WO2020220372A1 - Rétablissement après défaillance de faisceau au moyen d'une procédure de canal d'accès aléatoire sans contention en deux étapes - Google Patents

Rétablissement après défaillance de faisceau au moyen d'une procédure de canal d'accès aléatoire sans contention en deux étapes Download PDF

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Publication number
WO2020220372A1
WO2020220372A1 PCT/CN2019/085403 CN2019085403W WO2020220372A1 WO 2020220372 A1 WO2020220372 A1 WO 2020220372A1 CN 2019085403 W CN2019085403 W CN 2019085403W WO 2020220372 A1 WO2020220372 A1 WO 2020220372A1
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WO
WIPO (PCT)
Prior art keywords
bfr
communication
resources
target beam
identifies
Prior art date
Application number
PCT/CN2019/085403
Other languages
English (en)
Inventor
Linhai He
Ruiming Zheng
Jing LEI
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Qualcomm Incorporated
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Publication date
Application filed by Qualcomm Incorporated filed Critical Qualcomm Incorporated
Priority to PCT/CN2019/085403 priority Critical patent/WO2020220372A1/fr
Publication of WO2020220372A1 publication Critical patent/WO2020220372A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access, e.g. scheduled or random access
    • H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
    • H04W74/0833—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
    • H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0091—Signaling for the administration of the divided path
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA

Definitions

  • a wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) .
  • a user equipment (UE) may communicate with a base station (BS) via the downlink and uplink.
  • the downlink (or forward link) refers to the communication link from the BS to the UE
  • the uplink (or reverse link) refers to the communication link from the UE to the BS.
  • a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , a New Radio (NR) BS, a 5G Node B, and/or the like.
  • NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.
  • OFDM orthogonal frequency division multiplexing
  • SC-FDM e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)
  • DFT-s-OFDM discrete Fourier transform spread OFDM
  • MIMO multiple-input multiple-output
  • a method of wireless communication may include transmitting a communication, associated with performing a beam failure recovery (BFR) procedure, using one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a physical uplink shared channel (PUSCH) .
  • BFR beam failure recovery
  • a UE for wireless communication may include memory and one or more processors operatively coupled to the memory.
  • the memory and the one or more processors may be configured to transmit a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a PUSCH.
  • a non-transitory computer-readable medium may store one or more instructions for wireless communication.
  • the one or more instructions when executed by one or more processors of a UE, may cause the one or more processors to: transmit a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a PUSCH.
  • an apparatus for wireless communication may include means for transmitting a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the apparatus, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a PUSCH.
  • a method of wireless communication may include detecting a beam failure associated with an active bandwidth part (BWP) of the UE; measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; determining that a set of beam failure recovery (BFR) resources is configured for the active BWP; and transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a physical uplink shared channel (PUSCH)
  • BWP active bandwidth part
  • a method of wireless communication may include detecting a beam failure associated with a serving cell of the UE, wherein the UE is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell, the serving cell being one of the primary cell or the secondary cell; measuring, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell; selecting a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell; and transmitting a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of the UE, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the
  • PRACH physical random access channel
  • a method of wireless communication may include detecting a beam failure associated with an active BWP of the UE; measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; switching to an initial BWP, associated with the UE, based at least in part on determining that no BFR resources are configured for the active BWP; and transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of a set of BFR resources configured for the initial BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a physical random access channel (PRACH) ,
  • a UE for wireless communication may include memory and one or more processors operatively coupled to the memory.
  • the memory and the one or more processors may be configured to detect a beam failure associated with an active BWP of the UE; measure, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; select a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; determine that a set of BFR resources is configured for the active BWP; and transmit a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a
  • a non-transitory computer-readable medium may store one or more instructions for wireless communication.
  • the one or more instructions when executed by one or more processors of a UE, may cause the one or more processors to: detect a beam failure associated with an active BWP of the UE; measure, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; select a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; determine that a set of BFR resources is configured for the active BWP; and transmit a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR,
  • an apparatus for wireless communication may include means for detecting a beam failure associated with an active BWP of the apparatus; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; means for selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; means for determining that a set of BFR resources is configured for the active BWP; and means for transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a physical uplink shared channel (PUSCH) .
  • PRACH physical random access channel
  • a non-transitory computer-readable medium may store one or more instructions for wireless communication.
  • the one or more instructions when executed by one or more processors of a UE, may cause the one or more processors to: detect a beam failure associated with an active BWP of the UE; measure, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; select a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; switch to an initial BWP, associated with the UE, based at least in part on determining that no BFR resources are configured for the active BWP; and transmit a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of a set of BFR resources configured for the initial BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and where
  • an apparatus for wireless communication may include means for detecting a beam failure associated with an active BWP of the apparatus; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; means for selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; means for switching to an initial BWP, associated with the apparatus, based at least in part on determining that no BFR resources are configured for the active BWP; and means for transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of a set of BFR resources configured for the initial BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a
  • a UE for wireless communication may include memory and one or more processors operatively coupled to the memory.
  • the memory and the one or more processors may be configured to detect a beam failure associated with a serving cell of the UE, wherein the UE is configured to communicate based at least in a CA configuration associated with a primary cell and a secondary cell, the serving cell being one of the primary cell or the secondary cell; measure, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell; select a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell; and transmit a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of the UE, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information
  • a non-transitory computer-readable medium may store one or more instructions for wireless communication.
