Patent ID: 12199729

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

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

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

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

FIG.1is a diagram illustrating an example of a wireless communications system and an access network100. The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations102, UEs104, an Evolved Packet Core (EPC)160, and another core network190(e.g., a 5G Core (5GC)). The base stations102may include macrocells (high power cellular base station) and/or small cells (low power cellular base station). The macrocells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations102configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC160through first backhaul links132(e.g., S1 interface). The base stations102configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network190through second backhaul links184. In addition to other functions, the base stations102may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations102may communicate directly or indirectly (e.g., through the EPC160or core network190) with each other over third backhaul links134(e.g., X2 interface). The first backhaul links132, the second backhaul links184, and the third backhaul links134may be wired or wireless.

The base stations102may wirelessly communicate with the UEs104. Each of the base stations102may provide communication coverage for a respective geographic coverage area110. There may be overlapping geographic coverage areas110. For example, the small cell102′ may have a coverage area110′ that overlaps the coverage area110of one or more macro base stations102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links120between the base stations102and the UEs104may include uplink (UL) (also referred to as reverse link) transmissions from a UE104to a base station102and/or downlink (DL) (also referred to as forward link) transmissions from a base station102to a UE104. The communication links120may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations102/UEs104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).

Certain UEs104may communicate with each other using device-to-device (D2D) communication link158. The D2D communication link158may use the DL/UL WWAN spectrum. The D2D communication link158may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP)150in communication with Wi-Fi stations (STAs)152via communication links154in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs152/AP150may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP150. The small cell102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station102, whether a small cell102′ or a large cell (e.g., macro base station), may include and/or be referred to as an eNB, gNodeB (gNB), or another type of base station. Some base stations, such as gNB180may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE104. When the gNB180operates in mmW or near mmW frequencies, the gNB180may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Frequency range bands include frequency range 1 (FR1), which includes frequency bands below 7.225 GHz, and frequency range 2 (FR2), which includes frequency bands above 24.250 GHz. Communications using the mmW/near mmW radio frequency (RF) band (e.g., 3 GHz-300 GHz) has extremely high path loss and a short range. Base stations/UEs may operate within one or more frequency range bands. The mmW base station180may utilize beamforming182with the UE104to compensate for the extremely high path loss and short range. The base station180and the UE104may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

The base station180may transmit a beamformed signal to the UE104in one or more transmit directions182′. The UE104may receive the beamformed signal from the base station180in one or more receive directions182″. The UE104may also transmit a beamformed signal to the base station180in one or more transmit directions. The base station180may receive the beamformed signal from the UE104in one or more receive directions. The base station180/UE104may perform beam training to determine the best receive and transmit directions for each of the base station180/UE104. The transmit and receive directions for the base station180may or may not be the same. The transmit and receive directions for the UE104may or may not be the same.

The EPC160may include a Mobility Management Entity (MME)162, other MMEs164, a Serving Gateway166, a Multimedia Broadcast Multicast Service (MBMS) Gateway168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway172. The MME162may be in communication with a Home Subscriber Server (HSS)174. The MME162is the control node that processes the signaling between the UEs104and the EPC160. Generally, the MME162provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway166, which itself is connected to the PDN Gateway172. The PDN Gateway172provides UE IP address allocation as well as other functions. The PDN Gateway172and the BM-SC170are connected to the IP Services176. The IP Services176may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC170may provide functions for MBMS user service provisioning and delivery. The BM-SC170may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway168may be used to distribute MBMS traffic to the base stations102belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network190may include a Access and Mobility Management Function (AMF)192, other AMFs193, a Session Management Function (SMF)194, and a User Plane Function (UPF)195. The AMF192may be in communication with a Unified Data Management (UDM)196. The AMF192is the control node that processes the signaling between the UEs104and the core network190. Generally, the AMF192provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF195. The UPF195provides UE IP address allocation as well as other functions. The UPF195is connected to the IP Services197. The IP Services197may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packet Switch (PS) Streaming (PSS) Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station102provides an access point to the EPC160or core network190for a UE104. Examples of UEs104include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs104may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE104may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again toFIG.1, in certain aspects, the UE104may include a beam recovery component198which is configured to receive data from a first transmission reception point (TRP) and a second TRP in a serving cell based on a physical downlink control channel (PDCCH) of the first TRP and the second TRP, where the PDCCH of the first TRP and second TRP each received over separate beams. The beam recovery component198is also configured to detect beam failure of the PDCCH of the first TRP and to perform beam failure recovery for the first TRP by transmitting a beam failure indication indicating a new beam for the PDCCH of the first TRP.

Referring still toFIG.1, in certain aspects, the base station102/180may include a beam configuration component199which is configured to transmit data to a user equipment (UE) based on a physical downlink control channel (PDCCH) of the second TRP, where the PDCCH of the second TRP is transmitted to the UE over a separate beam than a PDCCH of the first TRP. The beam configuration component199is also configured to receive a beam failure indication from the UE in response to a beam failure of the PDCCH of the first TRP, and to configure a new beam for the PDCCH of the first TRP based on the beam failure indication.

Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

FIG.2Ais a diagram200illustrating an example of a first subframe within a 5G/NR frame structure.FIG.2Bis a diagram230illustrating an example of DL channels within a 5G/NR subframe.FIG.2Cis a diagram250illustrating an example of a second subframe within a 5G/NR frame structure.FIG.2Dis a diagram280illustrating an example of UL channels within a 5G/NR subframe. The 5G/NR frame structure may be frequency division duplexed (FDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for either DL or UL, or may be time division duplexed (TDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided byFIGS.2A,2C, the 5G/NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL), where D is DL, U is UL, and F is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL). While subframes 3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI), or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI). Note that the description infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission). The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ0 to 4 allow for 1, 2, 4, 8, and 16 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology p, there are 14 symbols/slot and 2 slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2*15 kHz, where y is the numerology 0 to 4. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrier spacing of 240 kHz. The symbol length/duration is inversely related to the subcarrier spacing.FIGS.2A-2Dprovide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 s. Within a set of frames, there may be one or more different bandwidth parts (BWPs) (see2B) that are frequency division multiplexed. Each BWP may have a particular numerology.

A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

As illustrated inFIG.2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as Rx for one particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and phase tracking RS (PT-RS).

FIG.2Billustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. A PDCCH within one BWP may be referred to as a control resource set (CORESET). Additional BWPs may be located at greater and/or lower frequencies across the channel bandwidth. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE104to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block (also referred to as SS block (SSB)). The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

As illustrated inFIG.2C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS). The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG.2Dillustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and hybrid automatic repeat request (HARQ) ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG.3is a block diagram of a base station310in communication with a UE350in an access network. In the DL, IP packets from the EPC160may be provided to a controller/processor375. The controller/processor375implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor375provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor316and the receive (RX) processor370implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor316handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator374may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE350. Each spatial stream may then be provided to a different antenna320via a separate transmitter318TX. Each transmitter318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE350, each receiver354RX receives a signal through its respective antenna352. Each receiver354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor356. The TX processor368and the RX processor356implement layer 1 functionality associated with various signal processing functions. The RX processor356may perform spatial processing on the information to recover any spatial streams destined for the UE350. If multiple spatial streams are destined for the UE350, they may be combined by the RX processor356into a single OFDM symbol stream. The RX processor356then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station310. These soft decisions may be based on channel estimates computed by the channel estimator358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station310on the physical channel. The data and control signals are then provided to the controller/processor359, which implements layer 3 and layer 2 functionality.

