Patent ID: 12224839

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 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 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 backhaul links134(e.g., X2 interface). The 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, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP)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 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. Communications using the mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz) has extremely high path loss and a short range. The mmW base station180may utilize beamforming182with the UE104to compensate for the extremely high path loss and short range.

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 PS Streaming Service, and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved 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 base station180may be configured to transmit an indication of a beam correspondence failure to a UE (e.g., UE104) when a difference between a first direction of a transmit beam formed at a transmit (Tx) antenna array and a second direction of a receive beam formed at a receive (Rx) antenna array is greater than or equal to a beam correspondence threshold (198). 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 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 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 X 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 μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 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 2μ*15 kKz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 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=0 with 1 slot per subframe. The subcarrier spacing is 15 kHz and symbol duration is approximately 66.7 μs.

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 100× 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 primary synchronization signal (PSS) may be within symbol2of 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 symbol4of 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. 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. Although not shown, the UE may transmit sounding reference signals (SRS). 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 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 processor316, the RX processor370, and the controller/processor375may be configured to perform aspects in connection with198ofFIG.1.

The concept of beam correspondence assumes that the optimum downlink (DL) transmitter/receiver beam pair between two wireless communication devices is also the optimum uplink (UL) transmitter/receiver beam pair with some radio frequency (RF) level adjustment of beam weights to capture calibration errors between DL and UL circuitry. Accordingly, a wireless communication device (e.g., a base station, a UE) may implement a beam correspondence feature in a wireless communication network (e.g., a 5G NR network) to determine beam weights for a receive beam (e.g., for receiving uplink (UL) signals or (DL) signals) based on one or more measurements of a transmit beam (e.g., for transmitting downlink (DL) signals or (UL) signals), or to determine beam weights for a transmit beam based on one or more measurements of a receive beam.

For example, a base station may receive a report from a UE indicating the signal strengths (e.g., reference signal received power (RSRP) measurements) of DL transmit beams formed at the base station and may determine the best DL transmit beam based on the report. The base station may assume channel reciprocity between the base station and the UE and may determine the beam weights for steering the direction of a UL receive beam based on the best DL transmit beam and RF/antenna asymmetries. The base station may then use the beam weights to form a UL receive beam to receive wireless communications from the UE. In this example, since the direction of the DL transmit beam corresponds to the direction of the UL receive beam, the DL transmit beam and the UL receive beam may be said to have beam correspondence.

Therefore, by forming the UL receive beam based on the DL transmit beam, the base station may avoid a separate beam training procedure for the UL receive beam and may avoid delays resulting from such separate beam training procedure. This also leads to power savings since a separate beam training procedure is avoided. It should be noted that in some low-tier devices (e.g., UEs with reduced capabilities relative to premium UEs, such as smartphones), beam correspondence capability may not be available. This may increase signaling overhead due to the need for separate UL and DL beam training procedures.

In an antenna array that includes a transmit antenna array and a receive antenna array, some components of the transmit antenna array (e.g., transmit (Tx) antenna elements) and some components of the receive antenna array (e.g., receive (Rx) antenna elements), may be co-located. However, the high power consumption and increased operating temperatures of the co-located Tx and Rx antenna elements in the antenna array may be difficult to manage and may compromise the operation and/or the longevity of the antenna array. These effects may be exacerbated as the size of the antenna array (e.g., the number of co-located Tx and Rx antenna elements forming the antenna array) and/or the carrier frequency increases. Moreover, feed-line crossings in an antenna array including co-located Tx and Rx antenna elements may significantly increase circuit design complexity as the size of the antenna array increases.

To avoid or reduce the previously discussed drawbacks associated with co-located Tx and Rx antenna elements, the Tx antenna elements and the Rx antenna elements may not be co-located (also referred to as non-co-located Tx and RX antenna elements or separated Tx and RX antenna elements). For example, the Tx antenna elements may be separated from the Rx antenna elements, such that the Tx antenna elements are situated apart from the Rx antenna elements. In some examples, antenna arrays with non-co-located Tx and Rx antenna elements may be implemented in wireless communication devices that may accommodate large antenna arrays, such as base stations, customer premises equipments (CPEs), and/or integrated access and backhaul (JAB) nodes. In some examples, antenna arrays with non-co-located Tx and Rx antenna elements may be implemented in wireless communication devices that may not have space for accommodating antenna arrays with large footprints, such as UEs and/or CPEs, when the wireless communication devices are configured to operate at higher frequency bands (e.g., FR4 or greater).

FIG.4illustrates separate Tx and Rx antenna arrays, such as the Tx antenna array400and the Rx antenna array450. The Tx antenna array400includes a set of Tx antenna elements, such as Tx antenna elements402,404,406,408,410,412. In some examples, each of the Tx antenna elements in the Tx antenna array400may be approximately equal in size and may be described as to be in a square shape (even though the actual antenna element may be in a different shape), such as the Tx antenna element402with side dimension403. The Tx antenna elements in each column (e.g., Tx antenna elements402,404,406) of the Tx antenna array400may have uniform spacing and may be spaced apart by a center-to-center distance418(also referred to as inter-antenna element spacing418). The Tx antenna elements in each row (e.g., Tx antenna elements402,408,410,412) of the Tx antenna array400may have uniform spacing and may be spaced apart by a center-to-center distance420(also referred to as inter-antenna element spacing420). As shown inFIG.4, the expression aλ may represent the value of the distance418, where a is a positive number representing the spacing factor for Tx antenna elements in each column and represents a wavelength. As further shown inFIG.4, the expression bλ may represent the value of the distance420, where b is a positive number representing the spacing factor for Tx antenna elements in each row.

The size of the Tx antenna array400may be expressed in terms of the number of antenna elements NT1414in each column of the Tx antenna array400and the number of antenna elements NT2416in each row of the Tx antenna array400. Accordingly, the size of the Tx antenna array400may be expressed as NT1×NT2. In the example ofFIG.4, since the Tx antenna array400includes three Tx antenna elements in each column (e.g., NT1=3) and four Tx antenna elements in each row (e.g., NT2=4), the size of the Tx antenna array400may be described as a three by four antenna array including 12 Tx antenna elements (e.g., 3×4=12 Tx antenna elements).

The Rx antenna array450includes a set of Rx antenna elements, such as Rx antenna elements452,454,456,458,460,462. In some examples, each of the Rx antenna elements in the Rx antenna array450may be approximately equal in size and may have a circular shape, such as the Rx antenna element452with diameter453. The Rx antenna elements in each column (e.g., Rx antenna elements452,454,456) of the Tx antenna array400may have uniform spacing and may be spaced apart by a center-to-center distance468(also referred to as inter-antenna element spacing468). The Rx antenna elements in each row (e.g., Rx antenna elements452,458,460,462) of the Rx antenna array450may have uniform spacing and may be spaced apart by a center-to-center distance470(also referred to as inter-antenna element spacing470). As shown inFIG.4, the expression cλ may represent the value of the distance468, where c is a positive number representing the spacing factor for Rx antenna elements in each column and λ represents a wavelength. As further shown inFIG.4, the expression dλ may represent the value of the distance470, where d is a positive number representing the spacing factor for Rx antenna elements in each row.

The size of the Rx antenna array450may be expressed in terms of the number of antenna elements NR1464in each column of the Rx antenna array450and the number of antenna elements NR2466in each row of the Rx antenna array450. Accordingly, the size of the Rx antenna array450may be expressed as NR1×NR2. In the example ofFIG.4, since the Rx antenna array450includes three Rx antenna elements in each column (e.g., NR1=3) and four Rx antenna elements in each row (e.g., NR2=4), the size of the Rx antenna array450may be described as a three by four antenna array including 12 Rx antenna elements (e.g., 3×4=12 Rx antenna elements).

In some examples, separate Tx and Rx antenna arrays (or antenna arrays with non-co-located Tx and Rx antenna elements) may have different array sizes for different frequencies. For example, some RF components in a Tx antenna array may consume more power, may occupy more area (e.g., may have a larger footprint), and/or may be more costly as compared to RF components in an Rx antenna array. This may be the case, for example, when a Tx antenna array is configured to operate with a power amplifier (PA) and the Rx antenna array is configured to operate with a low noise amplifier (LNA). In one example, the size (e.g., NT1×NT2) of the Tx antenna array400may be different from the size (e.g., NR1×NR2) of the Rx antenna array450.

In some examples, separate Tx and Rx antenna arrays (or antenna arrays with non-co-located Tx and Rx antenna elements) may have different inter-antenna element spacings in the vertical direction490(e.g., different spacing for Tx and Rx antenna elements along a column in an antenna array) and in the horizontal direction492(e.g., different spacing for Tx and Rx antenna elements along a row in an antenna array). In one example, and as previously described, the Tx antenna array400may have a size NT1×NT2, an inter-antenna element spacing aλ for Tx antenna elements along each column, and an inter-antenna element spacing bλ for Tx antenna elements along each row. In this example, the value of the spacing factor a may be different from the value of the spacing factor b. In another example, and as previously described, the Rx antenna array450may have a size NR1×NR2, an inter-antenna element spacing cλ for Rx antenna elements along each column, and an inter-antenna element spacing dλ for Rx antenna elements along each row. In this example, the value of the spacing factor c may be different from the value of the spacing factor d.

