1 to 24.

Example 26: Computer-readable storage media comprising instructions that, responsive to execution by a processor, direct an apparatus to perform a method as recited in any one of examples 1 to 24.

[0049] Although aspects of dynamically disabling beam correspondence have been described in language specific to features and/or methods, the subject of the appended claims is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as example implementations of dynamically disabling beam correspondence, and other equivalent features and methods are intended to be within the scope of the appended claims. Further, various different aspects are described, and it is to be appreciated that each described aspect can be implemented independently or in connection with one or more other described aspects.

Claims

1. A method for determining an uplink beam by a user equipment, UE, the method comprising: communicating, with a base station, using beamformed communications over a first beam; detecting a UE-local condition related to a first antenna array in use for the communicating; based on the detecting, transmitting a disable-beam-correspondence indication to the base station; receiving an uplink, UL, beam tracking pilot signal configuration from the base station; based on the received UL beam tracking pilot signal configuration, transmitting UL beam tracking pilots; receiving an indication of a transmit beam to use for UL communication with the base station; and transmitting signals, to the base station, using the indicated transmit beam.

2. The method of claim 1, further comprising: transmitting UL beam management capability information to the base station.

3. The method of claim 2, wherein the transmitting the UL beam management capability information to the base station comprises: transmitting an indication of antenna arrays usable for UL transmissions.

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4. The method of claim 2 or claim 3, wherein the transmitting the UL beam management capability information to the base station comprises: transmitting an indication of UL beams usable for UL transmissions.

5. The method of any one of claims 2 to 4, wherein the transmitting a disable-beam- correspondence indication comprises: including the disable-beam-correspondence indication and the UL beam management capability information in a message.

6. The method of any one of claims 2 to 4, wherein the transmitting the UL beam capability information to the base station comprises: transmitting the UL beam capability information in a message that does not include the disable-beam-correspondence indication.

7. The method of any one of the preceding claims, wherein the detecting the UE-local condition comprises: detecting one or more of: a thermal condition; exceeding a calculated Specific Absorption Rate, SAR, constraint; or exceeding a calculated Maximum Permissible Exposure, MPE, constraint.

8. The method of any one of the preceding claims, wherein the communicating using the beamformed communications comprises: communicating using Time Division Duplex, TDD.

9. The method of any one of the preceding claims, wherein the transmitting the disablebeam-correspondence indication to the base station comprises: transmitting the disable-beam-correspondence indication to the base station in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE; and wherein the receiving the indication of the transmit beam to use for UL communication with the base station comprises: receiving the indication of the transmit beam to use for UL communication with the base station in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

10. The method of any one of the preceding claims, the method further comprising: detecting that the UE-local condition is resolved; and based on the detecting that the UE-local condition is resolved, transmitting an enable-beam- correspondence indication in a message to the base station.

11. A method for determining an uplink beam by a base station, the method comprising: communicating, with a user equipment, UE, using beamformed communications over a first beam; receiving a disable-beam-correspondence indication from the UE; configuring an uplink, UL, beam tracking pilot signal configuration for the UE; transmitting the UL beam tracking pilot signal configuration to the UE; receiving the UL beam tracking pilots from the UE; selecting an UL transmit beam for the UE; transmitting an indication of the UL transmit beam to use for UL communication to the UE; and receiving signaling, from the UE, using the indicated UL transmit beam.

12. The method of claim 11, further comprising: receiving UL beam management capability information from the UE.

13. The method of claim 12, wherein the receiving the UL beam management capability information from the UE comprises: receiving an indication of antenna arrays usable for UL transmissions.

14. The method of any one of claims 11 to 13, wherein the configuring the UL beam tracking pilot signal configuration for the UE comprises: configuring the UL beam tracking pilot signal configuration to use one or more UE antenna arrays other than the antenna array transmitting the first beam.

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15. The method of claim 12, wherein the receiving the UL beam management capability information from the UE comprises: receiving an indication of UL antenna arrays or beams usable for UL transmissions.

16. The method of any one of claims 11 to 15, wherein the receiving the UL beam tracking pilots from the UE further comprises: performing, by the base station, a receiver beam sweep to determine the best receive beam for each of the UL beam tracking pilots transmitted by the UE.

17. The method of any one of claims 11 to 16, wherein the selected UL beam is other than a reciprocal beam of the first beam.

18. The method of any one of claims 11 to 17, wherein the receiving the disable-beam- correspondence indication from the UE comprises: receiving the disable-beam-correspondence indication in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE; and wherein the transmitting the indication of the UL transmit beam to use for UL communication comprises: transmitting the indication of the UL transmit beam to use for UL communication in: a Radio Resource Control, RRC, message; or a Medium Access Control, MAC, Control Element, CE.

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19. The method of claim 18, wherein the RRC message is an RRC Connection Reconfiguration message.

20. An apparatus comprising: a wireless transceiver; a processor; and computer-readable storage media comprising instructions that, responsive to execution by the processor, direct the apparatus to perform a method as recited in any one of claims 1 to 19.

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