The controller/processor359can be associated with a memory360that stores program codes and data. The memory360may be referred to as a computer-readable medium. In the UL, the controller/processor359provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC160. The controller/processor359is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station310, the controller/processor359provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator358from a reference signal or feedback transmitted by the base station310may be used by the TX processor368to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor368may be provided to different antenna352via separate transmitters354TX. Each transmitter354TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station310in a manner similar to that described in connection with the receiver function at the UE350. Each receiver318RX receives a signal through its respective antenna320. Each receiver318RX recovers information modulated onto an RF carrier and provides the information to a RX processor370.

The controller/processor375can be associated with a memory376that stores program codes and data. The memory376may be referred to as a computer-readable medium. In the UL, the controller/processor375provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE350. IP packets from the controller/processor375may be provided to the EPC160. The controller/processor375is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor368, the RX processor356, and the controller/processor359may be configured to perform aspects in connection with198ofFIG.1.

At least one of the TX processor316, the RX processor370, and the controller/processor375may be configured to perform aspects in connection with198ofFIG.1.

Multiple transmission reception points or Tx/Rx Points (TRPs) may operate to increase capacity and reliability of wireless communication systems. A TRP is typically a set of co-located TX/RX antennas providing coverage in the same sector. The set of TX/RX-points can either be at different locations or co-sited but providing coverage in different sectors, and can also belong to the same or different base stations. For example, a TRP may be a transmission panel of a base station, which generally has a single transmission element. Thus, a base station may comprise a single TRP. Alternatively, a base station may comprise multiple TRPs.

Similarly, a serving cell can have multiple TRPs, with different TRPs for the same serving cell being located on different towers. For example, a serving cell may include a primary cell and any secondary cells, with each cell including one or more TRPs. A primary cell is a cell operating on a primary frequency in which the UE may perform an initial connection establishment procedure or initiates a connection re-establishment procedure with a base station. The primary cell may have a primary TRP for primarily receiving data from the UE and transmitting data to the UE. The primary cell may also have secondary TRPs for providing supplementary transmission and reception capability. Furthermore, a secondary cell may include its own primary and secondary TRPs which provide additional radio resources for a UE configured with carrier aggregation.

On top of secondary cells, a serving cell may include primary secondary cell group cells (PSCell) and special cells (SpCell) for dual connectivity operation. A primary secondary cell group cell is a cell in which a UE may perform random access with a base station when performing a reconfiguration with synchronization procedure. A special cell (SpCell) may be a primary cell (PCell) or a primary secondary cell group cell (PSCell). Thus, a serving cell may comprise a primary cell for UEs not configured with carrier aggregation or dual connectivity, while a serving cell may comprise any secondary cells or special cells for UEs configured with carrier aggregation or dual connectivity.

Different modes of multi-TRP (mTRP) operation may be supported in a wireless communication system. In a first mode (e.g. Mode 1), a single PDCCH is used to schedule a single PDSCH transport block (TB) from multiple TRPs in a serving cell.FIG.4illustrates an example400of Mode 1 multi-TRP operation. In the example ofFIG.4, a serving cell401may include multiple TRPs communicating with a UE402(e.g. TRP 1404and TRP 2406). TRP 1404may be a primary TRP, while TRP 2406may be a secondary TRP, or vice-versa. Both TRP 1404and TRP 2406may use a single PDCCH408(e.g. from the primary TRP) to coordinate their transmissions and schedule the same TB on their respective PDSCH410and412to UE402, thereby increasing data throughput. For example, the different TRPs may transmit the same data on PDSCH410and412using different spatial layers in overlapping resource blocks (RBs) or symbols (e.g. spatial division multiplexing [SDM], as illustrated inFIG.4), using different RBs in frequency (e.g. frequency division multiplexing [FDM]), or using different OFDM symbols (e.g. time division multiplexing [TDM]). Mode 1 multi-TRP operation generally requires ideal backhaul, or at least backhaul with small delay, between TRPs. Thus, TRP 1404and TRP 2406may be two sets of co-located TX/RX antennas (or two sets of one or more antenna arrays) of a single base station with ideal backhaul, or they may be from two different base stations with negligible or low latency in their coordination and transmission. Moreover, each TRP may communicate with the UE402using one or more beams. For example, TRP 1404may transmit PDCCH408to UE402using a PDCCH serving beam414.

In a second mode (e.g. Mode 2), multiple PDCCHs are used to schedule separate PDSCH TBs from multiple TRPs in a serving cell.FIG.5illustrates an example500of Mode 2 multi-TRP operation. In the example ofFIG.5, a serving cell501may include multiple TRPs in communication with a UE502(e.g. TRP 1504and TRP 2506). TRP 1504may be a primary TRP, while TRP 2506may be a secondary TRP, or vice-versa. TRPs504,506function independently by having their own PDCCH508,510for separately scheduling different TBs to UE502on different PDSCH512,514. Mode 2 multi-TRP operation may be supported for TRPs with both ideal and non-ideal backhaul (e.g. significant latency or delay in communications prohibiting synchronization of operation between TRPs). Thus, TRP 1504and TRP 2506may be two sets of co-located TX/RX antennas of a single base station, or antenna arrays of two different base stations. Moreover, each TRP may communicate with the UE502using one or more beams. For example, TRP 1504may transmit PDCCH508to UE502using a PDCCH serving beam516, while TRP 2506may transmit PDCCH510to UE502using another PDCCH serving beam518.

In Mode 2 multi-TRP operation, the separate PDCCH and PSDCHs may be served using different beams. For example, to support multiple PDCCH monitoring by the UE, multiple control resource set (CORESETs) may be configured per TRP (e.g. up to 3 CORESETs or some other number) up to a maximum number of CORESETS in total (e.g. up to 5 CORESETs or some other number), thus allowing each TRP to transmit their PDCCH using multiple beams. Moreover, with millimeter wave (mmW) beamforming, beams may be precisely configured to allow TRPs to send information to and receive information from the UE at high frequencies. However, such beams may easily fail or be lost, for example, in response to UE movement or due to sudden presence of an obstacle interfering with the beam. As a result, UEs generally perform a beam failure detection (BFD) procedure to keep track of possible failure of the PDCCH serving beam of each TRP.

FIG.6illustrates an example600of a BFD procedure performed by a UE602in communication with a TRP604of a base station. TRP604may correspond, for example, to TRP404ofFIG.4. In operation, TRP604provides to UE602one or more BFD reference-signal (RS) resources606over one or more PDCCH serving beams. In some aspects, only one PDCCH serving beam is implemented; in other aspects, TRP604may be configured with a second, wider PDCCH beam to allow for communication between the TRP604and UE602if the first PDCCH serving beam fails. For example, TRP604may configure up to two BFD RS resources respectively associated with each of the one or more PDCCH serving beams, and provide those RS resources to UE602. In one aspect, the BFD RS resources606may comprise periodic CSI-RS resource configuration indexes configured by TRP604and transmitted to the UE602(e.g. in a higher layer parameter failureDetectionResources or some other name).