FIG.5illustrates an antenna500including an example implementation of separate Tx and Rx antenna arrays.FIG.5includes a Tx antenna array including a set of Tx antenna elements, such as Tx antenna elements502,504,506, and an Rx antenna array including a set of Rx antenna elements, such as Rx antenna elements508,510,512. In some examples, each of the Tx antenna elements may be approximately equal in size and may have a square shape, such as the Tx antenna element506with side dimension503. The Tx antenna elements in each column (e.g., Tx antenna elements502,504) may have uniform spacing and may be spaced apart by a center-to-center distance522(also referred to as inter-antenna element spacing522). The Tx antenna elements in each row (e.g., Tx antenna elements502,506) may have uniform spacing and may be spaced apart by a center-to-center distance524(also referred to as inter-antenna element spacing524). As shown inFIG.5, the expression aλ may represent the value of the distance522, where a is a positive number representing the spacing factor for Tx antenna elements in each column and λ represents a wavelength. As further shown inFIG.5, the expression bλ may represent the value of the distance524, where b is a positive number representing the spacing factor for Tx antenna elements in each row.

The size of the Tx antenna array may be expressed in terms of the number of antenna elements NT1514in each column of the Tx antenna array and the number of antenna elements NT2516in each row of the Tx antenna array. Accordingly, the size of the Tx antenna array may be expressed as NT1×NT2. In the example ofFIG.5, since the Tx antenna array includes four Tx antenna elements in each column (e.g., NT1=4) and eight Tx antenna elements in each row (e.g., NT2=8), the size of the Tx antenna array may be described as a four by eight antenna array including 32 Tx antenna elements (e.g., 4×8=32 Tx antenna elements).

The Rx antenna array includes a set of Rx antenna elements, such as Rx antenna elements508,510,512. In some examples, each of the Rx antenna elements in the Rx antenna array may be approximately equal in size and may have a circular shape, such as the Rx antenna element510with diameter553. The Rx antenna elements in each column (e.g., Rx antenna elements508,510) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance526(also referred to as inter-antenna element spacing526). The Rx antenna elements in each row (e.g., Rx antenna elements508,512) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance528(also referred to as inter-antenna element spacing528). As shown inFIG.5, the expression cλ may represent the value of the distance526, where c is a positive number representing the spacing factor for Rx antenna elements in each column and λ represents a wavelength. As further shown inFIG.5, the expression dλ may represent the value of the distance528, where d is a positive number representing the spacing factor for Rx antenna elements in each row.

The size of the Rx antenna array may be expressed in terms of the number of antenna elements NR1518in each column of the Rx antenna array and the number of antenna elements NR2520in each row of the Rx antenna array. Accordingly, the size of the Rx antenna array may be expressed as NR1×NR2. In the example ofFIG.5, since the Rx antenna array includes four Rx antenna elements in each column (e.g., NR1=4) and eight Rx antenna elements in each row (e.g., NR2=8), the size of the Rx antenna array may be described as a four by eight antenna array including 32 Rx antenna elements (e.g., 4×8=32 Rx antenna elements).

In the example ofFIG.5, the values of a, b, c, and d may be set to 0.5, such that each of the distances522,524,526,528is expressed as 0.5λ. InFIG.5, the Tx antenna array is offset from the Rx antenna array in the vertical direction590by a first offset distance (Δ1)530, and may be offset from the Rx antenna array in the horizontal direction592by a second offset distance (Δ2)532. In the example ofFIG.5, if the distances522,524,526,528are set to 0.5λ, then Δ1=Δ2=0.25.

FIG.6illustrates an antenna600including an example implementation of separate Tx and Rx antenna arrays.FIG.6includes a Tx antenna array including a set of Tx antenna elements, such as Tx antenna elements602,604,606, and an Rx antenna array including a set of Rx antenna elements, such as Rx antenna elements608,610,612. In some examples, each of the Tx antenna elements may be approximately equal in size and may have a square shape, such as the Tx antenna element602with side dimension603. The Tx antenna elements in each column (e.g., Tx antenna elements602,604) may have uniform spacing and may be spaced apart by a center-to-center distance622(also referred to as inter-antenna element spacing622). The Tx antenna elements in each row (e.g., Tx antenna elements602,606) may have uniform spacing and may be spaced apart by a center-to-center distance624(also referred to as inter-antenna element spacing624). As shown inFIG.6, the expression aλ may represent the value of the distance622, where a is a positive number representing the spacing factor for Tx antenna elements in each column and λ represents a wavelength. As further shown inFIG.6, the expression bλ may represent the value of the distance624, where b is a positive number representing the spacing factor for Tx antenna elements in each row.

The size of the Tx antenna array may be expressed in terms of the number of antenna elements NT1614in each column of the Tx antenna array and the number of antenna elements NT2616in each row of the Tx antenna array. Accordingly, the size of the Tx antenna array may be expressed as NT1×NT2. In the example ofFIG.6, since the Tx antenna array includes four Tx antenna elements in each column (e.g., NT1=4) and eight Tx antenna elements in each row (e.g., NT2=8), the size of the Tx antenna array may be described as a four by eight antenna array including 32 Tx antenna elements (e.g., 4×8=32 Tx antenna elements).

The Rx antenna array includes a set of Rx antenna elements, such as Rx antenna elements608,610,612. In some examples, each of the Rx antenna elements in the Rx antenna array may be approximately equal in size and may have a circular shape, such as the Rx antenna element610with diameter653. The Rx antenna elements in each column (e.g., Rx antenna elements608,610) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance626(also referred to as inter-antenna element spacing626). The Rx antenna elements in each row (e.g., Rx antenna elements608,612) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance628(also referred to as inter-antenna element spacing628). As shown inFIG.6, the expression cλ may represent the value of the distance626, where c is a positive number representing the spacing factor for Rx antenna elements in each column and represents a wavelength. As further shown inFIG.6, the expression dλ may represent the value of the distance628, where d is a positive number representing the spacing factor for Rx antenna elements in each row.

The size of the Rx antenna array may be expressed in terms of the number of antenna elements NR1618in each column of the Rx antenna array and the number of antenna elements NR2620in each row of the Rx antenna array. Accordingly, the size of the Rx antenna array may be expressed as NR1×NR2. In the example ofFIG.6, since the Rx antenna array includes four Rx antenna elements in each column (e.g., NR1=4) and eight Rx antenna elements in each row (e.g., NR2=8), the size of the Rx antenna array may be described as a four by eight antenna array including 32 Rx antenna elements (e.g., 4×8=32 Rx antenna elements).

In the example ofFIG.6, the values of a, b, c, and d may be set to 0.5, such that each of the distances622,624,626,628is expressed as 0.5λ. InFIG.6, the Tx antenna array is offset from the Rx antenna array in the vertical direction690by a first offset distance (Δ1)630. In the example ofFIG.6, if the distances622is set to 0.5λ, then Δ1=(4)0.5λ=2λ. It should be noted that the Tx antenna array is not offset from the Rx antenna array in the horizontal direction692.

FIG.7illustrates an antenna700including an example implementation of separate Tx and Rx antenna arrays.FIG.7includes a Tx antenna array including a set of Tx antenna elements, such as Tx antenna elements702,704,706, and an Rx antenna array including a set of Rx antenna elements, such as Rx antenna elements708,710,712. In some examples, each of the Tx antenna elements may be approximately equal in size and may have a square shape, such as the Tx antenna element706with side dimension703. The Tx antenna elements in each column (e.g., Tx antenna elements702,704) may have uniform spacing and may be spaced apart by a center-to-center distance722(also referred to as inter-antenna element spacing722). The Tx antenna elements in each row (e.g., Tx antenna elements702,706) may have uniform spacing and may be spaced apart by a center-to-center distance724(also referred to as inter-antenna element spacing724). As shown inFIG.7, the expression aλ may represent the value of the distance722, where a is a positive number representing the spacing factor for Tx antenna elements in each column and λ represents a wavelength. As further shown inFIG.7, the expression bλ may represent the value of the distance724, where b is a positive number representing the spacing factor for Tx antenna elements in each row.

The size of the Tx antenna array may be expressed in terms of the number of antenna elements NT1714in each column of the Tx antenna array and the number of antenna elements NT2716in each row of the Tx antenna array. Accordingly, the size of the Tx antenna array may be expressed as NT1×NT2. In the example ofFIG.7, since the Tx antenna array includes four Tx antenna elements in each column (e.g., NT1=4) and eight Tx antenna elements in each row (e.g., NT2=8), the size of the Tx antenna array may be described as a four by eight antenna array including 32 Tx antenna elements (e.g., 4×8=32 Tx antenna elements).

The Rx antenna array includes a set of Rx antenna elements, such as Rx antenna elements708,710,712. In some examples, each of the Rx antenna elements in the Rx antenna array may be approximately equal in size and may have a circular shape, such as the Rx antenna element712with diameter753. The Rx antenna elements in each column (e.g., Rx antenna elements708,710) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance726(also referred to as inter-antenna element spacing726). The Rx antenna elements in each row (e.g., Rx antenna elements708,712) of the Rx antenna array may have uniform spacing and may be spaced apart by a center-to-center distance728(also referred to as inter-antenna element spacing728). As shown inFIG.7, the expression cλ may represent the value of the distance726, where c is a positive number representing the spacing factor for Rx antenna elements in each column and represents a wavelength. As further shown inFIG.7, the expression dλ may represent the value of the distance728, where d is a positive number representing the spacing factor for Rx antenna elements in each row.