  • the one or more instructions when executed by one or more processors of a UE, may cause the one or more processors to: detect a beam failure associated with a serving cell of the UE, wherein the UE is configured to communicate based at least in part a CA configuration associated with a primary cell and a secondary cell, the serving cell being one of the primary cell or the secondary cell; measure, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell; select a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell; and transmit a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of the UE, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random
  • an apparatus for wireless communication may include means for detecting a beam failure associated with a serving cell of the apparatus, wherein the apparatus is configured to communicate based at least in part on a CA configuration associated with a primary cell and a secondary cell, the serving cell being one of the primary cell or the secondary cell; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell; means for selecting a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell; and means for transmitting a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of the apparatus, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies
  • a method of wireless communication may include receiving a communication, associated with a beam failure recovery (BFR) procedure, in one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with a user equipment (UE) , the preamble sequence being received over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a physical uplink shared channel (PUSCH) .
  • BFR beam failure recovery
  • a base station for wireless communication may include memory and one or more processors operatively coupled to the memory.
  • the memory and the one or more processors may be configured to receive a communication, associated with a beam failure recovery (BFR) procedure, in one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with a user equipment (UE) , the preamble sequence being received over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a physical uplink shared channel (PUSCH) .
  • BFR beam failure recovery
  • a non-transitory computer-readable medium may store one or more instructions for wireless communication.
  • the one or more instructions when executed by one or more processors of a base station, may cause the one or more processors to: receive a communication, associated with a beam failure recovery (BFR) procedure, in one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with a user equipment (UE) , the preamble sequence being received over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a physical uplink shared channel (PUSCH) .
  • BFR beam failure recovery
  • an apparatus for wireless communication may include means for receiving a communication, associated with a beam failure recovery (BFR) procedure, in one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with a user equipment (UE) , the preamble sequence being received over a physical random access channel (PRACH) , and wherein the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a physical uplink shared channel (PUSCH) .
  • BFR beam failure recovery
  • aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and processing system as substantially described herein with reference to and as illustrated by the accompanying drawings, appendix, and specification.
  • Fig. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure.
  • Figs. 3-5 are diagrams illustrating examples of beam failure recovery using a two-step contention free random access procedure, in accordance with various aspects of the present disclosure.
  • Figs. 6-10 are diagrams illustrating example processes performed, for example, by wireless communication devices, in accordance with various aspects of the present disclosure.
  • Fig. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced.
  • the wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network.
  • the wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities.
  • a BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/or the like.
  • Each BS may provide communication coverage for a particular geographic area.
  • the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.
  • a BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell.
  • a macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription.
  • a pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription.
  • a femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) .
  • a BS for a macro cell may be referred to as a macro BS.
  • eNB base station
  • NR BS NR BS
  • gNB gNode B
  • AP AP
  • node B node B
  • 5G NB 5G NB
  • cell may be used interchangeably herein.
  • Wireless network 100 may also include relay stations.
  • a relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) .
  • a relay station may also be a UE that can relay transmissions for other UEs.
  • a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d.
  • a relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.
  • Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100.
  • macro BSs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 Watts) .
  • a network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs.
  • Network controller 130 may communicate with the BSs via a backhaul.
  • the BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.
  • UEs 120 may be dispersed throughout wireless network 100, and each UE may be stationary or mobile.
  • a UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like.
  • a UE may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.
  • PDA personal digital assistant
  • WLL wireless local loop
  • MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and/or the like, that may communicate with a base station, another device (e.g., remote device) , or some other entity.
  • a wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link.
  • Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as NB-IoT (narrowband internet of things) devices.
  • Some UEs may be considered a Customer Premises Equipment (CPE) .
  • UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like.
  • any number of wireless networks may be deployed in a given geographic area.
  • Each wireless network may support a particular RAT and may operate on one or more frequencies.
  • a RAT may also be referred to as a radio technology, an air interface, and/or the like.
  • a frequency may also be referred to as a carrier, a frequency channel, and/or the like.
  • Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.
  • NR or 5G RAT networks may be deployed.
  • Fig. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 1.
  • Base station 110 may be equipped with T antennas 234a through 234t
  • UE 120 may be equipped with R antennas 252a through 252r, where in general T ⁇ 1 and R ⁇ 1.
  • a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS (s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols.
  • MCS modulation and coding schemes
  • Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) .
  • a transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream.
  • TX transmit
  • MIMO multiple-input multiple-output
  • Each modulator 232 may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream.
  • Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal.
  • T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.
  • the synchronization signals can be generated with location encoding to convey additional information.
  • antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively.
  • Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples.
  • Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols.
  • a MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.
  • a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110.
  • modulators 254a through 254r e.g., for DFT-s-OFDM, CP-OFDM, and/or the like
  • the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120.
  • Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240.
  • Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244.
  • Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.
  • Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with beam failure recovery (BFR) using a two-step contention free random access channel (CFRA) procedure, as described in more detail elsewhere herein.
  • controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 600 of Fig. 6, process 700 of Fig. 7, process 800 of Fig. 8, process 900 of Fig. 9, process 1000 of Fig. 10, and/or other processes as described herein.
  • Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively.
  • a scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.
  • UE 120 may include means for detecting a beam failure associated with an active bandwidth part (BWP) of the apparatus; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; means for selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; means for determining that a set of BFR resources is configured for the active BWP; means for transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP, wherein the communication is associated with a two-step CFRA procedure, and wherein the communication includes information that identifies the target beam associated with the active BWP; and/or the like.
  • such means may include one or more components of UE 120 described in connection with Fig. 2.
  • UE 120 may include means for transmitting a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the apparatus, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a PUSCH; and/or the like.
  • such means may include one or more components of UE 120 described in connection with Fig. 2.
  • UE 120 may include means for detecting a beam failure associated with an active BWP of UE 120; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP; means for selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams; means for switching to an initial BWP, associated with UE 120, based at least in part on determining that no BFR resources are configured for the active BWP; means for transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of a set of BFR resources configured for the initial BWP, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target beam being transmitted over a PUSCH; and/or the
  • UE 120 may include means for detecting a beam failure associated with a serving cell of UE 120, wherein UE 120 is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell, the serving cell being one of the primary cell or the secondary cell; means for measuring, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell; means for selecting a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell; means for transmitting a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of UE 120, wherein the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a PRACH, and wherein the communication includes information that identifies a target beam associated with performing the BFR, the information that identifies the target
  • CA
  • a base station 110 may include means for receiving a communication, associated with a BFR procedure, in one or more BFR resources of a set of BFR resources, wherein the communication is associated with transmission of a preamble sequence uniquely associated with UE 120, the preamble sequence being received over a PRACH, and wherein the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a PUSCH.
  • Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.
  • a two-step random access channel (RACH) procedure includes two steps (rather than four steps, as in a traditional four-step contention based RACH (CBRA) procedure) .
  • a UE transmits a first communication (sometimes referred to as msgA) that includes a randomly selected preamble and a payload (e.g., a physical uplink shared channel (PUSCH) payload) .
  • a base station after receiving the communication and processing the RACH request associated with the first communication, transmits a second communication (aresponsive communication, sometimes referred to as msgB) to the UE to confirm completion of the RACH request.
  • msgA first communication
  • PUSCH physical uplink shared channel
  • a contention free RACH (CFRA) procedure also includes two steps (e.g., because the network provides a dedicated preamble for a given UE and, therefore, there is no contention involved) .
  • CFRA procedure there are two kinds of events that can use the CFRA procedure: handover and beam failure recovery (BFR) .
  • BFR resources dedicated resources to be used in association with performing BFRs.
  • Each RACH occasion in this dedicated configuration corresponds to a respective one of a set of candidate beams configured for a UE.
  • the set of candidate beams for the UE can be defined on a per bandwidth part (BWP) basis.
  • BWP bandwidth part
  • Each UE is also configured with a dedicated preamble that represents the UE (which differs from a contention based scenario in which the UE randomly selects a preamble from a predefined set of preambles) .
  • a UE first determines in which BWP to perform a BFR. If a set of BFR resources is configured for the current active BWP, then the UE remains in the active BWP and performs a BFR. Otherwise, the UE switches to an initial BWP and performs the BFR in the initial BWP.
  • the UE selects a target beam as a new serving beam from the set of candidate beams configured for the BWP in which the UE is to perform the BFR (i.e., the active BWP or the initial BWP) .
  • the UE transmits its dedicated preamble in a RACH occasion that corresponds to the target beam.
  • the UE monitors a BFR search space on a physical downlink control channel (PDCCH) for a communication addressed to a cell radio network temporary identifier (C-RNTI) assigned to the UE.
  • PDCCH physical downlink control channel
  • C-RNTI cell radio network temporary identifier
  • the RACH portion of the BFR is complete if the UE receives such a PDCCH communication.
  • the network e.g., a base station in the network
  • TCI transmission configuration indicator
  • Some aspects described herein provide techniques and apparatuses for BFR using a two-step CFRA procedure.
  • a UE when performing the BFR using the two-step CFRA procedure, can include additional information in a payload of a first communication associated with performing the BFR, which reduces overall latency of the BFR procedure, as described below. Additional details regarding performing a BFR using a two-step CFRA procedure are described below.
  • Figs. 3-5 are diagrams illustrating examples associated with BFR using a two-step CFRA procedure, in accordance with various aspects of the present disclosure.
  • a UE may transmit a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources.
  • the communication may be associated with transmission of a preamble sequence uniquely associated with the UE (i.e., a dedicated preamble) , and the preamble sequence may be transmitted over, for example, a physical random access channel (PRACH) .
  • PRACH physical random access channel
  • the communication may include information that identifies a target beam associated with performing the BFR procedure, and the information that identifies the target beam may be transmitted over, for example, a physical uplink shared channel (PUSCH) .
  • PUSCH physical uplink shared channel
  • Fig. 3 is a diagram illustrating an example 300 associated with BFR using a two-step CFRA procedure when a set of BFR resources is configured for an active BWP associated with a UE.
  • a UE may detect a beam failure associated with an active BWP of the UE, and may measure, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP (e.g., a set of possible target beams for the UE to recover a link with a base station) .