Using the BFD RS resources, at block608, the UE can periodically measure a link quality of the PDCCH serving beam(s) to detect whether beam failure occurs. Alternatively, if TRP604does not provide BFD RS resources606for the UE to measure for link quality, the UE may instead measure CSI-RS resources periodically communicated over the one or more PDCCH serving beams which have a quasi-colocation (QCI) relationship with a beam the UE may use to monitor PDCCH. Based on the BFD RS resources606(or periodic CSI-RS resources), the physical (PHY) layer of the UE measures the link quality of the beams by identifying a reference signal received power (RSRP) of the RS resources and determining whether they are below a RSRP threshold preconfigured by TRP604.

If the link quality is determined to be below the threshold, the PHY layer of the UE sends a beam failure indication (or BFD indication) to an upper layer (e.g. the medium access control (MAC) layer) of the UE602. The MAC layer maintains a dynamic BFD counter, which the UE increments by one (at block610) whenever a BFD indication is received from the PHY layer. The MAC layer also maintains a timer, which resets the BFD counter to zero whenever a BFD indication is not received after a pre-configured time. When the counter reaches a preconfigured maximum value, the UE detects beam failure612of the PDCCH serving beam(s) associated with the BFD RS resources606. The UE602may then perform beam failure recovery at block614based on a set of candidate beams from which the UE can select a new beam, the details of which are described immediately below.

FIG.7illustrates an example700of a beam failure recovery procedure (occurring after the beam failure detection procedure ofFIG.6) which a UE702performs to recover its PDCCH serving beams. Initially prior to beam failure, a base station comprising TRP704configures a set of candidate beams at block706which the UE702may use to recover a PDCCH serving beam. The TRP704may correspond to TRP604ofFIG.6. The set of candidate beams may be a subset of a total set of beams transmitted by TRP704. For example, the set of candidate beams may include a number of adjacent beams directed towards the location of the UE (e.g. where beam failure had occurred), with each beam having an identical beamwidth to the failed beam and/or a wider beamwidth than the failed beam. In one aspect, the set of candidate beams may comprise periodic CSI-RS resource configuration indexes and/or SS/PBCH block indexes configured for the TRP704and which are transmitted to the UE702(e.g. in a higher layer parameter candidateBeamRSList or some other name). After the candidate beams are configured, the TRP704provides the set of candidate beams708to the UE702.

At block709, the UE702may detect failure of a PDCCH serving beam as described above with respect toFIG.6. For example, the UE702may detect that the PDCCH serving beam for TRP704has failed. Accordingly, the UE selects at block710a new beam from the set of candidate beams708to recover the PDCCH serving beam. The beam selection is based on link quality. For example, the UE702may measure the RSRP for each beam in the set of candidate beams (for example, based on CSI-RS associated with each beam), and select a new beam having a RSRP over a pre-configured threshold. If the serving cell in which beam failure is detected is a secondary cell (e.g. TRP704is in a secondary cell), the UE may indicate its preferred new beam to a base station in a primary cell at block712. For example, the UE702may send a medium access control (MAC) control element (CE) to a base station in the primary cell to reconfigure the new PDCCH beam for TRP704. The MAC CE may include the index of the secondary cell in which beam failure was detected, and the index of the UE's selected beam from the set of candidate beams.

The TRP704may also configure, at block714, physical random access channel (PRACH) resources for beam failure recovery and provide the PRACH configuration716to the UE. For example, the PRACH configuration may include a unique preamble configured for the UE702to use when performing a contention-free random access (CFRA) procedure to reacquire a connection with TRP704in the event of beam failure. Alternatively, the TRP704may not configure any PRACH resources for beam failure recovery, and the UE may perform a contention-based random access (CBRA) procedure to reacquire the connection with TRP704in the event of beam failure. If the serving cell in which beam failure occurs is a primary cell or a special cell, the UE may perform a CFRA or CBRA RACH procedure718to indicate its preferred new beam for the PDCCH to TRP704. In either CFRA or CBRA, each PRACH occasion may be associated with a respective beam in the set of candidate beams, and the PRACH configuration716may indicate the transmission occasions associated with each beam to the UE702.

Thus, in one aspect, if the UE702is configured with dedicated PRACH resources and identifies a new beam from the set of candidate beams with sufficient link quality (e.g. having a RSRP over a pre-configured threshold), the UE may perform CFRA with TRP704by initially transmitting a preamble in the PRACH occasion corresponding to the identified beam. For example, if the set of candidate beams is comprised of three beams, and beam two is of sufficient link quality, the UE may select beam two and transmit the preamble in the second transmission occasion (e.g. associated with beam two) within a PRACH configuration period. Upon completion of the RACH procedure, the TRP704may subsequently reconfigure its PDCCH serving beam to correspond to the UE's selected beam two.

Alternatively, if the UE702is unable to select a new beam from the set of candidate beams (none of the candidate beams have sufficient link quality or RSRP exceeding the preconfigured threshold), or the base station comprising TRP704does not configure dedicated PRACH resources to the UE for beam failure recovery, the UE may perform CBRA with TRP704over common PRACH resources. In this aspect, the UE may select a beam among a total set of beams transmitted by TRP704, e.g., based on synchronization signal blocks (SSBs) transmitted in the serving cell, and the UE may transmit a preamble in the PRACH transmission occasion corresponding to the identified beam. For example, the UE may select beam three based on a SSB received from TRP704and transmit a preamble in the third transmission occasion (e.g. associated with beam three) within a PRACH configuration period. Upon completion of the RACH procedure, the TRP704may subsequently reconfigure its PDCCH serving beam to correspond to the UE's selected beam three.

Thus, when detecting beam failure and performing beam failure recovery in Mode 1 multi-TRP operation, the UE has to track the serving beam(s) of only one PDCCH in a serving cell. However, in Mode 2 multi-TRP operation, the UE generally has to track the serving beam(s) of two PDCCH in a serving cell (e.g. one from each TRP) for beam failure detection and recovery. For example, one or more base stations may configure dedicated BFR PRACH resources and candidate beam sets for both TRPs, and the UE has to perform beam failure detection independently for each TRP based on beam failure reference signals associated with each TRP. Moreover, if strong candidate beams with sufficient link quality are unavailable and the serving cell is a primary or special cell, the UE may be required to perform CBRA for each TRP to recover the PDCCH serving beam for each TRP. This process not only requires additional resources compared to Mode 1 multi-TRP operation, but a longer delay in beam failure recovery time may be incurred. Hence, it would be helpful to enhance Mode 2 multi-TRP operation.

Aspects of the present disclosure enhance Mode 2 multi-TRP operation by allowing a UE to recover and reconfigure a failed PDCCH beam of a first TRP in a serving cell by using a second TRP which still has a working PDCCH in the same serving cell. For example, if the first TRP undergoes beam failure but the second TRP in the same cell has an operational beam, then rather than performing RACH on the first TRP, the UE may transmit a beam failure indication (e.g. a MAC CE) indicating a new beam for the PDCCH of the first TRP. The base station comprising the second TRP may then reconfigure the PDCCH serving beams of the first TRP based on the beam failure indication.