The size of the Rx antenna array may be expressed in terms of the number of antenna elements NR1718in each column of the Rx antenna array and the number of antenna elements NR2720in each row of the Rx antenna array. Accordingly, the size of the Rx antenna array may be expressed as NR1×NR2. In the example ofFIG.7, since the Rx antenna array includes four Rx antenna elements in each column (e.g., NR1=4) and eight Rx antenna elements in each row (e.g., NR2=8), the size of the Rx antenna array may be described as a four by eight antenna array including 32 Rx antenna elements (e.g., 4×8=32 Rx antenna elements).

In the example ofFIG.7, the values of a, b, c, and d may be set to 0.5, such that each of the distances722,724,726,728is expressed as 0.5λ. InFIG.7, the Tx antenna array is offset from the Rx antenna array in the horizontal direction792by an offset distance (Δ1)730. In the example ofFIG.7, if the distance724is set to 0.5λ, then Δ1=(8)0.5=4λ. It should be noted that the Tx antenna array is not offset from the Rx antenna array in the vertical direction790.

FIG.8illustrates a transceiver800including a transmit (Tx) antenna array802and a receive (Rx) antenna array852in accordance with various aspects of the disclosure. The Tx antenna array802may include a surface803and a number of Tx antenna elements. In one example, the Tx antenna array802may be the Tx antenna array400previously described with reference toFIG.4. The Rx antenna array852may include a surface853and a number of Rx antenna elements. In one example, the Rx antenna array852may be the Rx antenna array450previously described with reference toFIG.4.

As shown inFIG.8, the Tx antenna array802may have a height806and a width808. The height806may be expressed as aλ·NT1, where a is a positive number representing the spacing factor for Tx antenna elements in each column, λ represents a wavelength, and NT1is the number of Tx antenna elements in each column. The width808may be expressed as bλ·NT2, where b is a positive number representing the spacing factor for Tx antenna elements in each row, λ represents a wavelength, and NT2is the number of Tx antenna elements in each row. The center of the Tx antenna array802is indicated at the center point804.

The Rx antenna array852may have a height856and a width858. The height856may be expressed as cλ·NR1, where c is a positive number representing the spacing factor for Rx antenna elements in each column, λ represents a wavelength, and NR1is the number of Rx antenna elements in each column. The width858may be expressed as dλ·NR2, where d is a positive number representing the spacing factor for Rx antenna elements in each row, λ represents a wavelength, and NR2is the number of Rx antenna elements in each row. The center of the Rx antenna array852is indicated at the center point854.

As shown inFIG.8, the Rx antenna array852is offset from the Tx antenna array802in the vertical direction890by a first offset distance (Δ1)810, and the Rx antenna array852is offset from the Tx antenna array802in the horizontal direction892by a second offset distance (Δ2)860. In some examples, the first offset distance (Δ1)810may be the vertical distance between a first Tx antenna element in a first row and a first column in the Tx antenna array802and a first Rx antenna element in a first row and a first column in the Rx antenna array852. In some examples, the second offset distance (Δ2)860may be the horizontal distance between the first Tx antenna element in the first row and the first column in the Tx antenna array802and the first Rx antenna element in the first row and the first column in the Rx antenna array852.

FIG.9illustrates a transmit beam902formed at the Tx antenna array802and a receive beam912formed at the Rx antenna array852. In some examples, the transceiver800including the Tx antenna array802and the Rx antenna array852may be implemented in a wireless communication device900. In some examples, the wireless communication device900may be a base station. For example, the wireless communication device900may form the transmit beam902to transmit downlink (DL) signals to the UE950, and may form the receive beam912to receive uplink (UL) signals from the UE950.

In the example scenario ofFIG.9, a wireless communication channel between the wireless communication device900and the UE950may include an object906. The term wireless communication channel (also more simply referred to as a channel) as used herein may refer to a path over which energy is steered between wireless communication devices. For example, the object906may be a structure (e.g., a building), a vehicle, a natural object (e.g., a tree), or any other type of object capable of reflecting, diffracting, or scattering wireless communication signals.

In some scenarios, the object906(or a portion of the object906) may be referred to as a cluster. The term “cluster” as used herein is defined as an object in the wireless communication environment between first and second wireless communication devices which allows steering of energy from one wireless communication device to another. In some examples, a cluster at millimeter wave frequencies may be a reflector (e.g., a glass or metallic object), a diffractor (e.g., a corner of a building or a sharp object) or a diffuse scatterer (e.g., an object having a dimensionality larger than the carrier wavelength allowing a scattering of the transmitted energy in non-distinct directions).

As shown inFIG.9, the wireless communication device900may determine that the cluster907in the wireless communication channel provides the best signal strength and may form the transmit beam902in a direction toward the cluster907. InFIG.9, for example, the direction of the transmit beam902toward the cluster907is indicated with the signal transmission path904. The wireless communication device900may assume channel reciprocity and may form the receive beam912toward the cluster907. InFIG.9, for example, the direction of the receive beam912toward the cluster907is indicated with the signal reception path914. The UE950may form a beam908toward the cluster907for reception of signal transmissions. The UE950may assume channel reciprocity and may use the beam908for signal transmissions toward the cluster907. InFIG.9, for example, the direction of the beam908toward the cluster907is indicated with the signal reception path910and the signal transmission path916.

The separation of the Tx antenna array802from the Rx antenna array852may cause the direction of the transmit beam902and the direction of the receive beam912to form an angle θ918at the cluster907. In some examples, the angle θ918may represent the difference between the direction of the transmit beam902and the direction of the receive beam912. Therefore, larger values of a distance D920between the Tx antenna array802and the Rx antenna array852(e.g., larger distances between the center point804of the Tx antenna array802and the center point854of the Rx antenna array852) may result in larger values of the angle θ918.

In some scenarios, the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912may increase to a point where beam correspondence may no longer be achieved. In other words, a beam correspondence failure may occur at the wireless communication device900. Therefore, in these scenarios, the wireless communication device900may no longer assume channel reciprocity and may need to decouple the direction of the transmit beam902from the direction of the receive beam912. As a result, the wireless communication device900may need to steer the directions of the transmit and receive beams902,912independently in different directions.

Beam correspondence failures may occur dynamically and may depend on one or more factors. In some examples, an occurrence of a beam correspondence failure may depend on a size of a transmit antenna array or a receive antenna array implemented by a wireless communication device, a spacing between antenna elements in the transmit antenna array or the receive antenna array, a distance from the transmit antenna array or receive antenna array to a cluster or reflector in the wireless communication channel, a beamwidth of a transmit beam (e.g., formed at the transmit antenna array) in elevation and azimuth, and/or a beamwidth of a receive beam (e.g., formed at the receive antenna array) in elevation and azimuth.

In some examples, a beam correspondence failure may occur dynamically at a wireless communication device when switching between antenna arrays of different sizes (e.g., when operating at frequency bands within FR4 or greater). In some examples, the spacing between antenna elements in a transmit antenna array or the spacing between antenna elements in a transmit antenna array may be a center-to-center distance that is within the range 0.3λ to 0.8λ, where λ represents a wavelength.

In some examples, the distance from the transmit antenna array or receive antenna array to a cluster or reflector in the wireless communication channel may change dynamically due to changes in the channel environment. For example, an automobile may be acting as a cluster or reflector in the wireless communication channel and the distance from the transmit antenna array or receive antenna array to the automobile may change as the automobile moves. In some examples, the beamwidth of the transmit beam and/or the beamwidth of the receive beam may change dynamically based on the set of beam weights applied at the transmit antenna array or the receive antenna array.

When a beam correspondence failure occurs at a wireless communication device, the wireless communication device may need to perform a beam training procedure for the transmit beam and/or a beam training procedure for the receive beam.

FIG.10illustrates a top view of an antenna array1002in a wireless communication device1000. The antenna array1002may include a Tx antenna array and an Rx antenna array. With reference toFIG.10, the wireless communication device1000may perform separate beam training procedures to determine different transmit and receive beams at the antenna array1002. For example, the wireless communication device1000may form a group of transmit beams1004and may select the best transmit beam1014as the downlink (DL) serving beam (e.g., for transmitting downlink signals to a second wireless communication device, such as a UE) based on beam strength. The wireless communication device1000may proceed to form groups of receive beams, such as a first group of receive beams1006, a second group of receive beams1008, a third group of receive beams1010, and a fourth group of receive beams1012.

The wireless communication device1000may select a set of receive beams1016,1018,1020,1022closest to the DL serving beam1014from the groups of receive beams1006,1008,1010,1012, where the set of receive beams1016,1018,1020,1022serve as uplink (UL) candidate beams. The wireless communication device1000may determine a best receive beam from the set of receive beams1016,1018,1020,1022based on beam strength (e.g., an RSRP measurement) and may select the best receive beam as the receive beam for reception of UL signals from the second wireless communication device.

Since beam correspondence failures may occur dynamically at the wireless communication device1000, the wireless communication device1000may not be aware as to when beam correspondence exists or has failed at any given time. Therefore, in some scenarios, the wireless communication device1000may be using a transmit beam as a receive beam when beam correspondence no longer exists and may experience a loss in performance. In other scenarios, the wireless communication device1000may need to perform a receive beam training procedure every time a transmit beam is changed or switched. This may introduce a significant overhead in the network in situations where transmit beams are frequently changed or switched.