  • An active BWP is a BWP used for communication of uplink and downlink traffic (as compared to an initial BWP, which is a BWP used for initial connection setup and initial configuration) .
  • an active BWP has a wider bandwidth than an initial BWP and, therefore, can be used to achieve comparatively higher throughput.
  • a UE uses an initial BWP during initial connection setup and initial configuration, and then switches to an active BWP for use in association with transmitting and receiving traffic after the initial connection and configuration is complete.
  • the UE may select a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams.
  • the target beam is a candidate beam with a characteristic (e.g., a reference signal received power (RSRP) ) that satisfies a threshold for link recovery.
  • RSRP reference signal received power
  • the UE may determine whether a set of BFR resources is configured for the active BWP. In some aspects, the UE may determine whether a set of BFR resources is configured for the active BWP based at least in part on configuration information accessible by the UE (e.g., when the UE has previously received a configuration indicating BFR resources are configured for the active BWP) . As shown by reference 306, in some aspects, the UE may determine that a set of BFR resources is configured for the active BWP. An example in which the UE determines that no BFR resources are configured for the active BWP is described below in association with Fig. 4.
  • the UE may transmit a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP.
  • the communication includes the dedicated preamble associated with the UE, as well as information that identifies the target beam associated with the active BWP.
  • the information that identifies the target beam may include, for example, an index corresponding to the target beam (e.g., such that the target beam can be identified using the index) .
  • the information that identifies the target beam may be transmitted in a payload of the communication (e.g., in a msgA payload) .
  • the information that identifies the target beam is transmitted in a medium access control (MAC) control element (CE) .
  • the communication may include a dedicate preamble associated with the UE, and the dedicated preamble may be transmitted over a PRACH.
  • the communication may include the information that identifies the target beam, and the information that identifies the target beam may be transmitted over a PUSCH.
  • the UE can transmit the communication using one or more BFR resources, of the set of BFR resources, that do not correspond to the target beam.
  • the UE can select any usable beam in association with performing the BFR.
  • the UE can transmit the communication without waiting for a RACH occasion including BFR resources that correspond to the target beam, thereby reducing RACH latency and overall latency associated with performing the BFR.
  • the one or more BFR resources in which the communication is transmitted may precede (e.g., in the time domain) one or more other BFR resources, of the set of BFR resources, that correspond to the target beam.
  • the UE may be configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell (e.g., a cell associated with sub-6 GHz communications) and a secondary cell (e.g., a cell associated with millimeter wave communications) .
  • CA carrier aggregation
  • BFR resources can be configured for both the primary cell and the secondary cell.
  • the above-described two-step CFRA BFR technique can be used when the active BWP is associated with the primary cell or when the active BWP is associated with the secondary cell. In other words, either one of the primary and secondary cells can perform BFR separately (in whichever cell the beam failure occurs) .
  • the BFR using the two-step CFRA procedure as described in association with Fig. 3 does not require dedicated resources for transmitting the payload including the information that identifies the target beam and, therefore, is not costly in terms of resource usage.
  • performances of BFR occur relatively rarely for a given UE, and it is even more rare that multiple UEs experience beam failures at the same time.
  • This allows multiple UEs to share uplink resources (e.g., PUSCH resources) for transmitting a communication associated with the two-step CFRA BFR.
  • uplink resources e.g., PUSCH resources
  • each UE still has a respective dedicated preamble and can identify RACH occasions (e.g., as in regular CFRA BFR) .
  • multiple preambles can be mapped to the same uplink resource (e.g., the same one or more BFR resources) .
  • the network can still decode each UE’s dedicated preamble, but cannot decode the payloads.
  • the network can provide a respective uplink grant to each UE, and each UE can transmit another communication, including the payload, using a set of resources identified by the uplink grant. Accordingly, there is no need for dedicated uplink recourses for transmitting the first communication (i.e., the uplink resources can be shared) .
  • Fig. 3 is provided as an example. Other examples may differ from what is described with respect to Fig. 3.
  • Fig. 4 is a diagram illustrating an example 400 associated with BFR using a two-step CFRA procedure when no BFR resources are configured for an active BWP associated with a UE.
  • a UE may detect a beam failure associated with an active BWP of the UE, and may measure, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP (e.g., in a manner similar to that described above in association with Fig. 3) .
  • the UE may select a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams (e.g., in a manner similar to that described above in association with Fig. 3) .
  • the UE may determine whether a set of BFR resources is configured for the active BWP. As shown by reference 406, in some aspects, the UE may determine that no BFR resources are configured for the active BWP. For example, the UE may receive a configuration indicating a set of BFR resources configured for an initial BWP only (i.e., a configuration that does not indicate BFR resources for the active BWP) , and may determine that no BFR resources are configured for the active BWP.
  • the UE may switch to an initial BWP associated with the UE (from the active BWP) .
  • the UE may transmit a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the initial BWP.
  • the communication includes the dedicated preamble associated with the UE, as well as information that identifies the target beam associated with the active BWP (e.g., an index corresponding to the target beam) .
  • the information that identifies the target beam may be transmitted in a payload of the communication (e.g., in a msgA payload) .
  • the information that identifies the target beam is transmitted in a MAC-CE.