However, if the second TRP also undergoes beam failure while beam failure recovery is being performed for the first TRP, and the serving cell is a primary cell or a special cell, the UE only performs RACH on the primary TRP rather than both the primary TRP and secondary TRP. For instance, the UE may perform CFRA with the primary TRP to indicate a new beam if one or more candidate beams have sufficient link quality. Alternatively, the UE may perform CBRA with the primary TRP to indicate a new beam if no candidate beams have sufficient link quality. After the UE performs beam failure recovery using RACH on the primary TRP, the UE may perform beam failure recovery for the second TRP by transmitting a beam failure indication (e.g. a MAC CE). The base station comprising the primary TRP may then reconfigure the PDCCH serving beams of the secondary TRP based on the beam failure indication. Alternatively, if the serving cell is a secondary cell, the UE may simply transmit a beam failure indication (e.g. a MAC CE) in another secondary cell to reconfigure the failed PDCCH serving beam. The beam failure indication may include the index of the SCell where beam failure has occurred and the index of a selected candidate beam by the UE. As a result, the reliability of a serving cell may be increased.

FIG.8illustrates an example800of a beam failure detection and recovery procedure performed by a UE802in communication with a TRP804and TRP806in Mode 2 multi-TRP operation. TRP804may correspond, for example, to TRP504ofFIG.5, and TRP806may correspond, for example, to TRP506ofFIG.5within the same serving cell. One or more base stations comprising TRP804and/or TRP806may configure the TRP804to transmit one set of BFD RS resources808and TRP806to transmit another set of BFD RS resources810. TRP804and806may provide UE802the RS resources808,810over different PDCCH serving beams (e.g. PDCCH serving beams516and518). In one aspect, the BFD RS resources808,810may comprise periodic CSI-RS resource configuration indexes configured by TRP804,806and transmitted to the UE802(e.g. in higher layer parameters failureDetectionResources or some other name).

The one or more base stations comprising TRP804and/or TRP806may also configure each TRP with a set of candidate beams812,814which the UE802may respectively use to recover the PDCCH serving beam of each TRP804,806. TRP804and TRP806may each provide a beam failure recovery configuration816,818to the UE802including their respective sets of candidate beams. Each set of candidate beams may be a subset of the total set of beams transmitted by the respective TRP804,806. In one aspect, each set of candidate beams may comprise periodic CSI-RS resource configuration indexes and/or SS/PBCH block indexes (e.g. in a higher layer parameter candidateBeamRSList or some other name).

TRPs804,806may also provide a BFD PRACH configuration to the UE802. For example, assuming TRP804is the primary TRP, the base station comprising TRP804may configure PRACH resources820for the UE802to use for beam failure recovery of the PDCCH for TRP804. For example, the PRACH resources may include a unique preamble configured for the UE802to use when performing a CFRA procedure to reacquire a connection with TRP804. Alternatively, the TRP804may not configure any PRACH resources for beam failure recovery, and the UE may instead perform a CBRA procedure to reacquire the connection with TRP804in the event of beam failure of the primary TRP. In either type of procedure, the PRACH configuration822transmitted to the UE may include RACH transmission occasions associated with each beam in the set of candidate beams. Additionally, the primary TRP may provide the PRACH configuration822to the UE in the beam failure recovery configuration816(along with the set of candidate beams), rather than in a separate message as illustrated for example inFIG.8.

At block824, the UE802detects beam failure for each TRP804,806independently. For example, using the BFD RS resources808,810from each TRP804,806, the UE may periodically measure a link quality of the PDCCH serving beam(s) from each TRP to detect whether beam failure occurs at each TRP. Based on the BFD RS resources, the UE may determine whether an RSRP associated with each beam is below a RSRP threshold preconfigured by the one or more base stations comprising TRP804,806. If the link quality of a beam is below the threshold, the UE increments a dynamic BFD counter associated with the TRP transmitting the beam. When the counter reaches a preconfigured maximum value for a particular TRP, the UE detects beam failure of the PDCCH serving beam(s) from that TRP.

In this example, at block824, a beam failure may be detected for TRP804while the PDCCH serving beam of TRP806(in the same serving cell) is operational. Accordingly, in response to the beam failure detection, the UE802may perform beam failure recovery826to recover the PDCCH serving beam for the TRP804by transmitting a beam failure indication828. The beam failure indication828may be a MAC CE indicating a new beam which the UE802has selected based on link quality from the set of candidate beams received from TRP804. For example, when performing beam failure recovery826for the PDCCH of TRP804, the UE802may select at block830a new beam from TRP804's set of candidate beams and transmit the beam failure indication828. For instance, the UE802may measure the RSRP of each beam in the set of candidate beams, identify a new beam having a RSRP over a pre-configured threshold, and subsequently transmit the index of that selected beam in the MAC CE.

The base station comprising TRP806may receive the beam failure indication828and then reconfigure the PDCCH as well as the PDSCH beam for TRP804using the PDCCH and PSDCH of TRP806. For example, TRP806may send to the UE802a transmission configuration indicator (TCI) state indication832for a UE-specific PDCCH MAC CE and a TCI state activation indicator834(activation/deactivation) for a UE-specific PDSCH MAC CE. Based on the TCI state indicator832and/or TCI state activation indicator834, the UE may communicate with TRP804using the new beam.

In certain aspects, another beam failure may be detected for TRP806at block836while the UE is still performing beam failure recovery826for the PDCCH of TRP804. In such case, the UE802may perform another beam failure recovery838to recover the PDCCH of TRP806at the same time as it performs beam failure recovery826to recover the PDCCH of TRP804. In one example, the serving cell in which beam failures are detected at blocks824and836may be a secondary cell. In such case, when performing beam failure recovery838for the PDCCH of TRP806, the UE802may select a new beam at block840from the set of candidate beams for TRP806and transmit a beam failure indication842(e.g. a MAC CE) in another secondary cell (e.g. including a third TRP844whose PDCCH beam is currently in operation). The MAC CE may include the index of the secondary cell in which beam failure was detected, and the index of the UE's selected beam from the set of candidate beams. The base station comprising TRP844may receive the beam failure indication842and then reconfigure the PDCCH as well as the PDSCH beam for TRP806(or TRP804) using the PDCCH and PSDCH of TRP806as described above.

In another example, the serving cell in which beam failures are detected at blocks824and836may be a primary cell or a special cell. In such case, the UE802may perform beam recovery for the PDCCH of the primary TRP as described above with respect toFIG.7. For example, if TRP806is the primary TRP, the UE may perform a CFRA or CBRA RACH procedure846with TRP806based on the beam failure recovery configuration818(or PRACH resources). In either procedure, the UE may transmit a preamble in the PRACH transmission occasion corresponding to the identified beam to indicate its preferred new beam for the PDCCH of the primary TRP. After successfully completing beam failure recovery on the primary TRP (e.g. TRP806), the UE may then transmit a beam failure indication848(e.g. a MAC CE) for the primary TRP to reconfigure the PDCCH beam for the secondary TRP (e.g. TRP804) using the PDCCH and PDSCH of TRP806as described above.