FIG.11illustrates the Tx and Rx antenna arrays802,852and a distance m between the center of the Tx antenna array802(e.g., at center point804) and the center of the Rx antenna array852(e.g., at center point854). As shown inFIG.11, the distance m may be determined by forming a right triangle including sides1102,1104, and1100and solving for the length of the side1100(e.g., using the Pythagorean theorem). For example, the side1102may have a length y, which may be determined using the following equation (1):

y≈❘"\[LeftBracketingBar]"Δ1-a⁢λ·NT12+c⁢λ·NR12❘"\[RightBracketingBar]"(1)
where y represents the length of side1102, Δ1represents the first offset distance810, a is a positive number representing the spacing factor for Tx antenna elements in each column of the Tx antenna array802, λ represents a wavelength, NT1represents the number of Tx antenna elements in each column of the Tx antenna array802, c is a positive number representing the spacing factor for Rx antenna elements in each column of the Rx antenna array852, and NR1represents the number of Rx antenna elements in each column of the Rx antenna array852.

For example, with reference toFIG.11, the expression (aλ·T1)/2 in equation (1) may represent the length1106, the expression (cλ·NR1)/2 may represent the length1110, and the difference between Δ1and the expression (aλ·T1)/2 may represent the length1108. It should be noted that the sum of the lengths1108and1110is approximately equal to the length y.

For example, side1104may have a length x, which may be determined using the following equation (2):

x≈❘"\[LeftBracketingBar]"Δ2-b⁢λ·NT22+d⁢λ·NR22❘"\[RightBracketingBar]"(2)
where x represents the length of side1104, Δ2represents the second offset distance860, b is a positive number representing the spacing factor for Tx antenna elements in each row, λ represents a wavelength, NT2represents the number of antenna elements in each row of the Tx antenna array802, d is a positive number representing the spacing factor for Rx antenna elements in each row of the Rx antenna array852, and NR2represents the number of antenna elements in each row of the Rx antenna array852.

For example, with reference toFIG.11, the expression (bλ·NT2)/2 in equation (2) may represent the length1112, the expression (dλ·NR2)/2 may represent the length1114, and the difference between Δ2and the expression (bλ·NT2)/2 may represent the length1116. It should be noted that the difference between the lengths1114and1116is approximately equal to the length x.

Therefore, the length of the side1100(e.g., the distance m) may be determined using the following equation (3):
m=√{square root over (x2+y2)}  (3)
where y represents the length of side1102as determined using equation (1), and x represents the length of side1104as determined using equation (2). Therefore, the distance between the points804and854may be approximately equal to the value of m as determined using equation (3).

FIG.12illustrates a wireless communication device configured to monitor the difference between the first direction of the transmit beam902formed at the Tx antenna array802and the second direction of the receive beam912formed at the Rx antenna array852. As shown inFIG.12, the direction of the transmit beam902toward the cluster907is indicated with the signal transmission path904, and the direction of the receive beam912toward the cluster907is indicated with the signal transmission path914. Due to the separation of the Tx and Rx antenna arrays802,852, the direction of the transmit beam902may be different from the direction of the receive beam912. The difference between the directions of the transmit and receive beams902,912may be represented by the angle θ918.

In some examples, the wireless communication device900may determine the value of the angle θ918based on a size of the Tx antenna array802(e.g., NT1×NT2), a size of the Rx antenna array852(e.g., NR1×NR2), the geometry (e.g., shape) of the Tx antenna array802, the geometry (e.g., shape) of the Rx antenna array852, an arrangement of transmit antenna elements (e.g., rows, columns) in the Tx antenna array802, an arrangement of receive antenna elements (e.g., rows, columns) in the Rx antenna array852, a set of beam weights associated with the transmit beam902, a set of beam weights associated with the receive beam912, a distance between the Tx antenna array802and the Rx antenna array852(e.g., the distance m between the center of the Tx antenna array802(e.g., at center point804) and the center of the Rx antenna array852(e.g., at center point854)), and/or a distance from the Tx antenna array802or the Rx antenna array852to a cluster (e.g., the cluster907) or a reflector (e.g., the object906) in a channel over which energy is steered between the wireless communication device900and another wireless communication device (e.g., the UE950).

In some aspects of the disclosure, the wireless communication device900may determine the difference between the directions of the transmit and receive beams902,912(e.g., the angle θ918) using equation (4):

θ≈180π·mD(4)
where θ (e.g., the angle θ918) represents the difference between the direction of the transmit beam902and the direction of the receive beam912, m represents the center-to-center distance between the Tx and Rx antenna arrays802,852, D represents the distance from the Tx antenna array802or the Rx antenna array852to a cluster (e.g., cluster907) or reflector (e.g., object906) in the wireless communication channel, and 180/π is a conversion factor for converting radians to degrees. In some examples, the value of D may be sufficiently large so that far field conditions hold.

It should be noted that the distance m, the distance from the Tx antenna array802to the cluster907(e.g., the distance from the center point804to the cluster907), and the distance from the Rx antenna array852to the cluster907(e.g., the distance from the center point854to the cluster907) form a triangle where the angle θ918is opposite to the distance m. Therefore, the wireless communication device900may apply equation (4) to determine the angle θ918of this triangle.

Since the distance m may be expressed as √{square root over (x2+y2)} as described with reference to equation (3), equation (4) may be rewritten to replace m with the expression √{square root over (x2+y2)} as shown in the following equation (5):

θ≈180π·x2+y2D(5)
where y represents the length of side1102as determined using equation (1), and x represents the length of side1104as determined using equation (2).

In some scenarios, if the wireless communication device900has a line of sight (LOS) to a different wireless communication device (e.g., a UE, CPE), the distance from the Tx antenna array802or the Rx antenna array852to the cluster or reflector in the wireless communication channel may be the distance from the Tx antenna array802or the Rx antenna array852to the different wireless communication device. In these scenarios, the wireless communication device900may estimate the distance from the Tx antenna array802or the Rx antenna array852to the different wireless communication device (e.g., the UE950).

In some examples, the wireless communication device900may estimate the distance from the wireless communication device900to the different wireless communication device (e.g., the UE950) based on a location of the different wireless communication device. For example, the wireless communication device900may determine the location of the different wireless communication device (e.g., the UE950) based on a positioning algorithm that indicates the location of the different wireless communication device (e.g., the UE950).

In some examples, the wireless communication device900may receive one or more path loss estimates from the different wireless communication device (e.g., UE950). The wireless communication device900may estimate the distance from the wireless communication device900to the different wireless communication device (e.g., the UE950) based on the one or more path loss estimates.

In some scenarios, if the wireless communication device900does not have a line of sight (LOS) to a different wireless communication device (e.g., a UE, CPE), the distance from the Tx antenna array802or the Rx antenna array852to the cluster or reflector in the wireless communication channel may be different from the distance from the Tx antenna array802or the Rx antenna array852to the different wireless communication device (e.g., a UE, CPE). In these scenarios, the wireless communication device900may determine the distance from the Tx antenna array802or the Rx antenna array852to the cluster or reflector in the wireless communication channel based on a location of an object (e.g., the object906) capable of reflecting, diffracting or scattering wireless communication signals.

In some examples, the wireless communication device900may determine the distance to the cluster or reflector based on the location of the wireless communication device900and information about the static environment around the wireless communication device900(e.g., installation information indicating locations of buildings, fixtures, or other structures). In some examples, the wireless communication device900may use path loss estimates from the different wireless communication device (e.g., a UE, CPE) in combination with the location of the wireless communication device900and information about the static environment around the wireless communication device900to determine the distance between the wireless communication device900and the cluster or reflector

In some examples, the wireless communication device900may determine the distance from the Tx antenna array802or the Rx antenna array852to the cluster or reflector in the wireless communication channel based on one or more path loss estimates and/or other information received from the different wireless communication device (e.g., a UE, CPE). For example, the wireless communication device900may receive one or more path loss estimates from the different wireless communication device (e.g., the UE950) and/or information indicating a location of an object (e.g., the object906) capable of reflecting, diffracting, or scattering wireless communication signals. The wireless communication device900may determine the distance from the transmit antenna array802or the receive antenna array852to the cluster or reflector based on the one or more path loss estimates and/or the location of the object capable of reflecting or diffracting or scattering wireless communication signals.

In indoor settings, the wireless communication device900may use ray tracing and map-based information, which may indicate the location of potential dominant clusters or reflectors in the wireless communication channel. For example, the wireless communication device900may determine the location of potential dominant clusters or reflectors through which a directional link has been established (e.g., glass, metallic object, etc.) in the wireless communication channel using ray tracing and the map-based information. The wireless communication device900may use the location of a potential dominant cluster or reflector to determine the distance from the transmit antenna array802or the receive antenna array852to the dominant cluster or reflector.

In some examples, the wireless communication device900may provide additional signaling to the different wireless communication device (e.g., UE950) to determine the cluster or reflector.

In some examples, if the different wireless communication device (e.g., UE950) has the ability to obtain information indicating the distance to the cluster or reflector and/or the location of the cluster or reflector, the different wireless communication device (e.g., UE950) may report this information to the wireless communication device900. In some examples, the wireless communication device900may combine the reported information indicating the distance to the cluster or reflector with one or more path loss estimates from the different wireless communication device (e.g., UE950) to determine the distance between the transmit antenna array802or the receive antenna array852to the cluster or reflector. In some examples, the information may include sensor data, such as radar data, light detection and ranging (LIDAR) data, etc.

Determination of a Beam Correspondence Failure

The wireless communication device900may determine that a beam correspondence failure has occurred when the difference between the directions of the transmit and receive beams902,912(e.g., the angle θ918) is greater than or equal to a beam correspondence threshold. In some aspects of the disclosure, the beam correspondence threshold may be a value (e.g., an angle in degrees) based on a beamwidth of the transmit beam902or a beamwidth of the receive beam912.