  • the communication may include a dedicate preamble associated with the UE, and the dedicated preamble may be transmitted over a PRACH.
  • the communication may include the information that identifies the target beam, and the information that identifies the target beam may be transmitted over a PUSCH.
  • the communication may include information that identifies the active BWP.
  • the payload of the communication may include an index or identifier that identifies the active BWP.
  • the information that identifies the target beam may further identify the active BWP.
  • the information that identifies the target beam may also identify the active BWP (e.g., when unique indices are assigned to target beams across different BWPs) .
  • the UE transmits the communication using one or more BFR resources that do not correspond to the target beam.
  • the one or more BFR resources in which the UE transmits the communication need not correspond to the target beam associated with the active BWP.
  • the UE can select any usable beam, associated with the initial BWP, and use the selected beam for transmitting the communication in association with performing the BFR, thereby reducing RACH latency and overall latency associated with performing the BFR.
  • the one or more BFR resources in which the communication is transmitted need not correspond or be related to the target beam (e.g., since the communication includes the information that identifies the target beam) .
  • the network e.g., a base station 110
  • the network can indicate to the UE to switch back to the active BWP, and the UE can switch back the active BWP, accordingly.
  • the network can directly configure a TCI state of the UE based at least in part on the target beam indicated by the UE in the first communication. Notably, there is no need to perform beam management associated with the UE in this case, thereby reducing latency of beam recovery.
  • the UE may be configured to communicate based at least in a CA configuration associated with a primary cell and a secondary cell.
  • BFR resources can be configured for both the primary cell and the secondary cell.
  • the above-described two-step CFRA BFR technique can be used when the active BWP and the initial BWP are associated with the primary cell or when the active BWP and the initial BWP are associated with the secondary cell. In other words, either one of the primary and secondary cells can perform BFR separately (in whichever cell the beam failure occurs) .
  • the BFR using the two-step CFRA procedure as described in association with Fig. 4 does not require dedicated resources for transmitting the payload including the information that identifies the target beam and, therefore, is not costly in terms of resource usage (e.g., for similar reasons as described in association with Fig. 3) .
  • the network can provide a respective uplink grant to each UE, and each UE can transmit another communication, including the payload, using a set of resources identified by the uplink grant. Accordingly, there is no need for dedicated uplink recourses for transmitting the first communication (i.e., the uplink resources can be shared) .
  • Fig. 4 is provided as an example. Other examples may differ from what is described with respect to Fig. 4.
  • the UE may be configured to communicate based at least in a CA configuration associated with a primary cell (e.g., a cell associated with sub-6 GHz communications) and a secondary cell (e.g., a cell associated with millimeter wave communications) .
  • BFR resources can be configured for the primary cell, but cannot be configured for the secondary cell.
  • Fig. 5 is a diagram illustrating an example 500 associated with performing a BFR, associated with a serving cell of a UE, using a two-step CFRA procedure when BFR resources are configured only for a primary cell of the UE.
  • a UE may detect a beam failure associated with the serving cell of the UE (e.g., a beam failure associated with a beam used for communication with the serving cell) , and may measure, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell (e.g., in a manner similar to that described above in association with Fig. 3) .
  • the serving cell may be the secondary cell or may be the primary cell.
  • the UE may select a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams (e.g., in a manner similar to that described above in association with Fig. 3) .
  • the UE may transmit a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources associated with the primary cell.
  • the communication includes the dedicate preamble associated with the UE, as well as information that identifies the target beam associated with the secondary cell (e.g., an index corresponding to the target beam) .
  • the information that identifies the target beam may be transmitted in a payload of the communication (e.g., in a msgA payload) .
  • the information that identifies the target beam is transmitted in a MAC-CE.
  • the communication may include a dedicate preamble associated with the UE, and the dedicated preamble may be transmitted over a PRACH.
  • the communication may include the information that identifies the target beam, and the information that identifies the target beam may be transmitted over a PUSCH.
  • the UE can transmit the communication using one or more BFR resources, of the set of BFR resources, that do not correspond to the target beam.
  • the UE can select any usable beam in association with performing the BFR.
  • the UE can transmit the communication without waiting for a RACH occasion including BFR resources that correspond to the target beam. For example, since BFR resources are configured only for the primary cell, target beams associated with the secondary cell and target beams associated with the primary cell are mapped to the set of BFR resources associated with the primary cell.
  • the UE need not wait for a RACH occasion corresponding to the target beam in order to transmit the communication, thereby reducing RACH latency and overall latency associated with performing the BFR.
  • the one or more BFR resources in which the communication is transmitted may precede (e.g., in the time domain) one or more other BFR resources, of the set of BFR resources, that correspond to the target beam.
  • the BFR using the two-step CFRA procedure as described in association with Fig. 5 does not require dedicated resources for transmitting the payload including the information that identifies the target beam and, therefore, is not costly in terms of resource usage (e.g., for similar reasons as described in association with Fig. 3) .
  • the network can provide a respective uplink grant to each UE, and each UE can transmit another communication, including the payload, using a set of resources identified by the uplink grant. As such, there is no need for dedicated uplink recourses for transmitting the first communication (i.e., the uplink resources can be shared) .
  • Fig. 5 is provided as an example. Other examples may differ from what is described with respect to Fig. 5.