FIG.9is a flowchart900of a method of wireless communication. The method may be performed by a UE (e.g., the UE104,350,402,502,602,702,802; the apparatus1002/1002′; the processing system1114, which may include the memory360and which may be the entire UE350or a component of the UE350, such as the TX processor368, the RX processor356, and/or the controller/processor359). Optional aspects are illustrated in dashed lines.

At902, the UE receives data from a first transmission reception point (TRP) and a second TRP in a serving cell based on a physical downlink control channel (PDCCH) of the first TRP and the second TRP, the PDCCH of the first TRP and second TRP each received over separate beams. For example,902may be performed by PDCCH component1006inFIG.10. For instance, referring toFIG.5, a serving cell501may include multiple TRPs in communication with a UE502(e.g. TRP 1504and TRP 2506). Each TRP may communicate with the UE502using one or more beams. For example, TRP 1504may transmit PDCCH508to UE502using a PDCCH serving beam516, while TRP 2506may transmit PDCCH510to UE502using another PDCCH serving beam518.

At904, the UE detects beam failure of the PDCCH of the first TRP. For example,904may be performed by detection component1008inFIG.10. The beam failure may be detected based on one or more reference signals received from the first TRP and the second TRP. The beam failure is detected for the first TRP independently from the second TRP. For example, referring toFIG.8, one or more base stations comprising TRP804and/or TRP806may configure the TRP804to transmit one set of BFD RS resources808and TRP806to transmit another set of BFD RS resources810. At block824, the UE802detects beam failure for each TRP804,806independently. For example, using the BFD RS resources808,810from each TRP804,806, the UE may periodically measure a link quality of the PDCCH serving beam(s) from each TRP to detect whether beam failure occurs at each TRP. Based on the BFD RS resources, the UE may determine whether an RSRP associated with each beam is below a RSRP threshold preconfigured by the one or more base stations comprising TRP804,806. If the link quality of a beam is below the threshold, the UE increments a dynamic BFD counter associated with the TRP transmitting the beam. When the counter reaches a preconfigured maximum value for a particular TRP, the UE detects beam failure of the PDCCH serving beam(s) from that TRP.

At906, the UE performs beam failure recovery for the first TRP by transmitting a beam failure indication indicating a new beam for the PDCCH of the first TRP. For example,906may be performed by recovery component1010inFIG.10. The beam failure recovery may be performed based on a beam failure recovery configuration comprising a set of candidate beams for the first TRP and the second TRP. In one aspect, beam failure recovery may be performed for the PDCCH of the first TRP while the beam for the PDCCH of the second TRP is operational. In this aspect, the beam failure indication comprises a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the first TRP. For example, referring toFIG.8, the one or more base stations comprising TRP804and/or TRP806may configure each TRP with a set of candidate beams812,814which the UE802may respectively use to recover the PDCCH serving beam of each TRP804,806. TRP804and TRP806may each provide a beam failure recovery configuration816,818to the UE802including their respective sets of candidate beams. In this example, at block824, a beam failure may be detected for TRP804while the PDCCH serving beam of TRP806(in the same serving cell) is operational. Accordingly, in response to the beam failure detection, the UE802may perform beam failure recovery826to recover the PDCCH serving beam for the TRP804by transmitting a beam failure indication828. The beam failure indication828may be a MAC CE indicating a new beam which the UE802has selected based on link quality from the set of candidate beams received from TRP804.

Beam failure recovery may be performed for the PDCCH of the first TRP based on a transmission configuration indicator (TCI) state indication for a UE-specific PDCCH MAC CE received from the second TRP. Beam failure recovery may be further performed for a physical downlink shared channel (PDSCH) of the first TRP based on a transmission configuration indicator (TCI) state activation indication for a UE-specific PDSCH MAC CE received from the second TRP. For example, referring toFIG.8, the base station comprising TRP806may receive the beam failure indication828and then reconfigure the PDCCH as well as the PDSCH beam for TRP804using the PDCCH and PSDCH of TRP806. For example, TRP806may send to the UE802a transmission configuration indicator (TCI) state indication832for a UE-specific PDCCH MAC CE and a TCI state activation indicator834(activation/deactivation) for a UE-specific PDSCH MAC CE. Based on the TCI state indicator832and/or TCI state activation indicator834, the UE may communicate with TRP804using the new beam.

In another aspect, at908, the UE may detect beam failure of the PDCCH of the second TRP. For example,908may be performed by detection component1008inFIG.10. For example, referring toFIG.8, another beam failure may be detected as described above, but for TRP806at block836while the UE is still performing beam failure recovery826for the PDCCH of TRP804.

Accordingly, at910, the UE may perform beam failure recovery for the PDCCH of the second TRP at the same time as the first TRP. For example,910may be performed by recovery component1010inFIG.10. In one aspect, the serving cell comprises a secondary cell, and the beam failure recovery is performed for the PDCCH of the second TRP by transmitting a beam failure indication in a different secondary cell. The beam failure indication comprises a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the second TRP. For example, referring toFIG.8, the UE802may perform another beam failure recovery838to recover the PDCCH of TRP806at the same time as it performs beam failure recovery826to recover the PDCCH of TRP804. In one example, the serving cell in which beam failures are detected at blocks824and836may be a secondary cell. In such case, when performing beam failure recovery838for the PDCCH of TRP806, the UE802may select a new beam at block840from the set of candidate beams for TRP806and transmit a beam failure indication842(e.g. a MAC CE) in another secondary cell (e.g. including a third TRP844whose PDCCH beam is currently in operation). The MAC CE may include the index of the secondary cell in which beam failure was detected, and the index of the UE's selected beam from the set of candidate beams. The base station comprising TRP844may receive the beam failure indication842and then reconfigure the PDCCH as well as the PDSCH beam for TRP806(or TRP804) using the PDCCH and PSDCH of TRP806as described above.

In another aspect, the serving cell comprises a special cell, and the special cell comprises one of a primary cell or a primary secondary cell group cell. In this aspect, at912, the UE may perform a random access channel (RACH) procedure indicating a new beam for a PDCCH of the primary TRP. For example,912may be performed by RACH component1014inFIG.10. A physical RACH (PRACH) preamble is transmitted in a PRACH occasion associated with the new beam during the RACH procedure. The first TRP may comprise a primary TRP, and the second TRP may comprise a secondary TRP. For example, referring toFIG.8, the serving cell in which beam failures are detected at blocks824and836may be a primary cell or a special cell. In such case, the UE802may perform beam recovery for the PDCCH of the primary TRP as described above with respect toFIG.7. For example, if TRP806is the primary TRP, the UE may perform a CFRA or CBRA RACH procedure846with TRP806based on the beam failure recovery configuration818(or PRACH resources). In either procedure, the UE may transmit a preamble in the PRACH transmission occasion corresponding to the identified beam to indicate its preferred new beam for the PDCCH of the primary TRP.

