Response for TRP specific BFRQ and beam reset

Certain aspects of the present disclosure provide enhancements to enable per transmission reception point (per-TRP or per beam group) based beam failure recovery (BFR), and more particularly, techniques for configuring physical uplink control channel (PUCCH) BFR for TRP specific BFR. A method that may be performed by a user equipment (UE) includes communicating using beams associated with at least two beam groups, transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group, and receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to beam failure recovery (BFR).

Description of Related Art

SUMMARY

Certain aspects of the disclosure are directed to a method of wireless communication by a user equipment (UE). In some examples, the method includes communicating using beams associated with at least two beam groups. In some examples, the method includes transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. In some examples, the method includes receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

Certain aspects of the disclosure are directed to a method of wireless communication by a transmission reception point (TRP). In some examples, the method includes receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected. In some examples, the method includes transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received.

Certain aspects of the disclosure are directed to a user equipment (UE) configured for wireless communication. The UE includes a memory and a processor coupled to the memory. In some examples, the processor and the memory are configured to communicate using beams associated with at least two beam groups. In some examples, the processor and the memory are configured to transmit a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. In some examples, the processor and the memory are configured to receive a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

Certain aspects of the disclosure are directed to a transmission reception point (TRP) for wireless communication. The TRP includes a memory and a processor coupled to the memory. In some examples, the processor and the memory are configured to receive, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected. In some examples, the processor and the memory are configured to transmit a response to the BFRQ based, at least in part, on how the BFRQ is received.

Certain aspects of the disclosure are directed to a user equipment (UE). In some examples, the UE includes means for communicating using beams associated with at least two beam groups. In some examples, the method includes transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. In some examples, the UE includes means for receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

Certain aspects of the disclosure are directed to a transmission reception point (TRP). In some examples, the TRP includes means for receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected. In some examples, the TRP includes means for transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received.

Certain aspects of the disclosure are directed to a non-transitory computer-readable medium having instructions stored thereon that, when executed by a UE, cause the UE to perform operations. In some examples, the operations include communicating using beams associated with at least two beam groups. In some examples, the operations include transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. In some examples, the operations include receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

Certain aspects of the disclosure are directed to a non-transitory computer-readable medium having instructions stored thereon that, when executed by a TRP, cause the TRP to perform operations. In some examples, the operations include receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected. In some examples, the operations include transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received.

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a UE. The method generally includes communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs, detecting a beam failure in a first one of the beam groups, transmitting a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected, and monitoring for a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a network entity. The method generally includes receiving, from a user equipment, a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected and sending a response to the BFRQ based, at least in part, on how the BFRQ is received.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for techniques enabling per-transmission reception point (per-TRP) or per beam group based beam failure recovery (BFR) procedures. More specifically, the techniques may involve the configuration of physical uplink control channel (PUCCH) beam failure recovery (BFR) for transmission reception point (TRP) specific BFR. While the techniques may involve beam groups, they may be considered TRP-specific. This is because the concept of TRPs may generally be kept transparent to a UE. In other words, the UE may only be aware of a beam group (for a set of beams) corresponding to a TRP (but may be unaware of the actual corresponding TRP ID). Thus, certain aspects are directed to providing the UE with an indication that a beam failure recovery request (BFRQ) for a particular beam group is successful and, hence, the UE may stop further BFRQ attempts for that beam group. Such signaling may enhance wireless communication by reducing unnecessary transmissions, thereby preserving air interface resources and processing resources. In certain aspects, a TRP may itself be a base station (BS), or each TRP may be a radio head (RH) for a base station, where a BS may have multiple RHs.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or new radio (e.g., 5G new radio (NR)) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe. NR supports beamforming and beam direction may be dynamically configured. Multiple-input multiple-output (MIMO) transmissions with precoding may also be supported. MIMO configurations in a downlink may support up to 8 transmit antennas with multi-layer downlink transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

FIG.1illustrates an example wireless communication network100in which aspects of the present disclosure may be performed. For example, the wireless communication network100may include a UE120a(with a beam manager122) that is configured to perform operations1200ofFIG.12and operations1600ofFIG.16. Similarly, the wireless communication network100may include a network entity, such as base station (BS)110a(with a beam manager112) that is configured to perform operations1300ofFIG.13.

As shown inFIG.1, the wireless communication network100may be in communication with a core network (CN)132, including one or more CN nodes134. The core network132may in communication with one or more base station (BSs)110a-z(each also individually referred to herein as BS110or collectively as BSs110) and/or user equipment (UE)120a-y(each also individually referred to herein as UE120or collectively as UEs120) in the wireless communication network100via one or more interfaces.

The BSs110communicate with UEs120in the wireless communication network100. The UEs120(e.g.,120x,120y, etc.) may be dispersed throughout the wireless communication network100, and each UE120may be stationary or mobile. Wireless communication network100may also include relay stations (e.g., relay station110r), also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS110aor a UE120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE120or a BS110), or that relays transmissions between UEs120, to facilitate communication between devices.

A network controller130may be in communication with a set of BSs110and provide coordination and control for these BSs110(e.g., via a backhaul). In aspects, the network controller130may be in communication with a core network132(e.g., a 5G Core Network (5GC)), which provides various network functions such as Access and Mobility Management, Session Management, User Plane Function, Policy Control Function, Authentication Server Function, Unified Data Management, Application Function, Network Exposure Function, Network Repository Function, Network Slice Selection Function, etc.

FIG.2illustrates example components of a BS110aand a UE120a(e.g., in the wireless communication network100ofFIG.1).

At the BS110a, a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

The memories242and282may store data and program codes for BS110aand UE120a, respectively. A scheduler244may schedule UEs for data transmission on the downlink and/or uplink.

Antennas252, processors266,258,264, and/or controller/processor280of the UE120aand/or antennas234, processors220,230,238, and/or controller/processor240of the BS110amay be used to perform the various techniques and methods described herein. For example, as shown inFIG.2, the controller/processor240of the BS110ahas a beam manager112that configures PUCCH-BFR for TRP specific (or beam group specific) BFR, according to aspects described herein. As shown inFIG.2, the controller/processor280of the UE120ahas a beam manager122that configures PUCCH-BFR for TRP specific (or beam group specific) BFR, according to aspects described herein. Although shown at the controller/processor, other components of the UE120aand BS110amay be used to perform the operations described herein.

FIG.3is a diagram showing an example of a frame format300for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots (e.g., 1, 2, 4, 8, 16, . . . slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., 7, 12, or 14 symbols) depending on the SCS. The symbol periods in each slot may be assigned indices. A sub-slot structure may refer to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols). Each symbol in a slot may be configured for a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.

In NR, a synchronization signal block (SSB) is transmitted. In certain aspects, SSBs may be transmitted in a burst where each SSB in the burst corresponds to a different beam direction for UE-side beam management (e.g., including beam selection and/or beam refinement). The SSB includes a PSS, a SSS, and a two symbol PBCH. The SSB can be transmitted in a fixed slot location, such as the symbols0-3as shown inFIG.3. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SSBs may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI), system information blocks (SIBs), other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes. The SSB can be transmitted up to sixty-four times, for example, with up to sixty-four different beam directions for mmWave. The multiple transmissions of the SSB are referred to as a SS burst set. SSBs in an SS burst set may be transmitted in the same frequency region, while SSBs in different SS bursts sets can be transmitted at different frequency regions.

Further system information such as, remaining minimum system information (RMSI), system information blocks (SIBs), other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes.

As shown inFIG.4, the SS blocks may be organized into SS burst sets to support beam sweeping. As shown, each SSB within a burst set may be transmitted using a different beam, which may help a UE quickly acquire both transmit (Tx) and receive (Rx) beams (e.g., in certain mmW applications). A physical cell identity (PCI) may still be decoded from the PSS and SSS of the SSB.

Certain deployment scenarios may include one or both NR deployment options. Some may be configured for non-standalone (NSA) and/or standalone (SA) option. A standalone cell may need to broadcast both SSB and remaining minimum system information (RMSI), for example, with SIB1 and SIB2. A non-standalone cell may only need to broadcast SSB, without broadcasting RMSI. In a single carrier in NR, multiple SSBs may be sent in different frequencies, and may include the different types of SSB.

Control Resource Sets (CORESETs)

A control resource set (CORESET) for an OFDMA system (e.g., a communications system transmitting PDCCH using OFDMA waveforms) may comprise one or more control resource (e.g., time and frequency resources) sets, configured for conveying PDCCH, within the system bandwidth (e.g., a specific area on the NR downlink resource grid) and a set of parameters used to carry PDCCH/DCI. For example, a CORESET may be similar in area to an LTE PDCCH area (e.g., the first 4 OFDM symbols in a subframe).

Within each CORESET, one or more search spaces (e.g., common search space (CSS), UE-specific search space (USS), etc.) may be defined for a given UE. Search spaces are generally areas or portions where a communication device (e.g., a UE) may look for control information.

According to aspects of the present disclosure, a CORESET is a set of time and frequency domain resources, defined in units of resource element groups (REGs). Each REG may comprise a fixed number (e.g., twelve) tones/subcarriers in one symbol period (e.g., a symbol period of a slot), where one tone in one symbol period is referred to as a resource element (RE). A fixed number of REGs, such as six, may be included in a control channel element (CCE). Sets of CCEs may be used to transmit new radio PDCCHs (NR-PDCCHs), with different numbers of CCEs in the sets used to transmit NR-PDCCHs using differing aggregation levels. Multiple sets of CCEs may be defined as search spaces for UEs, and thus a NodeB or other base station may transmit an NR-PDCCH to a UE by transmitting the NR-PDCCH in a set of CCEs that is defined as a decoding candidate within a search space for the UE. The UE may receive the NR-PDCCH by searching in search spaces for the UE and decoding the NR-PDCCH transmitted by the NodeB.

As noted above, different aggregation levels may be used to transmit sets of CCEs. Aggregation levels may be generally defined as the number of CCEs that include a PDCCH candidate and may include aggregation levels 1, 2, 4, 8, and 18, which may be configured by a radio resource control (RRC) configuration of a search space set (SS-set). A CORESET may be linked with the SS-set within the RRC configuration. For each aggregation level, the number of PDCCH candidates may be RRC configurable.