  • Fig. 6 is a diagram illustrating an example process 600 performed, for example, by a UE, in accordance with various aspects of the present disclosure.
  • Example process 600 is an example where a UE (e.g., UE 120 and/or the like) performs operations associated with beam failure recovery using a two-step CFRA procedure.
  • a UE e.g., UE 120 and/or the like
  • process 600 may include transmitting a communication, associated with performing a BFR procedure, using one or more BFR resources of a set of BFR resources (block 610) .
  • the UE e.g., using transmit processor 264, controller/processor 280, memory 282, and/or the like
  • the communication is associated with transmission of a preamble sequence uniquely associated with the UE, the preamble sequence being transmitted over a physical random access channel (PRACH) .
  • PRACH physical random access channel
  • the communication includes information that identifies a target beam associated with performing the BFR procedure, the information that identifies the target beam being transmitted over a physical uplink shared channel (PUSCH) .
  • PUSCH physical uplink shared channel
  • Process 600 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.
  • the UE may detect a beam failure associated with the UE, and measure, based at least in part on detecting the beam failure, a set of candidate beams. The UE may then select the target beam based at least in part on measuring the set of candidate beams.
  • the UE may determine that the set of BFR resources is configured for an active bandwidth part (BWP) associated with the UE.
  • BWP active bandwidth part
  • the UE may transmit the communication in the one or more BFR resources of the set of BFR resources associated with the active BWP.
  • the UE may determine that no BFR resources are configured for an BWP associated with the UE, and may switch to an initial BWP associated with the UE based at least in part on determining that no BFR resources are configured for the active BWP.
  • the UE may transmit the communication in the one or more BFR resources of the set of BFR resources, the set of resources being configured for the initial BWP.
  • the UE is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell.
  • CA carrier aggregation
  • the BFR may be for a beam failure associated with the secondary cell, and the set of BFR resources is associated with the primary cell.
  • the one or more BFR resources in which the communication is transmitted do not correspond to the target beam.
  • the one or more BFR resources in which the communication is transmitted precede one or more other BFR resources, of the set of BFR resources, that correspond to the target beam.
  • the information that identifies the target beam is transmitted in a medium access control (MAC) control element (CE) .
  • MAC medium access control
  • CE control element
  • the one or more BFR resources include one or more shared physical uplink shared channel (PUSCH) resources.
  • PUSCH physical uplink shared channel
  • process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 6. Additionally, or alternatively, two or more of the blocks of process 600 may be performed in parallel.
  • Fig. 7 is a diagram illustrating an example process 700 performed, for example, by a UE, in accordance with various aspects of the present disclosure.
  • Example process 700 is an example where a UE (e.g., UE 120 and/or the like) performs operations associated with beam failure recovery using a two-step CFRA procedure.
  • a UE e.g., UE 120 and/or the like
  • process 700 may include detecting a beam failure associated with an active BWP of the UE (block 710) .
  • the UE e.g., using receive processor 258, controller/processor 280, memory 282, and/or the like
  • process 700 may include selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams (block 730) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 700 may include determining that a set of BFR resources is configured for the active BWP (block 740) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 700 may include transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of the set of BFR resources configured for the active BWP (block 750) .
  • the UE e.g., using transmit processor 264, controller/processor 280, memory 282, and/or the like
  • the communication is associated with a two-step contention CFRA procedure.
  • the communication includes information that identifies the target beam associated with the active BWP.
  • Process 700 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.
  • the one or more BFR resources in which the communication is transmitted do not correspond to the target beam.
  • the one or more BFR resources in which the communication is transmitted precede one or more other BFR resources, of the set of BFR resources, that correspond to the target beam.
  • the information that identifies the target beam is transmitted in a medium access control (MAC) control element (CE) .
  • MAC medium access control
  • CE control element
  • the UE is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell
  • CA carrier aggregation
  • the one or more BFR resources include one or more shared physical uplink shared channel (PUSCH) resources.
  • PUSCH physical uplink shared channel
  • the UE may receive an uplink grant after transmitting the communication using the one or more BFR resources of the set of BFR resources configured for the active BWP, and may transmit another communication using a set of resources identified by the uplink grant.
  • the other communication includes the information that identifies the target beam associated with the active BWP.
  • process 700 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 7. Additionally, or alternatively, two or more of the blocks of process 700 may be performed in parallel.
  • Fig. 8 is a diagram illustrating an example process 800 performed, for example, by a UE, in accordance with various aspects of the present disclosure.
  • Example process 800 is an example where a UE (e.g., UE 120 and/or the like) performs operations associated with beam failure recovery using a two-step CFRA procedure.
  • a UE e.g., UE 120 and/or the like
  • process 800 may include detecting a beam failure associated with an active BWP of the UE (block 810) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 800 may include measuring, based at least in part on detecting the beam failure, a set of candidate beams configured for the active BWP (block 820) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 800 may include selecting a target beam, associated with the active BWP, based at least in part on measuring the set of candidate beams (block 830) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 800 may include switching to an initial BWP, associated with the UE, based at least in part on determining that no BFR resources are configured for the active BWP (block 840) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 800 may include transmitting a communication, associated with performing a BFR for the active BWP, using one or more BFR resources of a set of BFR resources configured for the initial BWP (block 850) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • the communication is associated with a two-step CFRA procedure.