For example,FIG.13illustrates the gain of the Tx antenna array802with respect to the direction (e.g., angle) of the transmit beam902. As shown in the example ofFIG.13, the Tx antenna array802steers the transmit beam902towards a peak direction θ0to achieve a peak gain value G. In some examples, the peak gain value G may represent a number in units of decibels (dB). InFIG.13, the curve1302represents the shape (e.g., beam pattern) of the transmit beam902, and the arrow1304indicates the peak direction θ0.

In some examples, the beam correspondence threshold may be a beamwidth φ1320. For example, the beamwidth φ1320may represent an angle in units of degrees. In some aspects of the disclosure, and as described in detail below, the wireless communication device900may determine the beam correspondence threshold (e.g., the beamwidth φ1320) based on a threshold gain value K. In some examples, the threshold gain value K may represent a number in units of decibels (dB).

In some aspects of the disclosure, the wireless communication device900may determine the threshold gain value K based on the peak gain value G and a threshold gain control value S (e.g., the threshold gain control value S1306inFIG.13). The threshold gain control value S may represent a number in units of decibels (dB). In some examples, the wireless communication device900may use the threshold gain control value S to determine an acceptable lower bound array gain (e.g., threshold gain value K) with respect to the peak gain value G. In some examples, the wireless communication device900may set the threshold gain control value S to 3 dB. In other examples, the wireless communication device900may set the threshold gain control value S to a value less than 3 dB or greater than 3 dB. In some aspects of the disclosure, the wireless communication device900may configure the threshold gain control value S in coordination with a different wireless communication device (e.g., UE950, a CPE) in the network.

In some examples, to determine the beam correspondence threshold (e.g., the beamwidth φ1320), the wireless communication device900may first determine the threshold gain value K. For example, the wireless communication device900may determine the threshold gain value K by determining the difference between the peak gain value G and the threshold gain control value S (e.g., K=G−S). The wireless communication device900may locate the points where the beam pattern (e.g., the curve1302) of the transmit beam902intersects the threshold gain value K (e.g., at points1308,1310). The beamwidth φ1320may be defined between these points (e.g., the points1308,1310).

It should be noted that the threshold gain value K may represent an acceptable lower bound array gain for the Tx antenna array802for purposes of determining beam correspondence. For example, in one scenario, if the direction of the transmit beam902drifts away from the peak direction θ0indicated with the arrow1304, and the gain of the Tx antenna array802consequently drops to a value between the peak gain value G and the threshold gain value K, the wireless communication device900may determine that the gain of the Tx antenna array802is acceptable for beam correspondence. In another scenario, if the gain of the Tx antenna array802drops below the threshold gain value K, the wireless communication device900may determine that the gain of the Tx antenna array802is not acceptable for beam correspondence.

It should further be noted that the size of the threshold gain control value S may control the range of acceptable gain values for the Tx antenna array802with respect to the peak gain value G for purposes of determining beam correspondence. In one example, if the threshold gain control value S is set to 3 dB, a gain of the Tx antenna array802falling between G and G−3 dB (e.g., K=G−3 dB) may be acceptable for purposes of determining beam correspondence. In another example, if the threshold gain control value S is set to 6 dB, a gain of the Tx antenna array802falling between G and G−6 dB (e.g., K=G−6 dB) may be acceptable for purposes of determining beam correspondence.

Referring back toFIG.12, the wireless communication device900may compare the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912to a beam correspondence threshold. As previously described, the beam correspondence threshold may be the beamwidth φ (e.g., the beamwidth φ1320) corresponding to the signal strength threshold (e.g., the threshold gain value K). If the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is greater than or equal to the beam correspondence threshold (e.g., if θ≥φ), the wireless communication device900may determine that a beam correspondence failure has occurred.

In some aspects of the disclosure, the wireless communication device900may periodically determine the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912and may compare the difference to the beam correspondence threshold to enable dynamic detection of any beam correspondence failures.

For example, if the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is greater than or equal to the beam correspondence threshold (e.g., if θ≥φ), the wireless communication device900may determine that the gain of the receive beam912is at least S dB greater than the gain of the transmit beam902. This is expressed in the following condition (6):
|GainUL−GainDL|≥S(6)
where the term GainULrepresents the gain of the receive beam912, the term GainDLrepresents the gain of the transmit beam902, and S represents the threshold gain control value S (e.g., the threshold gain control value S1306inFIG.13). In some examples, the terms GainUL, GainDL, and S may be in units of decibels (dB). The wireless communication device900may consider the previously described condition (6) as providing an unacceptable level of beam correspondence and may determine that a beam correspondence failure has occurred.

If the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is less than the beam correspondence threshold (e.g., if θ<φ), the wireless communication device900may determine that a beam correspondence failure has not occurred. For example, if the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is less than the beam correspondence threshold (e.g., if θ<φ), the wireless communication device900may determine that the receive beam912has a gain that is within S dB of the transmit beam902. This is expressed in the following condition (7):
|GainUL−GainDL|<S(7)
where the terms the terms GainUL, GainDL, and S have been previously described with reference to condition (6). The wireless communication device900may consider the previously described condition (7) as providing an acceptable level of beam correspondence. Therefore, if the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is less than the beam correspondence threshold (e.g., if θ<φ), the wireless communication device900may determine that a beam correspondence failure has not occurred.

In some aspects of the disclosure, the wireless communication device900may transmit an indication of a beam correspondence failure to the UE950when the difference (e.g., the angle θ918) between the direction of the transmit beam902and the direction of the receive beam912is greater than or equal to the beam correspondence threshold. In some examples, the wireless communication device900may transmit a message to the UE950including a bit field for indicating a beam correspondence failure. For example, the wireless communication device900may set a bit in the bit field to a first value (e.g., ‘1’) if a beam correspondence failure has occurred, or may set the bit to a second value (e.g., ‘0’) if a beam correspondence failure has not occurred.

In some scenarios, the wireless communication device900may not be able to accurately determine the distance to the cluster or reflector in the wireless communication channel. In these scenarios, the wireless communication device900may determine whether a beam correspondence failure has occurred based on an estimate of the distance (also referred to as Dest) to the cluster or reflector in the wireless communication channel. In some examples, the estimate of the distance (Dest) may be a coarse estimate (e.g., within a range of ±25%) of the actual distance between the wireless communication device900and the cluster (e.g., the cluster907) or reflector (e.g., the object906).

For example, the wireless communication device900may estimate the distance from the transmit antenna array802or the receive antenna array852to a cluster or reflector in the wireless communication channel and may compare the estimated distance (Dest) to a distance threshold (also referred to as Dthreshold). For example, the distance threshold (Dthreshold) may be a number in units of meters.

If the estimated distance is less than or equal to the distance threshold (Dthreshold) (e.g., if Dest≤Dthreshold), the wireless communication device900may determine that a beam correspondence failure has occurred. In some aspects of the disclosure, the wireless communication device900may determine that a beam correspondence failure has occurred upon detection of the condition Dest≤Dthresholdand/or the condition θ≥φ. In some examples, the wireless communication device900may transmit an indication of a beam correspondence failure to a wireless communication device (e.g., the UE950) when the estimated distance (Dest) is less than or equal to the distance threshold (Dthreshold). In some examples, the wireless communication device900may transmit a message to the UE950including a bit field for indicating a beam correspondence failure as described herein. Therefore, if the wireless communication device900determines that the estimated distance (Dest) is too short (e.g., Dest≤Dthreshold), the wireless communication device900may infer that beam correspondence between the transmit beam902and the receive beam912cannot be achieved and may prepare for a beam refinement operation (e.g., an event triggered beam refinement operation) with respect to the UE950.

In some examples, the wireless communication device900may determine the value of the distance threshold (Dthreshold) based on the previously described signal strength threshold (e.g., the threshold gain value K), a beamwidth of the transmit beam902or the receive beam912, a size of the Tx antenna array802(e.g., NT1×NT2), a size of the Rx antenna array852(e.g., NR1×NR2), a spacing of transmit antenna elements in the Tx antenna array802, a spacing of receive antenna elements in the Rx antenna array852, and/or a beamwidth factor γ. The beamwidth of the transmit beam902or the receive beam912used for determination of the distance threshold (Dthreshold) may be set based on the previously described signal strength threshold (e.g., the threshold gain value K).

FIG.14illustrates a wireless communication device1400including a transceiver1402in accordance with various aspects of the disclosure. In some examples, the wireless communication device1400may be a base station. The transceiver1402includes a transmit (Tx) antenna array1404and a receive (Rx) antenna array1422in accordance with various aspects of the disclosure. The Tx antenna array1404may include a number of Tx antenna elements. In one example, the Tx antenna array1404may be the Tx antenna array400previously described with reference toFIG.4. The Rx antenna array1422may include a number of Rx antenna elements. In one example, the Rx antenna array1422may be the Rx antenna array450previously described with reference toFIG.4.

The Tx antenna array1404may have a height1408and a width1410. The height1408may be expressed as aλ·NT1, where a is a positive number representing the spacing factor for Tx antenna elements in each column, λ represents a wavelength, and NT1is the number of antenna elements in each column. The width1410may be expressed as bλ·NT2, where b is a positive number representing the spacing factor for Tx antenna elements in each row and NT2is the number of Tx antenna elements in each row. The center of the Tx antenna array1404is indicated at the center point1406.

The Rx antenna array1422may have a height1426and a width1428. The height1426may be expressed as cλ·NR1, where c is a positive number representing the spacing factor for Rx antenna elements in each column, λ represents a wavelength, and NR1is the number of Rx antenna elements in each column. The width1428may be expressed as dλ·NT2, where d is a positive number representing the spacing factor for Rx antenna elements in each row and NR2is the number of Rx antenna elements in each row. The center of the Rx antenna array1422is indicated at the center point1424.