Operating characteristics of a NodeB or other base station in an NR communications system may be dependent on a frequency range (FR) in which the system operates. A frequency range may comprise one or more operating bands (e.g., “n1” band, “n2” band, “n7” band, and “n41” band), and a communications system (e.g., one or more NodeBs and UEs) may operate in one or more operating bands. Frequency ranges and operating bands are described in more detail in “Base Station (BS) radio transmission and reception” TS38.104 (Release 15), which is available from the 3GPP website.

As described above, a CORESET is a set of time and frequency domain resources. The CORESET can be configured for conveying PDCCH within system bandwidth. A UE may determine a CORESET and monitor the CORESET for control channels. During initial access, a UE may identify an initial CORESET (CORESET #0) configuration from a field (e.g., pdcchConfigSIB1) in a maser information block (MIB). This initial CORESET may then be used to configure the UE, such as with other CORESETs and/or bandwidth parts via dedicated (e.g., UE-specific) signaling. When the UE detects a control channel in the CORESET, the UE attempts to decode the control channel and communicates with the transmitting BS (e.g., the transmitting cell) according to the control data provided in the control channel (e.g., transmitted via the CORESET).

In some cases, CORESET #0 may include different numbers of resource blocks (RBs). For example, in some cases, CORESET #0 may include one of 24, 48, or 96 RBs. For other CORESETSs, a 45-bit bitmap may be used to configure available RB-groups, where each bit in the bitmap is with respect to 6-RBs within a bandwidth part (BWP) and a most significant bit corresponds to the first RB-group in the BWP.

According to aspects of the present disclosure, when a UE is connected to a cell (or BS), the UE may receive a master information block (MIB). The MIB can be in a synchronization signal and physical broadcast channel (SS/PBCH) block (e.g., in the PBCH of the SS/PBCH block) on a synchronization raster (sync raster). In some scenarios, the sync raster may correspond to an SSB. From the frequency of the sync raster, the UE may determine an operating band of the cell. Based on a cell's operation band, the UE may determine a minimum channel bandwidth and a subcarrier spacing (SCS) of the channel. The UE may then determine an index from the MIB (e.g., four bits in the MIB, conveying an index in a range 0-15).

Given this index, the UE may look up or locate a CORESET configuration (this initial CORESET configured via the MIB is generally referred to as CORESET #0). This may be accomplished from one or more tables of CORESET configurations. These configurations (including single table scenarios) may include various subsets of indices indicating valid CORESET configurations for various combinations of minimum channel bandwidth and subcarrier spacing (SCS). In some arrangements, each combination of minimum channel bandwidth and SCS may be mapped to a subset of indices in the table.

Alternatively, or additionally, the UE may select a search space CORESET configuration table from several tables of CORESET configurations. These configurations can be based on a minimum channel bandwidth and SCS. The UE may then look up a CORESET configuration (e.g., a Type0-PDCCH search space CORESET configuration) from the selected table, based on the index. After determining the CORESET configuration (e.g., from the single table or the selected table), the UE may then determine the CORESET to be monitored (as mentioned above) based on the location (in time and frequency) of the SS/PBCH block and the CORESET configuration.

FIG.5shows an exemplary transmission resource mapping500, according to aspects of the present disclosure. In the exemplary mapping, a BS (e.g., BS110a, shown inFIG.1) transmits an SS/PBCH block502. The SS/PBCH block includes a MIB conveying an index to a table that relates the time and frequency resources of the CORESET504to the time and frequency resources of the SS/PBCH block.

The BS may also transmit control signaling. In some scenarios, the BS may also transmit a PDCCH to a UE (e.g., UE120, shown inFIG.1) in the (time/frequency resources of the) CORESET. The PDCCH may schedule a PDSCH506. The BS then transmits the PDSCH to the UE. The UE may receive the MIB in the SS/PBCH block, determine the index, look up a CORESET configuration based on the index, and determine the CORESET from the CORESET configuration and the SS/PBCH block. The UE may then monitor the CORESET, decode the PDCCH in the CORESET, and receive the PDSCH that was allocated by the PDCCH.

Different CORESET configurations may have different parameters that define a corresponding CORESET. For example, each configuration may indicate a number of resource blocks (e.g., 24, 48, or 96), a number of symbols (e.g., 1-3), and/or an offset (e.g., 0-38 RBs) that indicates a location in frequency.

Further, REG bundles may be used to convey CORESETs. REGs in an REG bundle may be contiguous in a frequency and/or a time domain. In certain cases, the time domain may be prioritized before the frequency domain. REG bundle sizes may include, for example: 2, 3, or 6 for interleaved mapping and 6 for non-interleaved mapping.

As noted above, sets of CCEs may be used to transmit new radio PDCCHs (NR-PDCCHs), with different numbers of CCEs in the sets used to transmit NR-PDCCHs using differing aggregation levels.

Example Multi-TRP Beam Failure Recovery (BFR)

As mentioned above, aspects of the present disclosure relate generally to beam failure detection and recovery. In some systems, narrow-beam transmission and reception is useful for improving the link budget at millimeter-wave (mmW) frequencies but may be susceptible to beam failure. In mmW, directional beamforming is used between the UE and a BS, and the UE and BS communicate via a beam pair link (BPL). Though certain aspects may be described with respect to mmW frequency, such aspects may also be applicable to other suitable frequencies.

A beam failure generally refers to a scenario in which the quality of a beam falls below a threshold, which may lead to radio link failure (RLF). In response to RLF, a UE may perform a cell reselection process, wherein the UE may use neighbor BS information acquired from a decoded neighbor advertisement message, or may schedule scanning/sleep intervals to scan for neighbor base stations for the purpose of handover to a potential target BS. To avoid cell reselection, the UE may use a faster procedure using lower layer signaling within the same cell to recover from beam failure, referred to as beam recovery. For example, instead of initiating a cell reselection when a beam pair link quality becomes too low, a beam pair reselection within the same cell can be performed. Relatively speaking, beam pair reselection requires less time and fewer processing resources compared to cell reselection.

Beam failure may be detected by monitoring a beam failure detection (BFD) reference signal (RS) and assessing if a beam failure trigger condition has been met. Generally, a UE monitors the BFD RS from a primary cell (Pcell), a primary secondary cell (PScell), or a secondary cell (Scell) (e.g., coverage area of a BS). In some examples, beam failure detection is triggered if an estimated block error rate (BLER) of reference signals associated with a configured control resource set (CORESET) is above a threshold (e.g., 10%). In some examples, the UE detects beam failure when the reference signal receive power (RSRP) or other signal quality measurement (based on the BFD RS) of a BPL fails to satisfy (e.g., is below) a threshold. Once beam failure is detected, the UE initiates beam failure recovery (BFR).

In some examples, a BFR procedure may include candidate beam detection (CBD), whereby a UE may detect and measure candidate beams within a cell for beam recovery. Through CBD measurements, a UE can report a good beam to a TRP upon detection of a beam failure. In a multi-TRP scenario, for BFR, the UE may be configured to provide per-TRP BFR, which enables separate BFD and separate CBD for the beams corresponding to a TRP in a component carrier (CC) that is configured with two values of CORESET pool indices. For example, the TRP may employ carrier aggregation (CA) to provide sufficient bandwidth to support high data rate communications. Such a CA system may combine bandwidth from distinct frequency bands, with each referred to as a CC. In some examples, the UE and TRP may use multiple CCs, each of which may be scheduled independent of the others. For example, a separate CC may be used for downlink control information (DCI), downlink data, uplink control information (UCI), and uplink data, and each may be scheduled independent of the others.

In the absence of per-TRP BFR, BFD and CBD may not be triggered until all beams in that CC become weak. With per-TRP BFR, when beams for a given TRP become weak, beam recovery procedures can be performed and a suitable (e.g., best, a beam above a threshold, etc.) beam corresponding to that TRP can be identified without having to wait for the beams of the other TRP to also become weak, and thus reliability and communications efficiency can be enhanced.

FIGS.6and7illustrate examples of a wireless communication system700that supports BFR for a multi-TRP in a PCell, PScell, or Scell, in accordance with aspects of the present disclosure.

In some examples, a multi-TRP operation wireless communication system700may include a UE120, and a number of TRPs704a-bassociated with PCell/PScell/Scell, which may be examples of the corresponding devices described herein. TRPs704a-bmay, in this example, provide a multi-TRP PCell/PScell/Scell in which a first beam of a first TRP704aand a second beam of a second TRP704bprovide communications with the UE120.

As shown inFIG.6, in some examples, the multi-TRP transmissions may be configured based on a single downlink control information (DCI) communication, in which the DCI (e.g., transmitted in physical downlink control channel (PDCCH)706from first TRP704a) schedules a downlink shared channel transmission; PDSCH—layer 1708transmitted from first TRP704avia the first beam and PDSCH—layer 2710transmitted from second TRP704bvia the second beam. Configuration based on a single DCI communication may allow different TRPs (e.g., first TRP704aand second TRP704b) to transmit different spatial layers in overlapping resource blocks (RBs)/symbols. In some examples, different TRPs704may transmit different resource blocks multiplexed on a downlink carrier using frequency division multiplexing (FDM) techniques or different orthogonal frequency division multiplexing (OFDM) symbols multiplexed on a downlink carrier using time division multiplexing (TDM) techniques. Multi-TRP operation configured based on a single DCI communication may result in ideal backhaul or backhaul with a small delay.

As shown inFIG.7, in some examples, the multi-TRP transmissions may be configured based on multiple downlink control information (DCI) communications, in which a first DCI (e.g., transmitted in PDCCH1712from first TRP704a) schedules a downlink shared channel transmission (e.g., PDSCH1716transmitted from first TRP704avia the first beam), and a second DCI (e.g., transmitted in PDCCH2714from second TRP704b) schedules a second downlink shared channel transmission (e.g., PDSCH2718transmitted from second TRP704bvia the second beam). In some examples, one or more of the first TRP704aor the second TRP704bmay transmit a CORESET configuration indicating different values of a “CORESETPoolIndex” parameter, providing the UE102with different CORESET groups/multiple CORESET groups. In some examples, the CORESETPoolIndex parameter may be different for each TRP704. Thus, TRP704differentiation at the UE120, in some cases, may be based on a value of the CORESET pool index, where each CORESET (e.g., up to a maximum of five CORESETs) can be configured with a value of CORESET pool index. To support multiple PDCCH monitoring as shown inFIG.7, for example, up to a maximum of five CORESETs can be configured with up to three CORESETs per TRP.