  • the communication includes information that identifies the target beam associated with the active BWP.
  • Process 800 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.
  • the communication includes information that identifies the active BWP.
  • the information that identifies the target beam further identifies the active BWP.
  • the UE may switch back to the active BWP based at least in part on an indication received from a base station (e.g., base station 110) .
  • a base station e.g., base station 110
  • the UE may select a beam associated with the initial BWP, and may transmit the communication using the selected beam.
  • a transmission configuration indicator (TCI) state is configured on the UE based at least in part on the target beam.
  • the information that identifies the target beam is transmitted in a medium access control (MAC) control element (CE) .
  • MAC medium access control
  • CE control element
  • the UE is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell.
  • CA carrier aggregation
  • the one or more BFR resources include one or more shared physical uplink shared channel (PUSCH) resources.
  • PUSCH physical uplink shared channel
  • the UE may receive an uplink grant after transmitting the communication using the one or more BFR resources of the set of BFR resources configured for the initial BWP, and may transmit another communication using a set of resources identified by the uplink grant.
  • the other communication includes the information that identifies the target beam associated with the active BWP.
  • process 800 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 8. Additionally, or alternatively, two or more of the blocks of process 800 may be performed in parallel.
  • Fig. 9 is a diagram illustrating an example process 900 performed, for example, by a UE, in accordance with various aspects of the present disclosure.
  • Example process 900 is an example where a UE (e.g., UE 120 and/or the like) performs operations associated with beam failure recovery using a two-step CFRA procedure.
  • a UE e.g., UE 120 and/or the like
  • process 900 may include detecting a beam failure associated with a serving cell of the UE (block 910) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • the UE is configured to communicate based at least in a carrier aggregation (CA) configuration associated with a primary cell and a secondary cell, and the serving cell is one of the primary cell or the secondary cell.
  • CA carrier aggregation
  • process 900 may include measuring, based at least in part on detecting the beam failure, a set of candidate beams associated with the serving cell (block 920) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 900 may include selecting a target beam, associated with the serving cell, based at least in part on measuring the set of candidate beams associated with the serving cell (block 930) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • process 900 may include transmitting a communication, associated with performing a BFR associated with the serving cell, using one or more BFR resources of a set of BFR resources associated with a primary cell of the UE (block 940) .
  • the UE e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like
  • the communication is associated with a two-step CFRA procedure.
  • the communication includes information that identifies the target beam associated with the serving cell.
  • Process 900 may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.
  • the one or more BFR resources in which the communication is transmitted do not correspond to the target beam.
  • the one or more BFR resources in which the communication is transmitted precede one or more other BFR resources, of the set of BFR resources, that correspond to the target beam.
  • the one or more BFR resources include one or more shared physical uplink shared channel (PUSCH) resources.
  • PUSCH physical uplink shared channel
  • Fig. 10 is a diagram illustrating an example process 1000 performed, for example, by a base station, in accordance with various aspects of the present disclosure.
  • Example process 1000 is an example where a base station (e.g., base station 110 and/or the like) performs operations associated with BFR using a two-step CFRA procedure.
  • a base station e.g., base station 110 and/or the like
  • process 1000 may include receiving a communication, associated with a BFR procedure, in one or more BFR resources of a set of BFR resources (block 1010) .
  • the base station e.g., using receive processor 238, controller/processor 240, memory 242, and/or the like
  • the communication is associated with transmission of a preamble sequence uniquely associated with a UE (e.g., UE 120) , the preamble sequence being received over a PRACH.
  • the communication includes information that identifies a target beam associated with the BFR procedure, the information that identifies the target beam being received over a PUSCH.
  • the information that identifies the target beam is received in a medium access control (MAC) control element (CE) .
  • MAC medium access control
  • CE control element
  • TCI transmission configuration indicator
  • the base station may configure the TCI state on the UE without performing a beam management procedure associated with the UE.
  • the one or more BFR resources include one or more shared physical uplink shared channel (PUSCH) resources.
  • PUSCH physical uplink shared channel
  • process 1000 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 10. Additionally, or alternatively, two or more of the blocks of process 1000 may be performed in parallel.
  • ком ⁇ онент is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software.
  • a processor is implemented in hardware, firmware, and/or a combination of hardware and software.
  • satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.
  • “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .
  • the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
  • ⁇ Rel-16 will support two-step RACH, which consists of only two steps instead of four steps in the traditional contention-based RACH (CBRA) procedure
  • ⁇ msgA transmission which includes both a preamble and PUSCH payload
  • UE can include RRC Reconfiguration Complete message and/or other additional information in the payload of msgA to speed up the handover procedure. So there are benefits (ie latency reduction) for using two-step CFRA for handover
  • UE can also include extra information in msgA payload to help reduce the overall latency of a BFR procedure.