In the example configuration of the transceiver1402shown inFIG.14, the Tx antenna array1404is situated adjacent to the Rx antenna array1422in the vertical direction1490. The distance m1470represents the distance between the center point1406of the Tx antenna array1404and the center point1424of the Rx antenna array1422.

FIG.14illustrates a transmit beam1412formed at the Tx antenna array1404and a receive beam1430formed at the Rx antenna array1422. For example, the wireless communication device1400may form the transmit beam1412to transmit downlink (DL) signals to the UE1450, and may form the receive beam1430to receive uplink (UL) signals from the UE1450.

The wireless communication device1400may determine that the cluster1407(e.g., at the object1416) in the wireless communication channel provides the best signal strength and may form the transmit beam1412in a direction toward the cluster1407. In some examples, the object1416may be the same as the object906described with reference toFIG.9.

InFIG.14, for example, the direction of the transmit beam1412toward the cluster1407is indicated with the signal transmission path1414. The wireless communication device1400may assume channel reciprocity and may form the receive beam1430toward the cluster1407. InFIG.14, for example, the direction of the receive beam1430toward the cluster1407is indicated with the signal reception path1432. The UE1450may form a beam1418toward the cluster1407for reception of signal transmissions. The UE1450may assume channel reciprocity and may use the beam1418for signal transmissions toward the cluster1407. InFIG.14, for example, the direction of the beam1418toward the cluster1407is indicated with the signal reception path1420and the signal transmission path1434.

The separation of the Tx antenna array1404from the Rx antenna array1422may cause the direction of the transmit beam1412and the direction of the receive beam1430to form an angle θ1436at the cluster1407. In some examples, the angle θ1436may represent the difference between the direction of the transmit beam1412and the direction of the receive beam1430.

In one example, the Tx antenna array1404may be the same size as the Rx antenna array1422and may have the same inter-antenna element spacing. Therefore, NT1may be equal to NR1, NT2may be equal to NR2, a may be equal to c, and b may be equal to d. In this example, the wireless communication device1400may form the transmit beam1412and the receive beam1430based on code-book based discrete Fourier transform (DFT) beams with progressive phase shifts. If the wireless communication device1400sets the threshold gain control value S to 3 dB, the beamwidth φ (also referred to as a 3 dB beamwidth) may be expressed as 100/N (or as γ·100/N when the beamwidth factor γ is applied), where N represents the antenna dimension of the Tx antenna array1404(e.g., the number of Tx antenna elements in each column). In some examples, the result of the expression 100/N or γ·100/N may be in units of degrees.

In some examples, the value of the beamwidth factor γ may be a number within the range of 1 and 2. In other examples, the value of the beamwidth factor γ may be a number that is greater than or equal to 1. In some aspects of the disclosure, the beamwidth factor γ may be applied to increase the 3 dB beamwidth (e.g., 100/N), thereby allowing a greater discrepancy between the directions of the transmit and receive beams for acceptable beam correspondence. For example, if the beamwidth factor γ is set to 1, a difference between the directions of the transmit and receive beams (e.g., the angle θ1436) where the receive beam achieves a gain value 3 dB below the gain value of the transmit beam (e.g., 3 dB·1=3 dB) may be considered acceptable beam correspondence. In another example, if the beamwidth factor γ is set to 1.5, a difference (e.g., the angle θ1436) between the directions of the transmit and receive beams where the receive beam achieves a gain value 4.5 dB below the gain value of the transmit beam (e.g., 3 dB·1.5=4.5 dB) may be considered acceptable beam correspondence.

Determination of the distance threshold (Dthreshold_1) for the configuration of the transceiver1402shown inFIG.14will now be described. For example, the wireless communication device1400may determine that a beam correspondence failure has occurred when the angle θ1436meets or exceeds the 3 dB bandwidth of the transmit beam1412or receive beam1430as shown with the following condition (8):

180π·mD≥γ·100N(8)
where the expression [(180/π)·(m/D)] represents the value of angle θ1436(e.g., as described with reference to equation (4)) and the expression γ·100/N represents the product of the beamwidth factor γ and the 3 dB bandwidth of the transmit beam1412or receive beam1430as previously described. Since the distance m1470may be expressed as aλ·NT1and the antenna dimension N is represented by NT1, the condition (8) above may be rewritten as shown in the following condition (9):

180π·a⁢λ·NT1D≥γ·100NT1.(9)

The above condition (9) may be solved for the distance D to obtain the following condition (10):

D≤1.8π·a⁢λ·NT12γ.(10)

Therefore, since the wireless communication device1400may determine that a beam correspondence failure has occurred when the distance (D) from the Tx antenna array1404or the Rx antenna array1422to the cluster1407(or the object1416) is less than or equal to the result of the expression [(1.8/π)·(aλ·NT12)/γ], the result of the expression [(1.8/π)·(aλ·NT12)/γ] may represent the value of the distance threshold (e.g., Dthreshold_1) for the example ofFIG.14.

FIG.15shows a set of curves illustrating example relationships between the antenna dimension NT1for the Tx antenna array1404and the distance threshold (e.g., Dthreshold_1) for the Tx antenna array1404when a is set to 0.7. For example, curve1502represents the relationship between the antenna dimension NT1and the distance threshold (e.g., Dthreshold_1) for the Tx antenna array1404when operating at a frequency of 30 GHz, curve1504represents the relationship between the antenna dimension NT1and the distance threshold (e.g., Dthreshold_1) for the Tx antenna array1404when operating at a frequency of 60 GHz, and curve1506represents the relationship between the antenna dimension NT1and the distance threshold (e.g., Dthreshold_1) for the Tx antenna array1404when operating at a frequency of 120 GHz. InFIG.15, it should be noted that for a given antenna dimension NT1, the distance threshold (e.g., Dthreshold_1) may be inversely proportional to the frequency of the Tx antenna array1404. For example, when the antenna dimension NT1is 48, the distance threshold (e.g., Dthreshold_1) decreases as the operating frequency increases.

FIG.16illustrates a wireless communication device1600including a transceiver1602in accordance with various aspects of the disclosure. In some examples, the wireless communication device1600may be a base station. It should be noted that the transceiver1602includes the Tx antenna array1404and the Rx antenna array1422previously described with reference toFIG.14. However, in the example configuration of the transceiver1602shown inFIG.16, the Tx antenna array1404is situated adjacent to the Rx antenna array1422in the horizontal direction1492. The distance m1670represents the distance between the center point1406of the Tx antenna array1404and the center point1424of the Rx antenna array1422.

FIG.16further illustrates a transmit beam1612formed at the Tx antenna array1404and a receive beam1630formed at the Rx antenna array1422. For example, the wireless communication device1600may form the transmit beam1612to transmit downlink (DL) signals to the UE1450, and may form the receive beam1630to receive uplink (UL) signals from the UE1450.

The wireless communication device1600may determine that the cluster1607formed at the object1416in the wireless communication channel provides the best signal strength and may form the transmit beam1612in a direction toward the cluster1607.

InFIG.16, for example, the direction of the transmit beam1612toward the cluster1607is indicated with the signal transmission path1614. The wireless communication device1600may assume channel reciprocity and may form the receive beam1630toward the cluster1607. InFIG.16, for example, the direction of the receive beam1630toward the cluster1607is indicated with the signal reception path1632. The UE1450may form a beam1618toward the cluster1607for reception of signal transmissions. The UE1450may assume channel reciprocity and may use the beam1618for signal transmissions toward the cluster1607. InFIG.16, for example, the direction of the beam1618toward the cluster1607is indicated with the signal reception path1620and the signal transmission path1634.

The separation of the Tx antenna array1404from the Rx antenna array1422may cause the direction of the transmit beam1612and the direction of the receive beam1630to form an angle θ1636at the cluster1607. In some examples, the angle θ1636may represent the difference between the direction of the transmit beam1612and the direction of the receive beam1630.

In one example, as described with reference toFIG.14, the Tx antenna array1404may be the same size as the Rx antenna array1422and may have the same inter-antenna element spacing. Therefore, NT1may be equal to NR1, NT2may be equal to NR2, a may be equal to c, and b may be equal to d. In this example, the wireless communication device1600may form the transmit beam1612and the receive beam1630based on code-book based discrete Fourier transform (DFT) beams with progressive phase shifts and may set the threshold gain control value S to 3 dB.

Determination of the distance threshold (e.g., Dthreshold_2) for the configuration of the transceiver1602inFIG.16will now be described. For example, the wireless communication device1600may determine that a beam correspondence failure has occurred when the angle θ1636meets or exceeds the 3 dB bandwidth of the transmit beam1612or receive beam1630as shown with the following condition (11):

180π·mD≥γ·100N(11)
where the expression [(180/π)·(m/D)] represents the value of angle θ1636(e.g., as described with reference to equation (4)) and the expression γ·100/N represents the 3 dB bandwidth of the transmit beam1612or receive beam1630as previously described. Since the distance m1670may be expressed as bλ·NT2and the antenna dimension N is represented by NT2, the condition (11) above may be rewritten as shown in the following condition (12):

180π·b⁢λ·NT2D≥γ·100NT2.(12)

The above condition (12) may be solved for the distance (D) to obtain the following condition (13):

D≤1.8π·b⁢λ·NT22γ.(13)

Therefore, since the wireless communication device1600may determine that a beam correspondence failure has occurred when the distance (D) from the Tx antenna array1404or the Rx antenna array1422to the cluster1607(or the object1416) is less than or equal to the result of the expression [(1.8/π)·(bλ·NT22)/γ], the result of the expression [(1.8/π)·(bλ·NT22)/γ] may represent the value of the distance threshold (e.g., Dthreshold_2) for the example ofFIG.16.