As shown inFIG.8, in some examples, the UE may be configured by a higher layer parameter PDCCH-Config (e.g., a condition in 3GPP specification used to determine whether UE120is configured with multi-DCI based multi-TRP) which contains two different values of CORESETPoolIndex in CORESETs for the active bandwidth part (BWP) of a serving cell. In some examples, the value of CORESET pool index may be zero (0)802or one (1)804, which groups the CORESETs into two groups, which may correspond to the different TRPs704. Beyond the CORESET pool index distinction, the UE120is oblivious to differences beyond identifying that different TRPs are used within the wireless communication system. Only some CCs may be configured with two values of CORESET pool index, while other CCs may not be configured with two values of CORESET pool index and thus BFD/BFR for on a per-TRP704basis may be provided for CCs that are configured with two values of CORESET pool index.

In the non-limiting example shown inFIG.7, PCell/PSCell/SCell may be configured with two values of CORESET pool index, with one value associated with the first TRP704aand a second value associated with second TRP704b. In this case, each TRP704may transmit one or more BFD reference signals that may be monitored by the UE120. In this example, the UE120may determine that a first beam of a first CORESET pool index value (e.g., CORESETPoolIndex=0) has a channel metric (e.g., a reference signal received power RSRP)) that is below a threshold value (e.g., when radio link quality is worse than a threshold (e.g., Qout) for all the reference signals in BFD resources that are associated with the first CORESET pool index value). In this example, Qout may be defined as a level at which the downlink radio level link of a given resource configuration cannot be reliably received.

Accordingly, a UE may be configured for a carrier (e.g., an individual CC, bandwidth part (BWP), and the like) associated with Pcell/Pscell/Scell that is configured with the first CORESET pool index value (e.g., CORESETPoolIndex=0) and a second CORESET pool index value (e.g., CORESETPoolIndex=1). The first CORESET pool index value may be associated with the first TRP704aof Pcell/Pscell/Scell and the second CORESET pool index value may be associated with the second TRP704bof Pcell/Pscell/Scell. Each TRP704may transmit one or more BFD reference signals that are associated with their respective value of CORESET pool index. This may include two sets of BFD reference signals (e.g., failureDetectionResources) being configured, with each set corresponding to a different value of CORESET pool index. In another example this may include each reference signal (e.g., each resource within failureDetectionResources) being configured with a CORESET pool index value. If the resource is not configured with a CORESET pool index value, it may be considered associated with CORESET pool index value 0 (e.g., the first CORESET pool index value). Additionally, a resource may be configured with both values of CORESET pool indices. When the reference signals (e.g., failureDetectionResources) are not configured, the reference signal sets indicated in the active transmission configuration indicator (TCI) states of CORESETS configured with CORESET pool index value=0/1 (e.g., either CORESET pool index value) may determine the first/second set of resources, respectively. BFD for a value of CORESET pool index may be declared when the radio link quality is worse than Qout for all the reference signals and the BFD resources that are associated with that CORESET pool index value.

UE120may also receive or otherwise identify an indication of a set of candidate beams available for a BFR procedure. The set of candidate beams may include a first subset of candidate beams associated with the first CORESET pool index value and a second subset of candidate beams associated with the second CORESET pool index value. In one example, this may include two lists of candidate beams (e.g., candidateBeamRSList) being configured, each corresponding to a CORESET pool index value. In this example, each candidateBeamRSList may include a list of reference signals (e.g., CSI-RS, SSB, etc.) identifying the candidate beams for recovery and any associated random access parameters. That is, UE120may be separately configured with the first subset of candidate beams associated with the first CORESET pool index value and the second subset of candidate beams associated with the second CORESET pool index value.

UE120may detect or otherwise determine that a beam failure has occurred (e.g., the RSRP on the active beam is less than Qout) on the carrier of the active beam (e.g., either the first beam or the second beam) of Pcell/Pscell/Scell. UE120may, based on the detected beam failure, select a new candidate beam from the set of candidate beams based on monitoring a resource (e.g., CBD resources) associated with the first CORESET pool index value or the second CORESET pool index value. When BFD is declared for a value of CORESET pool index, a new candidate beam (e.g., identified by reference signal index/ID “Qnew”) may be identified from within the candidate reference signals associated with the same value of CORESET pool index. Accordingly, UE120may select a new candidate beam from the set of candidate beams based on monitoring a resource (e.g., CBD resource(s)) associated with the first CORESET pool index value when the first beam experiences beam failure or the second CORESET pool index value when the second beam experiences beam failure. UE120may transmit or otherwise convey an access message to Pcell/Pscell/Scell (e.g., via the first TRP704aif the conditions on the carrier permit and/or via the second TRP704b) indicating the new candidate beam during the BFR procedure.

In some aspects, UE120may receive or otherwise identify a first subset of random access resources (e.g., RACH resources/random access preamble indices) associated with the first subset of candidate beam detection (e.g., CBD) resources corresponding to the first subset of candidate beams and a second subset of random access resources associated with a second subset of CBD resources corresponding to the second subset of candidate beams. That is, dedicated RACH resources for BFR may also be associated with the value of the CORESET pool index. In some examples, this may include an implicit indication based on an association of a RACH resource/random access preamble index with a candidate beam reference signal (e.g., as each candidate beam reference signal is already associated with a value of a CORESET pool index). The network (e.g., Pcell/Pscell/Scell) may determine which TRP/CORESET pool index value has experienced a beam failure in the Pcell/Pscell/Scell based on the resource/random access preamble index of the received RACH (e.g., based on the random access resource used for transmitting the access message).

In some examples this may include two lists of RACH resources/random access preamble indices being configured, with each list of RACH resource/random access preamble index being associated with one of the CORESET pool index values. For example, UE120may receive an indication of a first set of random access resources associated with the first CORESET pool index value and a second set of random access resources associated with the second CORESET pool index value. Accordingly, UE120may determine that the new candidate beam is associated with the first subset of candidate beams and select a random access resource from the first set of random access resources corresponding to the new candidate beam to transmit the access message. In another example, UE120may determine that the new candidate beam is associated with the second subset of candidate beams and select a random access resource from the second set of random access resources corresponding to the new candidate beam to transmit the access message.

In some examples, this may include updating various quasi-colocation (QCL) relationships. For example, two antenna ports are said to be QCL'd if properties of a channel over which a first symbol on one antenna port is conveyed can be inferred from another channel over which a second symbol on another antenna port is conveyed. That is, if the first symbol is QCL'd with the second symbol, then channel information estimated to detect the second symbol may be used to detect the first symbol as well.

For example, UE120may determine that the new candidate beam is associated with the first CORESET pool index value and, therefore, update the QCL relationship for a CORESET with index 0 (e.g., the CORESET that is used for common search space procedures). The updated QCL relationship may correspond to the QCL configuration of the new candidate beam. That is, when the new candidate beam (e.g., corresponding to reference signal index Qnew) corresponds to CORESET pool index value 0, the QCL assumptions for CORESET 0 may be updated (e.g., after 28 symbols after the last symbol carrying PDCCH). Accordingly, the updated QCL configuration may occur after a threshold time period. The QCL assumption (e.g., QCL configuration) for CORESET 0 may not be updated when the new candidate beam corresponds to CORESET pool index value 1 (e.g., the second CORESET pool index value). In some examples, this may be based on CORESET 0 being typically associated with CORESET pool index value 0.

In some examples, this may include UE120determining that the new candidate beam is associated with the first or second CORESET pool index values. Accordingly, UE120may update the QCL relationship for each CORESET associated with the first CORESET pool index value or second CORESET pool index value, respectively. Again, the updated QCL relationship may correspond to the QCL configuration of the new candidate beam. That is, when the new candidate beam corresponds to either CORESET pool index value, the QCL assumption for all CORESETS associated with the same value of CORESET pool index may be reset to the new candidate beam (e.g., 28 symbols after the last symbol carrying PDCCH). The set of activated TCI states for a PDSCH that correspond to the same value of CORESET pool index may be reset to the new candidate beam. Accordingly, UE120may update the activated set of TCI states for a data channel to a TCI state of the new candidate beam.

In some aspects, this may include UE120determining that the new candidate beam is associated with the first or second CORESET pool index value. UE120may update the CORESET pool index value of a common CORESET accordingly. For example, UE120may update the CORESET pool index value of the common CORESET to correspond to the CORESET pool index value of the new candidate beam. That is, when the new candidate beam corresponds to the first or second CORESET pool index value and one CORESET (e.g., the common CORESET) is configured for BFR, the CORESET pool index value of the CORESET that is associated with recovery search space ID(s) (e.g., recoverySearchSpaceId(s)) may be reset to the CORESET pool index value that the new candidate beam corresponds to.

In some examples, UE120may treat the second CORESET pool index value (e.g., CORESETPoolIndex=1) as an SCell for the BFR procedure. That is, UE120may determine that the beam failure on the active beam of PCell is associated with the first CORESET pool index value (e.g., CORESETPoolIndex=0 and is associated with the first TRP215-a) and, therefore, perform a PCell BFR procedure. When BFD is detected for the first CORESET pool index value (e.g., CORESETPoolIndex=0), the procedures corresponding to a PCell BFR procedure may be followed (e.g., RACH transmission, PDCCH reception in a recovery search ID, etc., as is generally described with reference to operations1300ofFIG.13). However, UE120may determine that the beam failure on the active beam of PCell is associated with the second CORESET pool index value (e.g., CORESETPoolIndex=1 and is associated with the second TRP215-b) and, therefore, perform a SCell BFR procedure. If BFD is detected for the second CORESET pool index value (e.g., CORESETPoolIndex=1) for PCell, the procedures corresponding to an SCell BFR procedure may be followed. For example, a link recovery request (LRR) message may be transmitted in a configured PUCCH resource, and a grant scheduling an uplink transmission for UE120may be received in response. In this situation, the medium access control (MAC) control element (CE) beam failure response may convey an indication of an additional Ci field and corresponding AC/candidate reference signal ID fields (e.g., when Ci=1) associated with the CORESET pool index value 1 in the PCell. The AC field may correspond to the candidate reference signal ID field.