  • ⁇ NW can choose to configure dedicated resources for BFR
  • Each RACH occasion in this dedicated PRACH configuration corresponds to one of the reference beams configured for the UE
  • ⁇ Set of reference beams for UE is defined on a per BWP basis
  • Each US is also configured with a dedicated preamble which represents UE
  • UE After beam failure is detected, UE first decides in which BWP to perform BFR
  • ⁇ UE selects a desired beam as its new serving beam from the set of reference beams configured for the BWP in which it performs BWP
  • ⁇ UE then transmits its dedicated preamble in the RACH occasion corresponds to the selected beam (the new target beam)
  • ⁇ UE then monitors BFR search space on PDCCH for any message addresses to its C-RNTI
  • ⁇ RACH part of BFR is complete if UE receives a PDCCH msg that meets the above criteria
  • ⁇ NW will reconfigure UE’s TCI state based on the new reference beam indicated by UE during BFR procedure
  • ⁇ UE does not need to perform BWP switch to initial BWP to perform BFR
  • UE may have to wait a long time before the first RACH occasion associated with its target reference beam comes up
  • This index can be sent in a MAC CE
  • ⁇ Active BWP can be a wide BWP located in a different frequency band as the initial BWP
  • active BWP may be configured with CSI-RS while initial BWP has only SSB configured
  • UE has to perform the following:
  • wide BWPs use wide-band CSI-RS (narrow beam) as reference beams
  • ⁇ Network therefore needs to perform beam management procedure for UE to refine its beams based on CSI-RS
  • ⁇ UE performs measurement on reference beams in the current active BWP and select a target beam configured for that BWP for recovery
  • the PUSCH payload in its msgA includes the index of its target beam in the active BWP
  • this index can be sent in a MAC CE
  • ⁇ UE selects a suitable reference beam configured for initial BWP to send its msgA
  • ⁇ “Suitable” good enough for UE to send msgA to network
  • this selected beam does not have to be, or related to, UE’s target beam for recovery
  • ⁇ NW can switch UE back to the active BWP
  • ⁇ NW can directly configure UE’s new TCI states based on the target reference beam indicated by UE in its msgA PUSCH payload.
  • FR1 cells have up to 8 beams
  • FR2 cells have up to 64 beams
  • Both PCell and (some) SCells can be configured with BFR resources (not supported in Rel-15)
  • BFR resource will have long PRACH configuration period (can have up to 8+64 beams)
  • UE performs measurements on candidate beams and select a new target beam for recovery
  • PRACH configuration period for BFR on PCell can be very short, which enables low RACH latency
  • ⁇ BFR does not happen often. And it is even rarer that multiple UEs have beam failures at the same time
  • Each UE still has its dedicated preamble and RACH occasions as in regular CFRA BFR
  • UE’s dedicated preamble indicates its identity. So network has no problem identify which UE is the TB sent over the shared PUSCH resource for
  • network can provide a UL grant to UE.
  • UE then sends network its msg A payload over this dedicated UL grant to network

Abstract

Divers aspects de la présente invention se rapportent d'une manière générale aux communications sans fil. Selon certains aspects, un équipement utilisateur (UE) peut transmettre une communication, associée à la réalisation d'une procédure de rétablissement après défaillance de faisceau (BFR), à l'aide d'une ou plusieurs ressources BFR d'un ensemble de ressources BFR. La communication peut être associée à la transmission d'une séquence de préambule associée uniquement à l'UE, la séquence de préambule étant transmise sur un canal physique d'accès aléatoire (PRACH), et peut comprendre des informations qui identifient un faisceau cible associé à la réalisation de la procédure BFR, lesdites informations étant transmises sur un canal physique partagé de liaison montante (PUSCH). L'invention porte en outre sur de nombreux autres aspects.
PCT/CN2019/085403 2019-05-02 2019-05-02 Rétablissement après défaillance de faisceau au moyen d'une procédure de canal d'accès aléatoire sans contention en deux étapes WO2020220372A1 (fr)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
US20180278467A1 (en) * 2017-03-22 2018-09-27 Qualcomm Incorporated Beam failure identification and recovery techniques
US20190074891A1 (en) * 2017-09-07 2019-03-07 Futurewei Technologies, Inc. Apparatus and method for beam failure recovery
WO2019050380A1 (fr) * 2017-09-11 2019-03-14 엘지전자 주식회사 Procédé de récupération de faisceau dans un système de communication sans fil, et dispositif associé
EP3461026A1 (fr) * 2017-09-22 2019-03-27 ASUSTek Computer Inc. Procédé et appareil de prévention d'erreur d'alignement de la partie de largeur de bande dans un système de communication sans fil

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
US20180278467A1 (en) * 2017-03-22 2018-09-27 Qualcomm Incorporated Beam failure identification and recovery techniques
US20190074891A1 (en) * 2017-09-07 2019-03-07 Futurewei Technologies, Inc. Apparatus and method for beam failure recovery
WO2019050380A1 (fr) * 2017-09-11 2019-03-14 엘지전자 주식회사 Procédé de récupération de faisceau dans un système de communication sans fil, et dispositif associé
EP3461026A1 (fr) * 2017-09-22 2019-03-27 ASUSTek Computer Inc. Procédé et appareil de prévention d'erreur d'alignement de la partie de largeur de bande dans un système de communication sans fil

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QUALCOMM INCORPORATED: "Beam recovery procedure", 3GPP DRAFT; R1-1713402, 25 August 2017 (2017-08-25), Prague, CZ, pages 1 - 5, XP051316206 *

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