FIG.10is a conceptual data flow diagram1000illustrating the data flow between different means/components in an example apparatus1002. The apparatus may be a UE (e.g. the UE104,350,402,502,602,702,802) in communication with one or more base stations1050,1060(e.g. base station102/180,310) comprising one or more TRPs (e.g. TRP404,406,504,506,604,704,804,806). The apparatus includes a reception component1004that is configured to receive downlink communications from one or more TRPs. The apparatus includes a PDCCH component1006that is configured to receive data from a first transmission reception point (TRP) and a second TRP in a serving cell based on a physical downlink control channel (PDCCH) of the first TRP and the second TRP, the PDCCH of the first TRP and second TRP each received over separate beams, e.g., as described in connection with902inFIG.9. The apparatus includes a detection component1008that is configured to detecting beam failure of the PDCCH of the first TRP, e.g., as described in connection with904inFIG.9. The detection component1008is also configured to detect beam failure of the PDCCH of the second TRP, e.g., as described in connection with908inFIG.9. The apparatus includes a recovery component1010that is configured to perform beam failure recovery for the first TRP by transmitting a beam failure indication indicating a new beam for the PDCCH of the first TRP, e.g., as described in connection with906inFIG.9. The recovery component1010is also configured to perform beam failure recovery for the PDCCH of the second TRP at the same time as the first TRP, e.g., as described in connection with910inFIG.9. The apparatus includes a transmission component1012that is configured to transmit uplink communications to the one or more base stations. The apparatus includes a RACH component1014that is configured to perform a random access channel (RACH) procedure indicating a new beam for a PDCCH of the primary TRP, e.g., as described in connection with912inFIG.9.

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowchart ofFIG.9. As such, each block in the aforementioned flowchart ofFIG.9may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG.11is a diagram1100illustrating an example of a hardware implementation for an apparatus1002′ employing a processing system1114. The processing system1114may be implemented with a bus architecture, represented generally by the bus1124. The bus1124may include any number of interconnecting buses and bridges depending on the specific application of the processing system1114and the overall design constraints. The bus1124links together various circuits including one or more processors and/or hardware components, represented by the processor1104, the components1004,1006,1008,1010,1012,1014and the computer-readable medium/memory1106. The bus1124may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1114may be coupled to a transceiver1110. The transceiver1110is coupled to one or more antennas1120. The transceiver1110provides a means for communicating with various other apparatus over a transmission medium. The transceiver1110receives a signal from the one or more antennas1120, extracts information from the received signal, and provides the extracted information to the processing system1114, specifically the reception component1004. In addition, the transceiver1110receives information from the processing system1114, specifically the transmission component1012, and based on the received information, generates a signal to be applied to the one or more antennas1120. The processing system1114includes a processor1104coupled to a computer-readable medium/memory1106. The processor1104is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1106. The software, when executed by the processor1104, causes the processing system1114to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1106may also be used for storing data that is manipulated by the processor1104when executing software. The processing system1114further includes at least one of the components1004,1006,1008,1010,1012,1014. The components may be software components running in the processor1104, resident/stored in the computer readable medium/memory1106, one or more hardware components coupled to the processor1104, or some combination thereof. The processing system1114may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359. Alternatively, the processing system1114may be the entire UE (e.g., see350ofFIG.3).

In one configuration, the apparatus1002/1002′ for wireless communication includes means for receiving data from a first transmission reception point (TRP) and a second TRP in a serving cell based on a physical downlink control channel (PDCCH) of the first TRP and the second TRP, the PDCCH of the first TRP and second TRP each received over separate beams; means for detecting beam failure of the PDCCH of the first TRP; and means for performing beam failure recovery for the first TRP by transmitting a beam failure indication indicating a new beam for the PDCCH of the first TRP. In one configuration, the means for detecting may be further configured to detect beam failure of the PDCCH of the second TRP. In one configuration, the means for performing may be further configured to perform beam failure recovery for the PDCCH of the second TRP at the same time as the first TRP. In one configuration, the apparatus may also include means for performing a random access channel (RACH) procedure indicating a new beam for a PDCCH of the primary TRP.

The aforementioned means may be one or more of the aforementioned components of the apparatus1002and/or the processing system1114of the apparatus1002′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1114may include the TX Processor368, the RX Processor356, and the controller/processor359. As such, in one configuration, the aforementioned means may be the TX Processor368, the RX Processor356, and the controller/processor359configured to perform the functions recited by the aforementioned means.

FIG.12is a flowchart1200of a method of wireless communication. The method may be performed by a base station (e.g., the base station102/180,310; the apparatus1302/1302′; the processing system1414, which may include the memory376and which may be the entire base station310or a component of the base station310, such as the TX processor316, the RX processor370, and/or the controller/processor375). The base station may communicate with a first TRP in a serving cell (e.g., the TRPs404,504,804), and the base station may comprise a second TRP in the serving cell (e.g. the TRPs406,506,806). The base station may alternatively comprise the first TRP and second TRP. Optional aspects are illustrated in dashed lines.

At1202, the base station transmits data to a user equipment (UE) based on a physical downlink control channel (PDCCH) of the second TRP, wherein the PDCCH of the second TRP is transmitted to the UE over a separate beam than a PDCCH of the first TRP. For example,1202may be performed by beam component1314inFIG.13. For instance, referring toFIG.5, a serving cell501may include multiple TRPs in communication with a UE502(e.g. TRP 1504and TRP 2506). Each TRP may communicate with the UE502using one or more beams. For example, TRP 1504may transmit PDCCH508to UE502using a PDCCH serving beam516, while TRP 2506may transmit PDCCH510to UE502using another PDCCH serving beam518.

At1204, the base station receives a beam failure indication from the UE in response to a beam failure of the PDCCH of the first TRP. For example,1204may be performed by beam failure component1306inFIG.13. The beam failure indication may be received based on one or more reference signals of the first TRP and the second TRP. The beam failure indication may comprise a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the first TRP. In one aspect, the new beam is configured for the PDCCH of the first TRP while the beam for the PDCCH of the second TRP is operational. For example, referring toFIG.8, one or more base stations comprising TRP804and/or TRP806may configure the TRP804to transmit one set of BFD RS resources808and TRP806to transmit another set of BFD RS resources810. At block824, the UE802detects beam failure for each TRP804,806independently. For example, using the BFD RS resources808,810from each TRP804,806, the UE may periodically measure a link quality of the PDCCH serving beam(s) from each TRP to detect whether beam failure occurs at each TRP. In this example, at block824, a beam failure may be detected for TRP804while the PDCCH serving beam of TRP806(in the same serving cell) is operational. Accordingly, in response to the beam failure detection, the UE802may perform beam failure recovery826to recover the PDCCH serving beam for the TRP804by transmitting a beam failure indication828. The beam failure indication828may be a MAC CE indicating a new beam which the UE802has selected based on link quality from the set of candidate beams received from TRP804. The base station comprising TRP806may receive the beam failure indication828.