Examples of beam failure declaration, candidate beam detection, beam recovery, and the like, are discussed with referenceFIG.9which generally illustrates a PCell BFR procedure andFIG.10which generally illustrates an SCell BFR procedure.

FIG.9illustrates an example of a process900that supports BFR for a multi-TRP in a PCell/PScell, in accordance with aspects of the present disclosure. In some examples, process900may implement aspects of wireless communication systems100and/or700. Features of process900may be implemented by PCell/PScell and/or UE120. In some examples, PCell/PScell may be associated with multiple TRPs704.

PCell/PScell may configure UE120with a carrier that is configured with, or otherwise associated with, a first CORESET pool index value (e.g., CORESETPoolIndex=0) and a second CORESET pool index value (e.g., CORESETPoolIndex=1). PCell/PScell may also configure UE120with the set of candidate beams available for a BFR procedure, the set of candidate beams including a first subset of candidate beams associated with the first CORESET pool index value and a second subset of candidate beams associated with the second CORESET pool index value.

At902, PCell/PsCell may transmit (and UE120may receive), a configuration for BFD reference signals (e.g., BFD RS(s)). That is, BFD may be based on periodic control state information-reference signal (CSI-RS) resources configured by radio resource control (RRC) (e.g., RRC parameter failureDetectionResources). Up to two single port reference signals may be configured. If not configured, the reference signal sets indicated by the active TCI states of CORESETs monitored by UE120may be used. For an active TCI state of a CORESET, there may be two reference signal indices (e.g., with which QCL Type-D may be used).

At904, UE120may determine or otherwise declare a beam failure on an active beam of PCell/PScell associated with the first CORESET pool index value or the second CORESET pool index value. In some examples, the physical layer of UE120may assess the radio link quality according to the BFD set against a threshold (e.g., Qout). If the radio link quality is worse than Qout for all of the reference signals in the BFD resource set, the physical layer may provide an indication to higher layers (e.g., an indication that a beam failure has been detected).

At906, UE120may select a new candidate beam based on monitoring a resource associated with the first CORESET pool index value or the second CORESET pool index value, e.g., perform CBD. In some examples, CBD may be based on periodic CSI-RS/SSB configured by RRC (e.g., RRC parameter candidateBeamRSList). In some examples, up to 16 resources may be configured with the corresponding random access preamble index (e.g., for RACH). Upon request from higher layers, UE120may provide a reference signal index and RSRP among the lists that have equal or larger RSRP values than a configurable threshold (e.g., Qin). For example, Qin may be defined as a level where a downlink radio link can be received meaningfully and reliably, and may correspond to a particular BLER (e.g., 2%) of a downlink transmission. UE120may initiate RACH procedures (e.g., contention-free RACH procedures) based on the random access resource (e.g., random access preamble index) associated with a selected reference signal index with an RSRP value above the threshold (e.g., RS index Qnew). Accordingly, and at908, UE120may transmit (and PCell/PScell may receive) a RACH message, e.g., the access message.

At910, PCell/PScell may transmit (and UE120may receive) a BFR response. For example, UE120may monitor PDCCH in a search space set, such as provided by a parameter (e.g., recoverySearchSpaceID), for detection of a DCI format, for example that is cyclic redundancy check (CRC) scramble by C-RNTI or MCS-C-RNTI starting from slot n+4. This may correspond to a random access response (e.g., BFR response in this case). If UE120receives the PDCCH within a window, the BFR procedure may be considered complete. In some aspects, the CORESET associated with the secondary synchronization signal (SSS) provided by recoverySearchSpaceID may not be used for any other SSS.

Typically, various QCL assumptions may be adopted after RACH. For PDCCH monitoring and a SSS provided by recoverySearchSpaceID and for corresponding PDSCH receptions, UE120may assume the same QCL parameters as the ones associated with the R index Qnew (e.g., the QCL parameters of the new candidate beam) until UE120receives, e.g., by higher layers, an activation for a TCI state or any of the parameters TCI-StatesPDCCH-ToAddList and/or TCI-StatesPDCCH-ToReleaseList. After, for example the 28th, symbol from a last symbol of a first PDCCH reception and a SSS provided by recoverySearchSpaceID where UE120detects a DCI format with CRC scramble by C-RNTI or MCS-C-RNTI, UE120may assume the same QCL parameters as the ones associated with the reference signal index Qnew for PDCCH monitoring in a CORESET with pool index value 0.

However, according to aspects of the described techniques UE120may monitor for an access response message (e.g., the BFR response) on a first recovery search configured with a first CORESET that is associated with the first CORESET pool index value or on a second recovery search space configured with a second CORESET that is associated with the second CORESET pool index value. That is, two different CORESETS may be associated with two different recovery search spaces (e.g., two recoverySearchSpaceIDs can be configured). The two CORESETs may be configured with different CORESET pool index values. A recoverySearchSpaceID may be associated with a CORESET pool index value through the corresponding CORESET. Accordingly, UE120may determine that the new candidate beam is associated with the first subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the first recovery search space. Similarly, UE120may determine that the new candidate beam is associated with the second subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the second recovery search space. UE120may receive a control channel signal (e.g., PDCCH, which may include the access response message, or BFR response in this example) and the corresponding recovery search space and determine that the BFR procedure is complete based on receiving the control channel signal in the corresponding recovery search space.

In some aspects, only one CORESET may be used for BFR purposes. For example, UE120may monitor for the access response message (e.g., the BFR response) on a first recovery search associated with the first CORESET pool index value or on a second recovery search space associated with the second CORESET pool index value. In this example, the first and second recovery search spaces may be associated with a common CORESET (e.g., the single CORESET used for BFR purposes). In one example, this may include two recoverySearchSpaceIDs being configured, both associated with the same CORESET. The first recovery search space (e.g., the first recoverySearchSpaceId) may be associated with the first CORESET pool index value (e.g., CORESETPoolIndex=0) and the second recovery search space (e.g., the second recoverySearchSpaceID) may be associated with the second CORESET pool index value (e.g., CORESETPoolIndex=1). This association between the second recovery search space and the second CORESET pool index value may be a direct association (e.g., not through the CORESET).

If the RACH message transmitted at908in slot n is associated with a new candidate beam (e.g., Qnew) that is associated with the value of CORESET pool index, UE120may monitor PDCCH in a search space set, such as provided by recoverySearchSpaceID that is associated with the same value of CORESET pool index, such as for detection of a DCI format with CRC scrambled by C-RNTI or MCS-C-RNTI starting from, for example, slot n+4. The BFR procedure for a CORESET pool index value may be completed at910when UE120receives PDCCH (e.g., the BFR response) in the corresponding recovery search space. PDCCH and corresponding PDSCH reception may use the same beam as Qnew uses (e.g., the new candidate beam).

Accordingly, UE120may determine that the new candidate beam is associated with the first subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the first recovery search space. Similarly, UE120may determine that the new candidate beam is associated with the second subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the second recovery search space. UE120may receive a control channel signal (e.g., PDCCH, which may be an example of the access response message, or BFR response in this example) in the corresponding recovery search space and determine that the BFR procedure is complete, at912, based on receiving the control channel signal in the corresponding recovery search space.

FIG.10illustrates example operations1000that supports BFR for a multi-TRP in a PCell, in accordance with aspects of the present disclosure. In some examples, operations1000may implement aspects of wireless communication systems100and/or700, and/or process900. Aspects of operations1000may be implemented by PCell1001a, UE120, and/or SCell1001b, which may be examples of corresponding devices described herein. In some aspects, PCell and/or SCell may each be associated with multiple TRPs704, respectively. Operations1000illustrates an example of an SCell BFR procedure that may be modified, at least in some aspects, according to the described techniques when a carrier on PCell experiences beam failure.

PCell may configure UE120with a carrier that is configured with, or otherwise associated with, a first CORESET pool index value (e.g., CORESETPoolIndex=0) and a second CORESET pool index value (e.g., CORESETPoolIndex=1). PCell may also configure UE120with the set of candidate beams available for a BFR procedure, the set of candidate beams including a first subset of candidate beams associated with the first CORESET pool index value and a second subset of candidate beams associated with the second CORESET pool index value.

As mentioned above, aspects of the described techniques may involve using a SCell BFR procedure when the beam failure on the active beam of PCell is associated with the second CORESET pool index value (e.g., CORESETPoolIndex=1). Operations1000illustrates one non-limiting example of such a BFR procedure.

At1002, SCell may transmit (and UE120may receive) a configuration for BFD reference signals. That is, BFD may be based on periodic CSI-RS resources configured by RRC (e.g., RRC parameter failureDetectionResources). At1004, UE120may determine or otherwise detect a beam failure on an active beam of SCell associated with the first CORESET pool index value or the second CORESET pool index value.

At1006, UE120may declare a beam failure and initiate BFR. Although operations1000illustrates beam failure based on the reference signals and BFD based on SCell b, aspects of the described techniques may use the same process for BFD on PCell1001a. That is, although operations1000illustrates UE120detecting or otherwise declaring BFD on SCell1001b, it is to be understood that, in accordance with the described techniques, UE120may similarly detect or otherwise declare BFD on a carrier of PCell a.

At1008, UE120may transmit (and PCell may receive) a LRR message. The LRR message may be transmitted on PCell (e.g., PUCCH-PCell and/or PUCCH-SCell) in which the PUCCH BFR is configured. The LRR message may be similar to a scheduling request (SR) and use PUCCH format 0 or 1. The LRR message may be transmitted in an uplink control channel.

At1010, PCell may transmit (and UE120may receive) a normal uplink (UL) grant. The UL grant may include or use C-RNTI/MCS-C-RNTI and may serve as a response message to the LRR message. The UL grant may schedule a physical uplink shared channel (PUSCH) for UE120in which a BFR MAC CE may be transmitted. If UE120already has an UL grant configured, the LRR message transmitted at1008and the UL grant transmitted at1010may be skipped.

At1012, UE120may perform CBD. That is, before sending the BFR response indicating the MAC CE, UE120may identify a suitable (e.g., the best) new beam (e.g., select a new candidate beam) for the failed SCell (or PCell in this example). CBD may be similar to the description provided in operations1000. Up to 64 resources (e.g., candidateBeamRSSCellList, or candidateBeamRSPCellList in this example) may be configured in the set of candidate beams and they may be transmitted on the failed SCell (or PCell in this example) or on another CC in the same band. In some aspects, the BFR procedure illustrated in operations1000may not include a RACH process and, therefore, CBD resources may not be associated with a RACH resource.