FIG.17shows a set of curves illustrating example relationships between the antenna dimension NT2for the Tx antenna array1404and the distance threshold (e.g., Dthreshold_2) for the Tx antenna array1404when b is set to 0.5. For example, curve1702represents the relationship between the antenna dimension NT2and the distance threshold (e.g., Dthreshold_2) for the Tx antenna array1404when operating at a frequency of 30 GHz, curve1704represents the relationship between the antenna dimension NT2and the distance threshold (e.g., Dthreshold_2) for the Tx antenna array1404when operating at a frequency of 60 GHz, and curve1706represents the relationship between the antenna dimension NT2and the distance threshold (e.g., Dthreshold_2) for the Tx antenna array1404when operating at a frequency of 120 GHz. InFIG.17, it should be noted that for a given antenna dimension NT2, the distance threshold (e.g., Dthreshold_2) may be inversely proportional to the frequency of the Tx antenna array1404. For example, when the antenna dimension NT2is 192, the distance threshold (e.g., Dthreshold_2) decreases as the operating frequency increases.

In some aspects of the disclosure, the wireless communication device900may initiate a beam refinement training procedure for the receive beam912or the transmit beam902when the indication of the beam correspondence failure is transmitted to the UE950. The wireless communication device900may determine a refined receive beam or a refined transmit beam based on the beam refinement training procedure.

In some aspects of the disclosure, the wireless communication device900may indicate a mapping of control information for one or more beams (e.g., transmit beams and/or receive beams) to the UE950in response to a determination of a beam correspondence failure. In some examples, the wireless communication device900may indicate the mapping of control information with the indication of the beam correspondence failure. For example, the control information may include at least one of a synchronization signal block (SSB) index or a channel state information reference signal (CSI-RS) index. The mapping of control information for one or more transmit beams may indicate different SSBs for the downlink (DL) and/or the uplink (UL) based on an estimate of the angle θ918. The UE950may use the mapping of control information for the one or more beams to decode SSBs.

FIG.18illustrates a signal flow diagram1800in accordance with various aspects of the present disclosure. The signal flow diagram1800may include a base station1802and a user equipment1804. The base station1802may correspond to the wireless communication device900shown inFIG.9and the UE1804may correspond to the UE950shown inFIG.9.

At1806, the base station1802may form a transmit beam (e.g., transmit beam902inFIG.9) and a receive beam (e.g., receive beam912inFIG.9) for communication with the UE1804.

At1808, the base station1802may monitor a difference between a first direction of the transmit beam and a second direction of the receive beam. For example, the difference between the first direction of the transmit beam and the second direction of the receive beam may be the angle θ918inFIG.9.

At1810, the base station1802may determine that the difference between the first direction of the transmit beam and the second direction of the receive beam is greater than or equal to a beam correspondence threshold. For example, the beam correspondence threshold may be the beamwidth φ (e.g., the beamwidth φ1320) of the transmit beam902based on the signal strength threshold (e.g., the threshold gain value K).

The base station1802may transmit an indication of a beam correspondence failure to the UE1804when the difference (e.g., the angle θ918) between the direction of the transmit beam and the direction of the receive beam is greater than or equal to the beam correspondence threshold. In some examples, the base station1802may transmit a message1812to the UE1804including a bit field for indicating a beam correspondence failure. For example, the base station1802may set a bit in the bit field to a first value (e.g., ‘1’) when a beam correspondence failure has occurred.

The base station1802may further transmit a message1814including a beam refinement training procedure request when a beam correspondence failure has occurred. In some examples, the message1814may be included in the message1812. The beam refinement training procedure request may initiate a beam refinement training procedure with the UE1804to determine a refined transmit beam and/or a refined receive beam.

The base station1802may further transmit a message1816including a control information mapping for at least one beam (e.g., a transmit beam and/or a receive beam) when a beam correspondence failure has occurred. The control information may include at least one of a synchronization signal block (SSB) index or a channel state information reference signal (CSI-RS) index.

FIG.19is a flowchart1900of a method of wireless communication. The method may be performed by a first wireless communication device (e.g., the wireless communication device900,1400,1600; the base station1802; the apparatus2102/2102′; the processing system2214, which may include the memory376and which may be the entire wireless communication device900,1400,1600or base station1802, or a component of the wireless communication device900,1400,1600or the base station1802, such as the TX processor316, the RX processor370, and/or the controller/processor375).

At1902, the first wireless communication device forms a transmit beam in a first direction at a transmit antenna array and a receive beam in a second direction at a receive antenna array, wherein the transmit beam and the receive beam are formed for communication with a second wireless communication device. For example, with reference toFIG.9, the wireless communication device900may form the transmit beam902at the Tx antenna array802and may form the receive beam912at the Rx antenna array852. The transmit beam902and the receive beam912may

At1904, the first wireless communication device monitors a difference between the first direction of the transmit beam and the second direction of the receive beam. In some examples, the difference between the first direction and the second direction may be an angle formed between the first direction and the second direction (e.g., the angle θ918).

In some examples, with reference toFIG.9, the wireless communication device900may monitor the difference between the first direction of the transmit beam and the second direction of the receive beam by determining the difference (e.g., the angle θ918) between the first direction and the second direction based on a size of the transmit antenna array (e.g., the size NT1×NT2of the transmit antenna array802), a size of the receive antenna array (e.g., the size NR1×NR2of the receive antenna array852), the geometry (e.g., shape) of the transmit antenna array802, the geometry (e.g., shape) of the receive antenna array852, an arrangement (e.g., rows, columns) of transmit antenna elements in the transmit antenna array, an arrangement (e.g., rows, columns) of receive antenna elements in the receive antenna array, a set of beam weights associated with the transmit beam (e.g., the transmit beam902), a set of beam weights associated with the receive beam (e.g., the receive beam912), a distance between the transmit antenna array802and the receive antenna array852(e.g., the distance m between the center of the transmit antenna array802(e.g., at center point804) and the center of the receive antenna array852(e.g., at center point854)), and/or a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices (e.g., a distance between the center point804of the transmit antenna array802to the cluster907). For example, the wireless communication device900may apply one or more of the values above, or a combination of the values above, to equation (4) or equation (5) to determine the angle θ918.

In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include determining a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices (e.g., a distance between the center point804of the transmit antenna array802to the cluster907) and determining the difference between the first direction and the second direction based on the distance. For example, the wireless communication device900may apply the distance between the center point804of the transmit antenna array802to the cluster907to equation (4) or equation (5) to determine the angle θ918.

In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster by estimating a distance from the first wireless communication device to the second wireless communication device. In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster based on a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals. In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster by receiving, from the second wireless communication device, at least one of a path loss estimate or information indicating a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals, and determining the distance from the transmit antenna array or the receive antenna array to the cluster based on the path loss estimate or the location of the at least one object capable of reflecting, diffracting or scattering wireless communication signals.

In some examples, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include determining a distance from the first wireless communication device to a cluster in a channel over which energy is steered between the first and second wireless communication devices, and determining the difference (e.g., the angle θ918) between the first and second directions based on the distance. For example, the first wireless communication device may apply the distance between the center point804of the transmit antenna array802to the cluster907to equation (4) or equation (5) to determine the angle θ918.

In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include comparing the difference (e.g., the angle θ918) between the direction of the transmit beam and the direction of the receive beam to the beam correspondence threshold. For example, the beam correspondence threshold may be the beamwidth (p (e.g., the beamwidth (p1320) corresponding to the signal strength threshold (e.g., the threshold gain value K). In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include comparing the estimated distance (e.g., Dest) to a distance threshold (e.g., Dthreshold, Dthreshold_1, or Dthreshold_2).

Finally, at1906, the first wireless communication device transmits an indication (e.g., message1812inFIG.18) of a beam correspondence failure to the second wireless communication device when the difference between the first direction and the second direction is greater than or equal to the beam correspondence threshold. For example, the beam correspondence threshold may be the beamwidth φ (e.g., the beamwidth φ1320) corresponding to the signal strength threshold (e.g., the threshold gain value K).

FIGS.20A and20Bare a flowchart2000of a method of wireless communication. The method may be performed by a first wireless communication device (e.g., the wireless communication device900,1400,1600; the base station1802; the apparatus2102/2102′; the processing system2214, which may include the memory376and which may be the entire wireless communication device900,1400,1600or base station1802, or a component of the wireless communication device900,1400,1600or the base station1802, such as the TX processor316, the RX processor370, and/or the controller/processor375). InFIGS.20A and20B, operations shown in dashed lines represent optional operations.

At2002, the first wireless communication device forms a transmit beam in a first direction at a transmit antenna array and a receive beam in a second direction at a receive antenna array, wherein the transmit beam and the receive beam are formed for communication with a second wireless communication device. For example, with reference toFIG.9, the wireless communication device900may form the transmit beam902at the Tx antenna array802and may form the receive beam912at the Rx antenna array852. The transmit beam902and the receive beam912may be formed for communication with the UE950.