At1206, the base station configures a new beam for the PDCCH of the first TRP based on the beam failure indication. For example,1206may be performed by configuration component1308inFIG.13. The new beam may be configured based on a beam failure recovery configuration comprising a set of candidate beams for the first TRP and the second TRP. The new beam may be configured for the PDCCH of the first TRP based on a transmission configuration indicator (TCI) state indication for a UE-specific PDCCH MAC CE transmitted from the second TRP. Another beam may also be configured for a physical downlink shared channel (PDSCH) of the first TRP based on a transmission configuration indicator (TCI) state activation indication for a UE-specific PDSCH MAC CE transmitted from the second TRP. For example, referring toFIG.8, the one or more base stations comprising TRP804and/or TRP806may configure each TRP with a set of candidate beams812,814which the UE802may respectively use to recover the PDCCH serving beam of each TRP804,806. TRP804and TRP806may each provide a beam failure recovery configuration816,818to the UE802including their respective sets of candidate beams. The base station comprising TRP806may receive the beam failure indication828and then reconfigure the PDCCH as well as the PDSCH beam for TRP804using the PDCCH and PSDCH of TRP806. For example, TRP806may send to the UE802a transmission configuration indicator (TCI) state indication832for a UE-specific PDCCH MAC CE and a TCI state activation indicator834(activation/deactivation) for a UE-specific PDSCH MAC CE. Based on the TCI state indicator832and/or TCI state activation indicator834, the UE may communicate with TRP804using the new beam.

In another aspect, at1208, the base station receives a configuration of a new beam for the PDCCH of the second TRP in response to a beam failure of the PDCCH of the second TRP, the beam failure occurring before the new beam for the PDCCH of the first TRP is configured. For example,1208may be performed by new beam component1312inFIG.13. In one aspect, the serving cell comprises a secondary cell, and the configuration of the new beam is received from a third TRP in a different secondary cell. For example, referring toFIG.8, another beam failure may be detected as described above, but for TRP806at block836while the UE is still performing beam failure recovery826for the PDCCH of TRP804. In one example, the serving cell in which beam failures are detected at blocks824and836may be a secondary cell. In such case, when performing beam failure recovery838for the PDCCH of TRP806, the UE802may select a new beam at block840from the set of candidate beams for TRP806and transmit a beam failure indication842(e.g. a MAC CE) in another secondary cell (e.g. including a third TRP844whose PDCCH beam is currently in operation). The MAC CE may include the index of the secondary cell in which beam failure was detected, and the index of the UE's selected beam from the set of candidate beams. The base station comprising TRP844may receive the beam failure indication842and then reconfigure the PDCCH as well as the PDSCH beam for TRP806(or TRP804) using the PDCCH and PSDCH of TRP806as described above.

In another aspect, the serving cell comprises a special cell, and the special cell comprises one of a primary cell or a primary secondary cell group cell. In such case, the first TRP comprises a primary TRP, the second TRP comprises a secondary TRP, and the configuration of the new beam is received from the primary TRP.

Alternatively, the second TRP may comprise the primary TRP, and the configuration of the new beam is based on a physical random access channel (PRACH) preamble received in a PRACH occasion associated with the new beam. For example, referring toFIG.8, the serving cell in which beam failures are detected at blocks824and836may be a primary cell or a special cell. In such case, the UE802may perform beam recovery for the PDCCH of the primary TRP as described above with respect toFIG.7. For example, if TRP806is the primary TRP, the UE may perform a CFRA or CBRA RACH procedure846with TRP806based on the beam failure recovery configuration818(or PRACH resources). In either procedure, the UE may transmit a preamble in the PRACH transmission occasion corresponding to the identified beam to indicate its preferred new beam for the PDCCH of the primary TRP. After successfully completing beam failure recovery on the primary TRP (e.g. TRP806), the UE may then transmit a beam failure indication848(e.g. a MAC CE) for the primary TRP to reconfigure the PDCCH beam for the secondary TRP (e.g. TRP804) using the PDCCH and PDSCH of TRP806as described above.

FIG.13is a conceptual data flow diagram1300illustrating the data flow between different means/components in an example apparatus1302. The apparatus may be a base station (e.g. base station102/180,310) which may communicate with a first TRP in a serving cell (e.g., the TRPs404,504,804), and may comprise a second TRP in the serving cell (e.g. the TRPs406,506,806). The base station may also comprise the first and second TRPs. The apparatus includes a reception component1304that is configured to receive uplink communications from a UE1360(e.g. UE104,350,402,502,602,702,802) as well as communications from other base stations/TRPs1350. The apparatus includes a transmission component1310that is configured to transmit downlink communications to the UE as well as communications to other base stations/TRPs. The apparatus includes a beam component1314that is configured to transmit data to a user equipment (UE) based on a physical downlink control channel (PDCCH) of the second TRP, where the PDCCH of the second TRP is transmitted to the UE over a separate beam than a PDCCH of the first TRP, e.g., as described in connection with1202ofFIG.12. The apparatus includes a beam failure component1306which is configured to receive a beam failure indication from the UE in response to a beam failure of the PDCCH of the first TRP, e.g., as described in connection with1204ofFIG.12. The apparatus includes a configuration component1308which configures a new beam for the PDCCH of the first TRP based on the beam failure indication, e.g., as described in connection with1206ofFIG.12. The apparatus includes a new beam component1312that receives a configuration of a new beam for the PDCCH of the second TRP in response to a beam failure of the PDCCH of the second TRP, the beam failure occurring before the new beam for the PDCCH of the first TRP is configured, e.g., as described in connection with1208ofFIG.12.

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowchart ofFIG.13. As such, each block in the aforementioned flowchart ofFIG.13may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG.14is a diagram1400illustrating an example of a hardware implementation for an apparatus1302′ employing a processing system1414. The processing system1414may be implemented with a bus architecture, represented generally by the bus1424. The bus1424may include any number of interconnecting buses and bridges depending on the specific application of the processing system1414and the overall design constraints. The bus1424links together various circuits including one or more processors and/or hardware components, represented by the processor1404, the components1304,1306,1308,1310,1312,1314and the computer-readable medium/memory1406. The bus1424may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1414may be coupled to a transceiver1410. The transceiver1410is coupled to one or more antennas1420. The transceiver1410provides a means for communicating with various other apparatus over a transmission medium. The transceiver1410receives a signal from the one or more antennas1420, extracts information from the received signal, and provides the extracted information to the processing system1414, specifically the reception component1304. In addition, the transceiver1410receives information from the processing system1414, specifically the transmission component1310, and based on the received information, generates a signal to be applied to the one or more antennas1420. The processing system1414includes a processor1404coupled to a computer-readable medium/memory1406. The processor1404is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1406. The software, when executed by the processor1404, causes the processing system1414to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1406may also be used for storing data that is manipulated by the processor1404when executing software. The processing system1414further includes at least one of the components1304,1306,1308,1310,1312,1314. The components may be software components running in the processor1404, resident/stored in the computer readable medium/memory1406, one or more hardware components coupled to the processor1404, or some combination thereof. The processing system1414may be a component of the base station310and may include the memory376and/or at least one of the TX processor316, the RX processor370, and the controller/processor375. Alternatively, the processing system1414may be the entire base station (e.g., see310ofFIG.3).

In one configuration, the apparatus1302/1302′ for wireless communication includes means for transmitting data to a user equipment (UE) based on a physical downlink control channel (PDCCH) of the second TRP, wherein the PDCCH of the second TRP is transmitted to the UE over a separate beam than a PDCCH of the first TRP; means for receiving a beam failure indication from the UE in response to a beam failure of the PDCCH of the first TRP; and means for configuring a new beam for the PDCCH of the first TRP based on the beam failure indication. In one configuration, the apparatus may also include means for receiving a configuration of a new beam for the PDCCH of the second TRP in response to a beam failure of the PDCCH of the second TRP, the beam failure occurring before the new beam for the PDCCH of the first TRP is configured.