At1014, UE120may transmit (and PCell may receive) a BFR MAC CE. In some aspects, the BFR MAC CE may carry or otherwise convey an indication of which cell the beam failure has occurred (e.g., a SCell index, or a PCell index in this example) and/or identify potential new candidate beams. For example, the BFR MAC CE may include a first row of Ciindications (e.g., up to eight Ciindications), with each Ciindication set to 1 to indicate that BFD has occurred in that CC. For each Ciindication set to 1, a subsequent row in the MAC CE may include an access control (AC) field set to 1 indicating that the candidate reference signal ID field is present. The remaining bits in the row may carry the candidate reference signal ID. The BFR MAC CE may be transmitted to PCell and/or SCell (e.g., may be transmitted to any cell, including the failed cell).

Accordingly, in some aspects UE120may configure the access message (e.g., BFR MAC CE) to indicate the CORESET pool index value associated with the detected beam failure. That is, the MAC CE may explicitly indicate the CORESET pool index value corresponding to the BFD.

In some examples, UE120may configure the access message (e.g., BFR MAC CE) to indicate the beam failure was detected on the PCell1001a. In this example, UE120may transmit or otherwise convey the access message using a first set of random access resources associated with the first CORESET pool index value or using a second set of random access resources associated with the second CORESET pool index value. That is, the MAC CE may only indicate the BFD for PCell1001a, and the RACH resource/random access preamble index may implicitly determine (e.g., indicate) the CORESET pool index value associated with the BFD (e.g., and the Qnew/new candidate beam for that CORESET pool index value).

At1016, PCell may transmit (and UE120may receive) a BFR response. In some aspects, the BFR response to the MAC CE may be an UL grant scheduling a new transmission (e.g., with a toggled/changed new data indicator (NDI), meaning the NDI is set to a value indicated there is new data) for the same hybrid automatic repeat request (HARQ) process as the PUSCH carrying the MAC CE. In this example, the DCI may indicate which HARQ process to be used by the UE120. Since transmissions and retransmissions are scheduled using the same framework, the UE120may need to know whether the transmission is a new transmission (e.g., in which case the UE120may flush a soft buffer to make room for the new data), or a retransmission (e.g., in which case the UE120may perform soft combining of new data with data currently in the buffer). Thus, the NDI bit may be set to indicate whether the transmission will include new data and the receive buffer should be flushed. If the new candidate beam is reported in the BFR MAC CE, such as 28 symbols from the end of the BFR response (e.g., in the PDCCH), all CORESET beams on the failed cell (e.g., SCell1001b, or PCell1001ain this example), may be reset to the new candidate beam. If the failed cell is a PUCCH-SCell, the PUCCH-spatialRelationInfo may be configured. If the LLR is not transmitted on the failed cell, PUCCH beams on the failed cell may be reset to the new candidate beam.

At1016, UE120may receive a control channel signal (e.g., PDCCH, which may be an example of the access response message, or BFR response in this example) in the corresponding recovery search space and determine that the BFR procedure is complete.

In some examples, this may include UE120monitoring for an access response message (e.g., the BFR response) on a first recovery search space configured with a first CORESET that is associated with the first CORESET pool index value or on a second recovery search space configured with a second CORESET that is associated with the second CORESET pool index value. That is, two different CORESETS may be associated with two different recovery search spaces (e.g., two recoverySearchSpaceIDs can be configured). The two CORESETs may be configured with different CORESET pool index values. A recoverySearchSpaceID may be associated with a CORESET pool index value through the corresponding CORESET. Accordingly, UE120may determine that the new candidate beam is associated with the first subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the first recovery search space. Similarly, UE120may determine that the new candidate beam is associated with the second subset of candidate beams and monitor for an access response message (e.g., the BFR response) on the second recovery search space. UE120may receive a control channel signal (e.g., the access response message, or BFR response in this example) in the corresponding recovery search space and determine that the BFR procedure is complete based on receiving the control channel signal in the corresponding recovery search space.

In some examples, only one CORESET may be used for BFR purposes. For example, UE120may monitor for the access response message (e.g., the BFR response) on a first recovery search space associated with the first CORESET pool index value or on a second recovery search space associated with the second CORESET pool index value. In this example, the first and second recovery search spaces may be associated with a common CORESET (e.g., the single CORESET used for BFR purposes). In one example, this may include two recoverySearchSpaceIDs being configured, both associated with the same CORESET. The first recovery search space (e.g., the first recoverySearchSpaceID) may be associated with the first CORESET pool index value (e.g., CORESETPoolIndex=0) and the second recovery search space (e.g., the second recoverySearchSpaceID) may be associated with the second CORESET pool index value (e.g., CORESETPoolIndex=1). This association between the second recovery search space and the second CORESET pool index value may be a direct association (e.g., not through the CORESET).

FIGS.11A and11Billustrate example MAC CE structures that may be used for BFR purposes.FIG.11A, shows an example Scell BFR MAC CE with a highest SERVCellIndex less than eight (e.g., include a first row of Ciindications up to seven Ciindications for seven Scells). A Ci indication equal to 1 indicates a beam failure detection in that CC. When Ci=1, the BFR MAC CE may convey an indication of an additional Ci field and corresponding AC/candidate reference signal ID fields associated with the CORESET pool index value 1 in the PCell. The AC field may correspond to the candidate reference signal ID field.

FIG.11Billustrates an example Scell BFR MAC CE with a field structure which includes the highest SERVCellIndex greater than 8 (21 in the example).

Example Configuration of PUCCH-BFR for TRP Specific BFR

As mentioned above, a UE may be provided with BFD resources enabling the UE to perform BFD and CBD operations. However, the introduction of a multi-TRP operation to increase system capacity as well as reliability in the wireless communication system may present certain challenges with regard to BFD and BFR procedures.

In some cases, further clarification may be desirable regarding techniques and apparatuses for per-TRP BFR, which enables separate BFD and separate CBD for the beams corresponding to a TRP in a control channel that is configured with two values of CORESET pool indices.

Potential enhancements to enable per-TRP based beam failure recovery may include TRP-specific BFD, TRP-specific new candidate beam identification, TRP-specific BFRQ, BS (e.g., gNB) response enhancement, and UE behavior clarification on QCL, spatial relation assumption, UL power control for DL and UL channels, and after receiving the response from the BS.

Aspects of the present disclosure provide enhancements to enable per beam group based (effectively per-TRP based) beam failure recovery, and more particularly, techniques for the configuration of physical uplink control channel (PUCCH) beam failure recovery (BFR) for transmission reception point (TRP) (or beam group) specific BFR. In TRP specific BFR, after UE transmits BFRQ to initiate the TRP (beam group) specific BFR, the timing (and signalling mechanism) for the gNB response for the TRP specific BFRQ should be specified. This allows the UE to know that the BFRQ transmission is successful and, hence, the UE may stop further BFRQ attempts.

Aspects of the present disclosure provide various options for the gNB response to TRP specific BFRQ, for example, depending on how the BFRQ is sent. For example, the gNB response may depend on whether the BFRQ information is sent in TRP specific BFR MAC-CE (Referred to herein as Case 1), the BFRQ is sent as the preamble in CFRA MsgA/1 (Referred to herein as Case 2), or the BFRQ is sent in UCI carried in PUCCH/PUSCH (Referred to herein as Case 3).

In one or more of these cases, after X symbols form receiving the gNB response, both gNB and UE may reset the beam(s) and/or power control parameters for certain channels/RSs, at least for those channels/RSs associated with the failed TRP, if a new candidate beam is identified for the failed TRP.

FIG.12is a flow diagram illustrating example operations1200for wireless communication, in accordance with certain aspects of the present disclosure. The operations1200may be performed, for example, by a UE (e.g., such as the UE120ain the wireless communication network100). The operations1200may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the UE in operations1200may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

The operations1200begin, at1202, by communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs.

At1204, the UE detects a beam failure in a first one of the beam groups.

At1206, the UE transmits a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected.

At1208, the UE monitoring for a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

FIG.13is a flow diagram illustrating example operations1300for wireless communication, in accordance with certain aspects of the present disclosure. The operations1300may be performed, for example, by a network entity (e.g., such as the BS110ain the wireless communication network100). The operations1300may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor240ofFIG.2). Further, the transmission and reception of signals by the BS in operations1300may be enabled, for example, by one or more antennas (e.g., antennas234ofFIG.2). In certain aspects, the transmission and/or reception of signals by the BS may be implemented via a bus interface of one or more processors (e.g., controller/processor240) obtaining and/or outputting signals.

Operations1300begin, at a first block1302, by receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected.

At a second block1304, the TRP transmits a response to the BFRQ based, at least in part, on how the BFRQ is received.

In certain aspects, based on the BFRQ being received via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the response is transmitted in a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARQ) ID as a PUSCH carrying the beam group specific BFR MAC CE.

In certain aspects, the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

In certain aspects, the response to the BFRQ is transmitted in the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

In certain aspects, based on the BFRQ being received via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE) that is not scheduled or activated by a downlink control information (DCI), the response is transmitted via: a DCI including a cell radio network temporary identifier (C-RNTI); a DCI including a modulation and coding scheme C-RNTI (MCS-C-RNTI); or a message including a contention resolution ID matching that of the UE.

In certain aspects, based on the BFRQ being received via a preamble in a contention free random access (CFRA) procedure, the response is transmitted in a downlink control information (DCI) search space configured for a beam group specific BFRQ.

In certain aspects, based on the BFRQ being received via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is transmitted via a downlink acknowledgment (ACK).

In certain aspects, the downlink ACK is transmitted via a standalone or transmission-scheduling downlink control information (DCI).

In certain aspects, the response to the BFRQ is transmitted via a downlink control information (DCI), and wherein the DCI is scrambled with a special radio network temporary identifier (RNTI).

In certain aspects, the BFRQ is a beam group specific BFRQ, and wherein the special RNTI is dedicated to the beam group specific BFRQ.

As noted above, a TRP may itself be a BS, or each TRP may be a radio head (RH) for a base station, where a BS may have multiple RHs. In some examples, the TRP response to a TRP (e.g., beam group) specific BFRQ may depend on whether the BFRQ is sent in TRP specific BFR MAC-CE (Case 1), as the preamble in CFRA MsgA/1 (Case 2), or in UCI carried in PUCCH/PUSCH (Case 3).

There are various options for the first case, when BFRQ info is sent in TRP specific BFR MAC-CE. According to a first option, the response may be sent via the next DCI scheduling a new PUSCH transmission with a same HARQ ID as the PUSCH carrying the TRP specific BFR MAC-CE.

The new PUSCH transmission may be indicated by a toggled new data indicator (NDI) field in the DCI. In some cases, the MAC-CE may be sent in MsgA/3 whose HARQ ID is 0. In some cases, this option may be restricted to a MAC-CE not sent in MsgA/3 in 2/4-step RACH (e.g., restricted to a MAC-CE sent in a PUSCH scheduled/activated by DCI).

If the MAC-CE is sent in a MsgA/3 in 2/4-step RACH procedure, the response may have various additional/alternative options. According to one such option, the response is sent via the next DCI with C-RNTI or MCS-C-RNTI after MsgA/3 (at least when the RACH is CBRA and C-RNTI MAC-CE is sent in MsgA/3). According to another such option, the response may be sent via the MsgB/4 containing a UE Contention Resolution Identity matching that of the UE (at least when the RACH is CBRA and C-RNTI MAC-CE is not sent in MsgA/3).

When the BFRQ is sent as the preamble in CFRA MsgA/1, the response may be sent via the DCI with C-RNTI or MCS-C-RNTI received in a search space configured to receive the response for the TRP specific BFRQ (e.g., a BFRQ unique to a particular TRP or a BFRQ unique to a particular beam group of the TRP). In such cases, the UE may use a same Rx beam for receiving the candidate beam associated with the RACH occasion where the preamble is sent. In some cases, the candidate beam, RACH occasion, and/or the search space for the CFRA based TRP specific BFR may be configured by RRC signaling, for example, in the same information element (IE).

When the BFRQ is sent in UCI carried in PUCCH/PUSCH, the response may be sent via a downlink acknowledgment (of the PUCCH/PUSCH) from the gNB. In some cases, this downlink acknowledgment may be carried in a DCI scheduling DL/UL transmission or in a standalone DCI (without scheduling any transmission). In either case, the DCI may carry a bitmap indicating ACK/NACK (A/N) for each of multiple packets carrying UCI, which can be transmitted sequentially in a time window. As an alternative, the downlink acknowledgment for BFRQ can be sent in a MAC-CE in PDSCH.

For any of the cases (1-3) discussed above, if the response is conveyed via a DCI, the DCI can be scrambled with a special RNTI, sent by a CORESET with special ID or group ID, and/or sent in a special search space. Such a RNTI, ID, group ID, or search space may be considered special if dedicated to reception of the response for TRP specific BFRQ. A CORESET group ID may include a CORESET pool index in case of multi-DCI (mDCI) based multi-TRP (mTRP) scenarios.

Beam resetting (and power control parameter resetting) typically occurs sometime after a gNB response is received (which indicates the BFRQ was successfully received). For example, in some cases, after X symbols from receiving the gNB response, both the gNB and UE may reset the beam(s) and/or power control parameters for certain channels/RSs (at least those channels/RSs associated with the failed TRP), if a new candidate beam is identified for the failed TRP.

The channel(s)/RS(s) may include any combinations of PDCCH, PDSCH, CSI-RS, PUCCH, PUSCH, SRS, and any combinations of various types per channel/RS listed herein.

Beam resetting for PDCCH may include CORESET(s) with different ID(s). In some cases, the beam resetting may be applied to a subset of CORESET(s) associated with the failed TRP (e.g. the CORESET with lowest ID associated with the failed TRP in the active DL BWP of the serving cell).

Beam resetting for PDSCH may include that scheduled with offset from the scheduling DCI greater or less than the beam switch latency threshold. For example, the beam resetting may be applied to the PDSCH with offset both greater and less than the threshold.

Beam resetting for SRS may include any combinations of SRS types with purposes for codebook, non-codebook, antenna switching, beam management, and/or positioning. For example, the beam resetting may be applied to only SRS for codebook and non-codebook purposes.

Beam resetting for CSI-RS may include any combination of CSI-RS types with purposes for channel state feedback (CSF), beam management (BM), tracking reference signals (TRS), or positioning. For example, the beam resetting may be applied to only the CSF and TRS.

For any such beam resetting, the beam(s) of those channel(s)/RS(s) may be reset with the following options. According to a first option, the beam(s) are reset to the new candidate beam reported in TRP specific BFR MAC-CE if exists. According to a second option, the beam(s) are reset to the new candidate beam selected by UE to transmit the preamble in RACH based TRP specific BFR.

In some cases, the reset power control parameters associated with reset beam(s) for UL channel(s)/RS(s) may include P0, alpha, close-loop index, and pathloss RS.

In some cases, the gNB and/or UE can know (identify) the failed TRP ID (beam group ID) with the following options. According to a first option, a failed TRP ID is explicitly reported in MAC-CE/UCI. According to a second option, a failed TRP ID is implied by selected candidate beam, RACH occasion, search space for receiving BFRQ response, which can be configured/indicated per TRP.

In some cases, the failed TRP ID associated with the channel(s)/RS(s) to which beam resetting will be applied can be identified via various options, for a TRP ID associated with a CORESET, for mDCI mTRP (indicated by CORESET Pool index per CORESET) or for sDCI mTRP. According to a first option, the failed TRP ID is indicated by a new TRP ID per CORESET, or implied by CORESET ID if its ID space is split among TRPs. According to a second option, the failed TRP ID is indicated by the TRP ID associated with the TCI state assigned to the CORESET. In some cases, TRP ID per TCI state may be indicated by a new TRP ID per TCI state, or implied by TCI state ID if its ID space is split among TRPs.

There are also various options for TRP ID associated with other type of channel/RS. According to a first option, the TRP ID can be configured in the channel/RS resource configuration. According to a second option, the TRP ID is indicated by the DCI scheduling/activating the transmission of the channel/RS. According to a third option, the TRP ID is implied by the TRP ID associated with the CORESET carrying the DCI scheduling/activating the transmission of the channel/RS.

In some cases, the new candidate beam resetting certain channel(s)/RS(s) at least for a failed TRP in the active BWP of a CC can be applied to the active BWP or all BWPs of multiple CCs.

If the new candidate beam is applied to a particular type of channel/RS for a failed TRP ID in the active BWP of a CC, it may also be applied to the same type of channel/RS for the same TRP ID to the active BWP or all BWPs of multiple CCs. For example, if the new candidate beam is applied to all CORESETs & PUCCH resources associated with TRP 1 in the active BWP in CC 1, it is also applied to all CORESETs & PUCCHs associated with TRP 1 in all BWPs of every CC in a CC list.

If the new candidate beam is applied to a particular resource ID of channel/RS for a failed TRP ID in the active BWP of a CC, it may also be applied to the same resource ID of channel/RS for the same TRP ID to the active BWP or all BWPs of multiple CCs. For example, if the new candidate beam is applied to CORESET with ID 0 or lowest ID associated with TRP 1 in the active BWP of CC 1, it is also applied to CORESET with ID 0 or lowest ID associated with TRP 1 in all BWPs of every CC in a CC list.

In some cases, the gNB may configure multiple CC lists for DL and UL beam resetting, respectively. In case of multiple CC lists in DL and/or in UL, the DL/UL CC list containing the CC with the failed TRP may be used to perform cross-CC DL/UL beam resetting.

FIG.14illustrates a communications device1400that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG.12. The communications device1400includes a processing system1402coupled to a transceiver1408(e.g., a transmitter and/or a receiver). The transceiver1408is configured to transmit and receive signals for the communications device1400via an antenna1410, such as the various signals as described herein. The processing system1402may be configured to perform processing functions for the communications device1400, including processing signals received and/or to be transmitted by the communications device1400.

The processing system1402includes a processor1404coupled to a computer-readable medium/memory1412via a bus1406. In certain aspects, the computer-readable medium/memory1412is configured to store instructions (e.g., computer-executable code) that when executed by the processor1404, cause the processor1404to perform the operations illustrated inFIG.12, or other operations for performing the various techniques discussed herein for configuration of PUCCH BFR for TRP specific BFR. In certain aspects, computer-readable medium/memory1412stores code1414for communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs; code1416for detecting a beam failure in a first one of the beam groups; code1418for transmitting a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and code1420for monitoring for a response to the BFRQ based, at least in part, on how the BFRQ is transmitted. In certain aspects, the processor1404has circuitry configured to implement the code stored in the computer-readable medium/memory1412. The processor1404includes circuitry1424for communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs; circuitry1426for detecting a beam failure in a first one of the beam groups; circuity1428for transmitting a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and circuitry1430for monitoring for a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

In certain aspects, means for transmitting (e.g., means for communicating or means for outputting for transmission) may include a transmitter unit254and/or antenna(s)252of the UE120aillustrated inFIG.2and/or circuitry1424for communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs, and circuitry1428for transmitting a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected.

Means for receiving (e.g., means for communicating or means for obtaining) may include a receiver and/or antenna(s)252of the UE120aillustrated inFIG.2and/or circuitry1424for communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs. Means for communicating may include a transmitter, a receiver or both. In one example, means for detecting may include and/or circuitry1426for detecting a beam failure in a first one of the beam groups.

Means for generating, means for performing, means for determining, means for detecting, means for taking action, means for coordinating may include a processing system, which may include one or more processors, such as the receive processor258, the transmit processor264, the TX MIMO processor266, and/or the controller/processor280of the UE120aillustrated inFIG.2and/or the processing system1402of the communication device1400inFIG.14.

FIG.15illustrates a communications device1500that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG.13. The communications device1500includes a processing system1502coupled to a transceiver1508(e.g., a transmitter and/or a receiver). The transceiver1508is configured to transmit and receive signals for the communications device1500via an antenna1510, such as the various signals as described herein. The processing system1502may be configured to perform processing functions for the communications device1500, including processing signals received and/or to be transmitted by the communications device1500.