The aforementioned means may be one or more of the aforementioned components of the apparatus1302and/or the processing system1414of the apparatus1302′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1414may include the TX Processor316, the RX Processor370, and the controller/processor375. As such, in one configuration, the aforementioned means may be the TX Processor316, the RX Processor370, and the controller/processor375configured to perform the functions recited by the aforementioned means.

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

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Terms such as “if,” “when,” and “while” should be interpreted to mean “under the condition that” rather than imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when,” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”

The following examples are illustrative only and may be combined with aspects of other embodiments or teachings described herein, without limitation.

Example 1 is a method of wireless communication at a UE, comprising: receiving data from a first transmission reception point (TRP) and a second TRP in a serving cell based on a physical downlink control channel (PDCCH) of the first TRP and the second TRP, the PDCCH of the first TRP and second TRP each received over separate beams; detecting beam failure of the PDCCH of the first TRP; and performing beam failure recovery for the first TRP by transmitting a beam failure indication indicating a new beam for the PDCCH of the first TRP.

Example 2 is the method of Example 1, wherein the beam failure is detected based on one or more reference signals received from the first TRP and the second TRP.

Example 3 is the method of any of Examples 1 and 2, wherein the beam failure recovery is performed based on a beam failure recovery configuration comprising a set of candidate beams for the first TRP and the second TRP.

Example 4 is the method of any of Examples 1 to 3, wherein the beam failure is detected for the first TRP independently from the second TRP.

Example 5 is the method of any of Examples 1 to 4, wherein beam failure recovery is performed for the PDCCH of the first TRP while a beam for the PDCCH of the second TRP is operational.

Example 6 is the method of any of Examples 1 to 5, wherein the beam failure indication comprises a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the first TRP, and wherein beam failure recovery is performed for the PDCCH of the first TRP based on a transmission configuration indicator (TCI) state indication for a UE-specific PDCCH MAC CE received from the second TRP.

Example 7 is the method of any of Examples 1 to 6, wherein the beam failure indication comprises a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the first TRP, and wherein beam failure recovery is further performed for a physical downlink shared channel (PDSCH) of the first TRP based on a transmission configuration indicator (TCI) state activation indication for a UE-specific PDSCH MAC CE received from the second TRP.

Example 8 is the method of any of Examples 1 to 7, further comprising: detecting beam failure of the PDCCH of the second TRP; and performing beam failure recovery for the PDCCH of the second TRP at the same time as the first TRP.

Example 9 is the method of any of Examples 1 to 8, wherein the serving cell comprises a secondary cell, wherein the beam failure recovery is performed for the PDCCH of the second TRP by transmitting a beam failure indication in a different secondary cell, and wherein the beam failure indication comprises a medium access control (MAC) control element (CE) indicating a new beam for the PDCCH of the second TRP.

Example 10 is the method of any of Examples 1 to 9, wherein the serving cell comprises a special cell, and wherein the special cell comprises one of a primary cell or a primary secondary cell group cell.

Example 11 is the method of any of Examples 1 to 10, wherein the first TRP comprises a primary TRP, and wherein the second TRP comprises a secondary TRP, the method further comprising: performing a random access channel (RACH) procedure indicating a new beam for a PDCCH of the primary TRP, wherein a physical RACH (PRACH) preamble is transmitted in a PRACH occasion associated with the new beam during the RACH procedure.

Example 12 is a device including one or more processors and one or more memories in electronic communication with the one or more processors storing instructions executable by the one or more processors to cause the system or apparatus to implement a method as in any of Examples 1-11.

Example 13 is a system or apparatus including means for implementing a method or realizing an apparatus as in any of Examples 1-11.

Example 14 is a non-transitory computer readable medium storing instructions executable by one or more processors to cause the one or more processors to implement a method as in any of Examples 1-11.

Example 15 is a method of wireless communication at a base station in communication with a first transmission reception point (TRP) in a serving cell, the base station comprising a second TRP in the serving cell, the method comprising: transmitting data to a user equipment (UE) based on a physical downlink control channel (PDCCH) of the second TRP, wherein the PDCCH of the second TRP is transmitted to the UE over a separate beam than a PDCCH of the first TRP; receiving a beam failure indication from the UE in response to a beam failure of the PDCCH of the first TRP; and configuring a new beam for the PDCCH of the first TRP based on the beam failure indication.

Example 16 is the method of Example 15, wherein the beam failure indication is received based on one or more reference signals of the first TRP and the second TRP.

Example 17 is the method of any of Examples 15 and 16, wherein the new beam is configured based on a beam failure recovery configuration comprising a set of candidate beams for the first TRP and the second TRP.

Example 18 is the method of any of Examples 15 to 17, wherein the new beam is configured for the PDCCH of the first TRP while the beam for the PDCCH of the second TRP is operational.

Example 19 is the method of any of Examples 15 to 18, wherein the beam failure indication comprises a medium access control (MAC) control element (CE) indicating the new beam for the PDCCH of the first TRP, and wherein the new beam is configured for the PDCCH of the first TRP based on a transmission configuration indicator (TCI) state indication for a UE-specific PDCCH MAC CE transmitted from the second TRP.

Example 20 is the method of any of Examples 15 to 19, wherein the beam failure indication comprises a medium access control (MAC) control element (CE) indicating the new beam for the PDCCH of the first TRP, and wherein another beam is configured for a physical downlink shared channel (PDSCH) of the first TRP based on a transmission configuration indicator (TCI) state activation indication for a UE-specific PDSCH MAC CE transmitted from the second TRP.

Example 21 is the method of any of Examples 15 to 20, further comprising: receiving a configuration of a new beam for the PDCCH of the second TRP in response to a beam failure of the PDCCH of the second TRP, the beam failure occurring before the new beam for the PDCCH of the first TRP is configured.

Example 22 is the method of any of Examples 15 to 21, wherein the serving cell comprises a secondary cell, and wherein the configuration of the new beam for the PDCCH of the second TRP is received from a third TRP in a different secondary cell.

Example 23 is the method of any of Examples 15 to 22, wherein the first TRP comprises a primary TRP, wherein the second TRP comprises a secondary TRP, and wherein the configuration of the new beam for the PDCCH of the secondary TRP is received from the primary TRP.

Example 24 is the method of any of Examples 15 to 23, wherein the second TRP comprises a primary TRP, and wherein the configuration of the new beam for the PDCCH of the primary TRP is based on a physical random access channel (PRACH) preamble received in a PRACH occasion associated with the new beam for the PDCCH of the primary TRP.

Example 25 is a device including one or more processors and one or more memories in electronic communication with the one or more processors storing instructions executable by the one or more processors to cause the system or apparatus to implement a method as in any of Examples 15-24.

Example 26 is a system or apparatus including means for implementing a method or realizing an apparatus as in any of Examples 15-24.

Example 27 is a non-transitory computer readable medium storing instructions executable by one or more processors to cause the one or more processors to implement a method as in any of Examples 15-24.