The processing system1502includes a processor1504coupled to a computer-readable medium/memory1512via a bus1506. In certain aspects, the computer-readable medium/memory1512is configured to store instructions (e.g., computer-executable code) that when executed by the processor1504, cause the processor1504to perform the operations illustrated inFIG.13, or other operations for performing the various techniques discussed herein for configuration of PUCCH BFR for TRP specific BFR. In certain aspects, computer-readable medium/memory1512stores code1514for receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and code1516for transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received. In certain aspects, the processor1504has circuitry configured to implement the code stored in the computer-readable medium/memory1512. The processor1504includes circuitry1524for receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and circuitry1526for transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received.

In certain aspects, means for transmitting (e.g., means for communicating or means for outputting for transmission) may include a transmitter and/or an antenna(s)234or the BS110aillustrated inFIG.2and/or circuitry1526for transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received. Means for receiving (or means for obtaining) may include a receiver and/or an antenna(s)234of the BS110aillustrated inFIG.2and/or circuitry1524for receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected. Means for communicating may include a transmitter, a receiver or both.

Means for generating, means for performing, means for determining, means for taking action, means for coordinating may include a processing system, which may include one or more processors, such as the transmit processor220, the TX MIMO processor230, the receive processor238, and/or the controller/processor240of the BS110aillustrated inFIG.2and/or the processing system1502of the communication device1500inFIG.15.

FIG.16is a flow diagram illustrating example operations1600for wireless communication, in accordance with certain aspects of the present disclosure. The operations1600may be performed, for example, by a UE (e.g., such as the UE120ain the wireless communication network100). The operations1600may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the UE in operations1600may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

The operations1600begin, at a first block1602, communicating using beams associated with at least two beam groups.

The operations1600may proceed, at a second block1604, by transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group.

The operations1600may proceed, at a third block1606, by receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

In certain aspects, based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the response is received via a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARM) identification (ID) as a PUSCH carrying the group specific BFR MAC CE.

In certain aspects, the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

In certain aspects, the response to the BFRQ is received via the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

In certain aspects, based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE) that is not scheduled or activated by a downlink control information (DCI), the response is received via: a DCI including a cell radio network temporary identifier (C-RNTI); a DCI including a modulation and coding scheme C-RNTI (MCS-C-RNTI); or a message including a contention resolution ID matching that of the UE.

In certain aspects, based on the BFRQ being transmitted via a preamble in a contention free random access (CFRA) procedure, the response is received via a downlink control information (DCI) in a search space configured for a beam group specific BFRQ.

In certain aspects, based on the BFRQ being transmitted via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is received via a downlink acknowledgment (ACK).

In certain aspects, the downlink ACK is received via a standalone or transmission-scheduling downlink control information (DCI).

In certain aspects, the response is received via a downlink control information (DCI), and wherein the DCI is scrambled with a special radio network temporary identifier (RNTI).

In certain aspects, the BFRQ is a beam group specific BFRQ, and wherein the special RNTI is dedicated to the beam group specific BFRQ.

In certain aspects, communicating using beams associated with at least two beam groups further comprises communicating with at least two transmission reception points (TRPs), wherein each of the at least two beam groups are associated with a different one of the at least two TRPs.

FIG.17illustrates a communications device1700that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG.16. The communications device1700includes a processing system1702coupled to a transceiver1708(e.g., a transmitter and/or a receiver). The transceiver1708is configured to transmit and receive signals for the communications device1700via an antenna1710, such as the various signals as described herein. The processing system1702may be configured to perform processing functions for the communications device1700, including processing signals received and/or to be transmitted by the communications device1700.

The processing system1702includes a processor1704coupled to a computer-readable medium/memory1712via a bus1706. In certain aspects, the computer-readable medium/memory1712is configured to store instructions (e.g., computer-executable code) that when executed by the processor1704, cause the processor1704to perform the operations illustrated inFIG.16, or other operations for performing the various techniques discussed herein for configuration of PUCCH BFR for TRP specific BFR.

In certain aspects, computer-readable medium/memory1712stores code1714for communicating using beams associated with at least two beam groups. The computer-readable medium/memory1712also stores code1716for transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. The computer-readable medium/memory1712also stores code1718for sending a response to the BFRQ based, at least in part, on how the BFRQ is received.

In certain aspects, the processor1704has circuitry configured to implement the code stored in the computer-readable medium/memory1712. The processor1704includes circuitry1724for communicating using beams associated with at least two beam groups. The processor1704also includes circuitry1726for transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. The processor1704includes circuitry1728for receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

In certain aspects, means for transmitting (e.g., means for communicating or means for outputting for transmission) may include a transmitter unit254and/or antenna(s)252of the UE120aillustrated inFIG.2and/or circuitry1724for communicating using beams associated with at least two beam groups, and circuitry1726for transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group.

Means for receiving (e.g., means for communicating or means for obtaining) may include a receiver and/or antenna(s)252of the UE120aillustrated inFIG.2and/or circuitry1724for communicating using beams associated with at least two beam groups, and circuitry1726for transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group. Means for communicating may include a transmitter, a receiver or both.

Means for generating, means for performing, means for determining, means for taking action, means for coordinating may include a processing system, which may include one or more processors, such as the receive processor258, the transmit processor264, the TX MIMO processor266, and/or the controller/processor280of the UE120aillustrated inFIG.2.

Example Aspects

1. A method of wireless communication by a user equipment (UE), comprising: communicating using beams associated with at least two beam groups; transmitting a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group; and receiving a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

2. The method of aspect 1, wherein based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the response is received via a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARQ) identification (ID) as a PUSCH carrying the group specific BFR MAC CE.

3. The method of any of aspects 1 and 2, wherein the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

4. The method of any of aspects 1-3, wherein the response to the BFRQ is received via the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

5. The method of any of aspects 1-4, wherein based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE) that is not scheduled or activated by a downlink control information (DCI), the response is received via: a DCI including a cell radio network temporary identifier (C-RNTI); a DCI including a modulation and coding scheme C-RNTI (MCS-C-RNTI); or a message including a contention resolution ID matching that of the UE.

6. The method of any of aspects 1-5, wherein based on the BFRQ being transmitted via a preamble in a contention free random access (CFRA) procedure, the response is received via a downlink control information (DCI) in a search space configured for a beam group specific BFRQ.

7. The method of any of aspects 1-6, wherein based on the BFRQ being transmitted via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is received via a downlink acknowledgment (ACK).

8. The method of any of aspects 1-7, wherein the downlink ACK is received via a standalone or transmission-scheduling downlink control information (DCI).

9. The method of any of aspects 1-8, wherein the response is received via a downlink control information (DCI), and wherein the DCI is scrambled with a special radio network temporary identifier (RNTI).

10. The method of any of aspects 1-9, wherein the BFRQ is a beam group specific BFRQ, and wherein the special RNTI is dedicated to the beam group specific BFRQ.

11. The method of any of aspects 1-10, wherein communicating using beams associated with at least two beam groups further comprises communicating with at least two transmission reception points (TRPs), wherein each of the at least two beam groups is associated with a different one of the at least two TRPs.

12. A method of wireless communication by a transmission reception point (TRP), comprising: receiving, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and transmitting a response to the BFRQ based, at least in part, on how the BFRQ is received.

13. The method of aspect 12, wherein based on the BFRQ being received via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the response is transmitted in a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARD) ID as a PUSCH carrying the beam group specific BFR MAC CE.

14. The method of any of aspects 12 and 13, wherein the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

15. The method of any of aspects 12-14, wherein the response to the BFRQ is transmitted in the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

16. The method of any of aspects 12-15, wherein based on the BFRQ being received via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE) that is not scheduled or activated by a downlink control information (DCI), the response is transmitted via: a DCI including a cell radio network temporary identifier (C-RNTI); a DCI including a modulation and coding scheme C-RNTI (MCS-C-RNTI); or a message including a contention resolution ID matching that of the UE.

17. The method of any of aspects 12-16, wherein based on the BFRQ being received via a preamble in a contention free random access (CFRA) procedure, the response is transmitted in a downlink control information (DCI) search space configured for a beam group specific BFRQ.

18. The method of any of aspects 12-17, wherein based on the BFRQ being received via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is transmitted via a downlink acknowledgment (ACK).

19. The method of any of aspects 12-18, wherein the downlink ACK is transmitted via a standalone or transmission-scheduling downlink control information (DCI).

20. The method of any of aspects 12-19, wherein the response to the BFRQ is transmitted via a downlink control information (DCI), and wherein the DCI is scrambled with a special radio network temporary identifier (RNTI).

21. The method of any of aspects 12-20, wherein the BFRQ is a beam group specific BFRQ, and wherein the special RNTI is dedicated to the beam group specific BFRQ.

22. A user equipment (UE) configured for wireless communication, comprising: a memory; and a processor coupled to the memory, the processor and the memory configured to: communicate using beams associated with at least two beam groups; transmit a beam failure recovery request (BFRQ) specific to a first beam group of the at least two beam groups based on a detected beam failure in the first beam group; and receive a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

23. The UE of aspect 22, wherein based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the processor and the memory are further configured to receive the response via a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARQ) identification (ID) as a PUSCH carrying the group specific BFR MAC CE.

24. The UE of any of aspects 22 and 23, wherein the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

25. The UE of any of aspects 22-24, wherein the processor and the memory are further configured to receive the response to the BFRQ via the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

26. The UE of any of aspects 22-25, wherein based on the BFRQ being transmitted via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE) that is not scheduled or activated by a downlink control information (DCI), the processor and the memory are further configured to receive the response via: a DCI including a cell radio network temporary identifier (C-RNTI); a DCI including a modulation and coding scheme C-RNTI (MCS-C-RNTI); or a message including a contention resolution ID matching that of the UE.

27. A transmission reception point (TRP) for wireless communication, comprising: a memory; and a processor coupled to the memory, the processor and the memory configured to: receive, from a user equipment (UE), a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and transmit a response to the BFRQ based, at least in part, on how the BFRQ is received.

28. The TRP of aspect 27, wherein based on the BFRQ being received via a beam group specific beam failure recovery (BFR) medium access control (MAC) control element (CE), the processor and the memory are further configured to transmit the response in a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARM) ID as a PUSCH carrying the beam group specific BFR MAC CE.

29. The TRP of any of aspects 27 and 28, wherein the new PUSCH is indicated via a new data indicator (NDI) in the DCI.

30. The TRP of any of aspects 27-29, wherein the processor and the memory are further configured to transmit the response to the BFRQ in the DCI scheduling the new PUSCH based on the BFRQ being transmitted via the beam group specific BFR MAC CE in a previous PUSCH scheduled or activated by a previous DCI.

31. An apparatus comprising means for performing the method of any of aspects 1 through 11.

32. An apparatus comprising means for performing the method of any of aspects 12 through 21.

33. A computer readable medium storing computer executable code thereon for wireless communications that, when executed by at least one processor, cause an apparatus to perform the method of any of aspects 1 through 11.

34. A computer readable medium storing computer executable code thereon for wireless communications that, when executed by at least one processor, cause an apparatus to perform the method of any of aspects 12 through 21.

35. A method of wireless communication by a user equipment (UE), comprising: communicating with at least two transmission reception points (TRPs) using beams associated with at least two beam groups, each associate with one of the TRPs; detecting a beam failure in a first one of the beam groups; transmitting a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and monitoring for a response to the BFRQ based, at least in part, on how the BFRQ is transmitted.

36. The method of aspect 35, wherein, if the BFRQ is sent via a beam group specific BFR medium access control (MAC) control element (CE), the response is sent in a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARM) ID as a PUSCH carrying the group specific BFR MAC CE.

37. The method of any of aspects 35 and 36, wherein the new PUSCH is indicated via a toggled new data indicator (NDI) in the DCI.

38. The method of any of aspects 35-37, wherein the response is sent in a DCI scheduling the new PUSCH only if the BFRQ is sent via a beam group specific BFR MAC CE in a PUSCH scheduled or activated by a DCI.

39. The method of any of aspects 35-38, wherein, if the BFRQ is sent via a beam group specific BFR medium access control (MAC) control element (CE) conveyed in a message that is not scheduled or activated by a downlink control information (DCI), the response is sent in a DCI after the message with a C-RNTI or MCS-C-RNTI.

40. The method of any of aspects 35-39, wherein, if the BFRQ is sent via a beam group specific BFR medium access control (MAC) control element (CE) conveyed in a message that is not scheduled or activated by a downlink control information (DCI), the response is sent in a message containing a contention resolution ID matching that of the UE.

41. The method of any of aspects 35-40, wherein, if the BFRQ is sent via a preamble in a contention free random access (CFRA) procedure, the response is sent in a downlink control information (DCI) received in a search space configured to receive the response for a beam group specific BFRQ.

42. The method of any of aspects 35-41, wherein the UE uses a same receive beam for receiving a candidate beam associated with a RACH occasion in which the preamble is sent.

43. The method of any of aspects 35-42, further comprising receiving radio resource control (RRC) signaling configuring at least one of the candidate beam, RACH occasion, or search space for the CFRA based beam group specific BFR.

44. The method of any of aspects 35-43, wherein, if the BFRQ is sent via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is conveyed via a downlink acknowledgment.

45. The method of any of aspects 35-44, wherein the downlink acknowledgment is conveyed via a standalone or transmission-scheduling downlink control information (DCI).

46. The method of any of aspects 35-45, wherein the DCI carries a bitmap indicating acknowledgment feedback for each of multiple packets carrying UCI.

47. The method of any of aspects 35-46, wherein the downlink acknowledgment is conveyed via a medium access control (MAC) control element (CE) in a physical downlink shared channel (PDSCH).

48. The method of any of aspects 35-47, wherein the DCI is scrambled with a special radio network temporary identifier (RNTI) dedicated for reception of a response for the beam group specific BFRQ.

49. The method of any of aspects 35-48, wherein the DCI is sent at least one of: by a control resource set (CORESET) with a special ID or group ID; or in a special search space.

50. The method of any of aspects 35-49, further comprising determining when to perform a beam reset after receiving the response to the BFRQ.

51. The method of any of aspects 35-50, wherein the UE performs the beam reset a number of symbols after receiving the response to the BFRQ for one or more channels or reference signals (RSs) associated with the beam group in which the beam failure was detected, if a new candidate beam is identified for that beam group.

52. The method of any of aspects 35-51, wherein the beam reset is applied to a subset of control resource sets (CORESETs) associated with the beam group in which the beam failure was detected.

53. The method of any of aspects 35-52, wherein beams for the one or more channels or RSs are reset to: the new candidate beam, if identified for the beam group in which the beam failure was detected; or a new candidate beam selected by the UE to transmit a preamble in a random access channel (RACH) based beam group specific BFR.

54. The method of any of aspects 35-53, further comprising resetting power control parameters associated with one or more reset beams for uplink transmissions.

55. The method of any of aspects 35-54, further comprising identifying an ID associated with the beam group in which the beam failure was detected.

56. The method of any of aspects 35-55, wherein the ID is: explicitly identified via at least one of a medium access control (MAC) control element (CE) or uplink control information (UCI); implicitly by selection of a candidate beam, RACH occasion, or search space for receiving the BFRQ response; or via association with a control resource set (CORESET).

57. The method of any of aspects 35-56, wherein the UE applies the beam reset to one or more active bandwidth parts (BWPs) of one or more component carriers (CCs).

58. The method of any of aspects 35-57, wherein the UE applies the beam reset to certain types of channels, certain types or reference signals, or certain resource IDs.

59. A method of wireless communication by a user equipment (UE), comprising: receiving, from a user equipment, a beam failure recovery request (BFRQ) specific to a beam group in which the beam failure was detected; and sending a response to the BFRQ based, at least in part, on how the BFRQ is received.

60. The method of aspect 59, wherein, if the BFRQ is received via a beam group specific BFR medium access control (MAC) control element (CE), the response is sent in a downlink control information (DCI) scheduling a new physical uplink shared channel (PUSCH) with a same hybrid automatic repeat request (HARM) ID as a PUSCH carrying the group specific BFR MAC CE.

61. The method of any of aspects 59 and 60, wherein the new PUSCH is indicated via a toggled new data indicator (NDI) in the DCI.

62. The method of any of aspects 59-61, wherein the response is sent in a DCI scheduling the new PUSCH only if the BFRQ is sent via a beam group specific BFR MAC CE in a PUSCH scheduled or activated by a DCI.

63. The method of any of aspects 59-62, wherein, if the BFRQ is sent via a beam group specific BFR medium access control (MAC) control element (CE) conveyed in a message that is not scheduled or activated by a downlink control information (DCI), the response is sent in a DCI after the message with a C-RNTI or MCS-C-RNTI.

64. The method of any of aspects 59-63, wherein, if the BFRQ is sent via a beam group specific BFR medium access control (MAC) control element (CE) conveyed in a message that is not scheduled or activated by a downlink control information (DCI), the response is sent in a message containing a contention resolution ID matching that of the UE.

65. The method of any of aspects 59-64, wherein, if the BFRQ is received via a preamble in a contention free random access (CFRA) procedure, the response is sent in a downlink control information (DCI) received in a search space configured to receive the response for a beam group specific BFRQ.

66. The method of any of aspects 59-65, wherein the UE uses a same receive beam for receiving a candidate beam associated with a RACH occasion in which the preamble is sent.

67. The method of any of aspects 59-66, further comprising sending the UE radio resource control (RRC) signaling configuring at least one of the candidate beam, RACH occasion, or search space for the CFRA based beam group specific BFR.

68. The method of any of aspects 59-67, wherein, if the BFRQ is received via uplink control information (UCI) carried in a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH), the response is conveyed via a downlink acknowledgment.

69. The method of any of aspects 59-68, wherein the downlink acknowledgment is conveyed via a standalone or transmission-scheduling downlink control information (DCI).

70. The method of any of aspects 59-69, wherein the DCI carries a bitmap indicating acknowledgment feedback for each of multiple packets carrying UCI.

71. The method of any of aspects 59-70, wherein the downlink acknowledgment is conveyed via a medium access control (MAC) control element (CE) in a physical downlink shared channel (PDSCH).

72. The method of any of aspects 59-71, wherein the DCI is scrambled with a special radio network temporary identifier (RNTI) dedicated for reception of a response for the beam group specific BFRQ.

73. The method of any of aspects 59-72, wherein the DCI is sent at least one of: by a control resource set (CORESET) with a special ID or group ID; or in a special search space.

74. The method of any of aspects 59-73, further comprising determining when to perform a beam reset after sending the response to the BFRQ.

75. The method of any of aspects 59-74, wherein the network entity performs the beam reset a number of symbols after sending the response to the BFRQ for one or more channels or reference signals (RSs) associated with the beam group in which the beam failure was detected, if a new candidate beam is identified for that beam group.

76. The method of any of aspects 59-75, wherein the beam reset is applied to a subset of control resource sets (CORESETs) associated with the beam group in which the beam failure was detected.

77. The method of any of aspects 59-76, wherein beams for the one or more channels or RSs are reset to: the new candidate beam, if identified for the beam group in which the beam failure was detected; or a new candidate beam selected by the UE to transmit a preamble in a random access channel (RACH) based beam group specific BFR.

78. The method of any of aspects 59-77, further comprising identifying an ID associated with the beam group in which the beam failure was detected.

79. The method of any of aspects 59-78, wherein the ID is: explicitly identified via at least one of a medium access control (MAC) control element (CE) or uplink control information (UCI); implicitly by selection of a candidate beam, RACH occasion, or search space for receiving the BFRQ response; or via association with a control resource set (CORESET).

80. The method of any of aspects 59-79, wherein the network entity applies the beam reset to one or more active bandwidth parts (BWPs) of one or more component carriers (CCs).

81. The method of any of aspects 59-80, wherein the network entity applies the beam reset to certain types of channels, certain types or reference signals, or certain resource IDs.

82. An apparatus comprising means for performing the method of any of aspects 35 through 58.

83. An apparatus comprising means for performing the method of any of aspects 59 through 81.

84. An apparatus comprising at least one processor and a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to perform the method of any of aspects 35 through 58.

85. An apparatus comprising at least one processor and a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to perform the method of any of aspects 59 through 81.

86. A computer readable medium storing computer executable code thereon for wireless communications that, when executed by at least one processor, cause an apparatus to perform the method of any of aspects 35 through 58.

87. A computer readable medium storing computer executable code thereon for wireless communications that, when executed by at least one processor, cause an apparatus to perform the method of any of aspects 59 through 81.

Additional Considerations