At2004, the first wireless communication device determines a signal strength threshold for the transmit beam or the receive beam. For example, with reference toFIG.13, the signal strength threshold may be the previously described threshold gain value K. In some examples, the first wireless communication device may determine the signal strength threshold for the transmit beam or the receive beam by determining a difference between a peak gain value for the transmit beam or the receive beam (e.g., the peak gain value G inFIG.13) and a threshold gain control value (e.g., the threshold gain control value S1306inFIG.13). In some examples, the first wireless communication device may determine the threshold gain control value S to be 3 dB. In other examples, the first wireless communication device may determine the threshold gain control value S to be a value less than 3 dB or greater than 3 dB. In some examples, the first wireless communication device may determine the threshold gain control value S in coordination with a second wireless communication device (e.g., UE950, a CPE) in the network.

At2006, the first wireless communication device determines a beamwidth (e.g., beamwidth φ) of the transmit beam or a beamwidth of the receive beam based on the signal strength threshold. For example, with reference toFIG.13, the first wireless communication device may locate the points where the pattern of the transmit beam902intersects the signal strength threshold (e.g., the points1308,1310along the dotted line indicating the threshold gain value K). The beamwidth φ(e.g., the beamwidth φ1320) may be defined between these points (e.g., the points1308,1310).

At2008, the first wireless communication device determines a beam correspondence threshold based on the beamwidth of the transmit beam or the beamwidth of the receive beam. In some examples, the first wireless communication device may determine the beam correspondence threshold to be the beamwidth φ (e.g., the beamwidth φ1320) of the transmit beam902based on the signal strength threshold (e.g., the threshold gain value K).

At2010, the first wireless communication device estimates a distance (e.g., Dest) from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices. In some examples, with reference toFIG.9, the wireless communication device900may estimate the distance from the transmit antenna array802or the receive antenna array852to the cluster907in the wireless communication channel by estimating the distance from the wireless communication device900to the UE950based on a location of the UE950. For example, the wireless communication device900may determine the location of the UE950based on a positioning algorithm that indicates the location of the UE950.

For example, in scenarios where the wireless communication device900does not have a line of sight (LOS) to a second wireless communication device (e.g., the UE950), the distance from the Tx antenna array802or the Rx antenna array852to the cluster907may be different from the distance from the Tx antenna array802or the Rx antenna array852to the second wireless communication device (e.g., the UE950). In these scenarios, the wireless communication device900may estimate the distance from the Tx antenna array802or the Rx antenna array852to the cluster907in the wireless communication channel based on a location of an object (e.g., the object906) capable of reflecting, diffracting or scattering wireless communication signals.

In some examples, the wireless communication device900may determine the distance to the cluster907based on the location of the wireless communication device900and information about the static environment around the wireless communication device900(e.g., installation information indicating locations of buildings, fixtures, or other structures). In some examples, the wireless communication device900may use path loss estimates from the second wireless communication device (e.g., the UE950) in combination with the location of the wireless communication device900and information about the static environment around the wireless communication device900to estimate the distance between the wireless communication device900and the cluster907.

At2012, the first wireless communication device monitors a difference between the first direction of the transmit beam and the second direction of the receive beam. In some examples, the difference between the first direction and the second direction may be an angle formed between the first direction and the second direction (e.g., the angle θ918).

In some examples, with reference toFIG.9, the wireless communication device900may monitor the difference between the first direction of the transmit beam and the second direction of the receive beam by determining the difference (e.g., the angle θ918) between the first direction and the second direction based on a size of the transmit antenna array (e.g., the size NT1×NT2of the transmit antenna array802), a size of the receive antenna array (e.g., the size NR1×NR2of the receive antenna array852), the geometry (e.g., shape) of the transmit antenna array802, the geometry (e.g., shape) of the receive antenna array852, an arrangement (e.g., rows, columns) of transmit antenna elements in the transmit antenna array, an arrangement (e.g., rows, columns) of receive antenna elements in the receive antenna array, a set of beam weights associated with the transmit beam (e.g., the transmit beam902), a set of beam weights associated with the receive beam (e.g., the receive beam912), a distance between the transmit antenna array802and the receive antenna array852(e.g., the distance m between the center of the transmit antenna array802(e.g., at center point804) and the center of the receive antenna array852(e.g., at center point854)), and/or a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices (e.g., a distance between the center point804of the transmit antenna array802to the cluster907). For example, the wireless communication device900may apply one or more of the values above, or a combination of the values above, to equation (4) or equation (5) to determine the angle θ918.

In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include determining a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices (e.g., a distance between the center point804of the transmit antenna array802to the cluster907) and determining the difference between the first direction and the second direction based on the distance. For example, the wireless communication device900may apply the distance between the center point804of the transmit antenna array802to the cluster907to equation (4) or equation (5) to determine the angle θ918.

In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster by estimating a distance from the first wireless communication device to the second wireless communication device. In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster based on a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals. In some examples, the first wireless communication device may determine the distance from the transmit antenna array or the receive antenna array to the cluster by receiving, from the second wireless communication device, at least one of a path loss estimate or information indicating a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals, and determining the distance from the transmit antenna array or the receive antenna array to the cluster based on the path loss estimate or the location of the at least one object capable of reflecting, diffracting or scattering wireless communication signals.

In some examples, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include determining a distance from the first wireless communication device to a cluster in a channel over which energy is steered between the first and second wireless communication devices, and determining the difference (e.g., the angle θ918) between the first and second directions based on the distance. For example, the first wireless communication device may apply the distance between the center point804of the transmit antenna array802to the cluster907to equation (4) or equation (5) to determine the angle θ918.

In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include comparing the difference (e.g., the angle θ918) between the direction of the transmit beam and the direction of the receive beam to the beam correspondence threshold. For example, the beam correspondence threshold may be the beamwidth p (e.g., the beamwidth φ1320) corresponding to the signal strength threshold (e.g., the threshold gain control value S). In some aspects of the disclosure, monitoring the difference between the first direction of the transmit beam and the second direction of the receive beam may include comparing the estimated distance (e.g., Dest) to a distance threshold (e.g., Dthreshold, Dthreshold_1, or Dthreshold_2).

At2014, the first wireless communication device transmits an indication of a beam correspondence failure (e.g., message1812inFIG.18) to the second wireless communication device when the difference between the first direction and the second direction is greater than or equal to the beam correspondence threshold. For example, the beam correspondence threshold may be the beamwidth φ (e.g., the beamwidth (p1320) corresponding to the signal strength threshold (e.g., the threshold gain value K).

At2016, the first wireless communication device transmits the indication of the beam correspondence failure to the second wireless communication device when the estimated distance (e.g., Dest) is less than or equal to the distance threshold (e.g., Dthreshold, Dthreshold_1, or Dthreshold_2). In some examples, the distance threshold (e.g., Dthreshold, Dthreshold_1, or Dthreshold_2) is a value based on at least one of a beamwidth of the transmit beam or the receive beam, a size of the transmit antenna array, a size of the receive antenna array, a spacing of transmit antenna elements in the transmit antenna array, a spacing of receive antenna elements in the receive antenna array, or a beamwidth factor (e.g., the beamwidth factor γ described in detail herein).

At2018, the first wireless communication device initiates a beam refinement training procedure for the receive beam or the transmit beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device. For example, the beam refinement training procedure for the receive beam or the transmit beam may include the separate beam training procedures described with reference toFIG.10.

At2020, the first wireless communication device determines a refined receive beam or a refined transmit beam based on the beam refinement training procedure. The refined receive beam or the refined transmit beam may provide increased gain and may improve the performance of the first wireless communication device and/or the second wireless communication device.

At2022, the first wireless communication device indicates, to the second wireless communication device, a mapping of control information for at least one beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device. In some examples, the control information includes at least one of a synchronization signal block (SSB) index or a channel state information reference signal (CSI-RS) index.

FIG.21is a conceptual data flow diagram2100illustrating the data flow between different means/components in an example apparatus2102. The apparatus2102(also referred to as a first wireless communication device) may be a base station. The apparatus includes a reception component2104that receives UL signals from a second wireless communication device (e.g., the UE2180). For example, the UL signals may include the signal2154including a path loss estimate and/or location information (e.g., information indicating a location of at least one object (e.g.,906,1416) capable of reflecting, diffracting or scattering wireless communication signals).

The apparatus further includes a beam formation component2106that forms a transmit beam in a first direction at the transmit antenna array (e.g., the Tx antenna array2125coupled to the transmission component2124) and a receive beam in a second direction at the receive antenna array (e.g., the Rx antenna array2105coupled to the reception component2104), wherein the transmit beam and the receive beam are formed for communication with the second wireless communication device (e.g., the UE2180). For example, the beam formation component2106may provide a set of beam weights2126to be applied at the Rx antenna array2105, and a set of beam weights2128to be applied at the Tx antenna array2125.

The apparatus further includes a distance estimation component2108that estimates a distance from the transmit antenna array (e.g., the Tx antenna array2125) or the receive antenna array (e.g., the Rx antenna array2105) to a cluster in a channel over which energy is steered between the first and second wireless communication devices (e.g., between the apparatus2102and the UE2180). In some examples, the distance estimation component2108may use the path loss estimate and/or location information received via the signal2154to obtain the estimated distance2132.

The apparatus further includes a monitor component2110that monitors a difference between the first direction of the transmit beam and the second direction of the receive beam. The monitor component2110may provide a signal2134indicating whether a beam correspondence failure has occurred. For example, the signal2134may indicate a beam correspondence failure has occurred when the monitor component2110determines that the difference between the first direction and the second direction is greater than or equal to a beam correspondence threshold. In another example, the signal2134may indicate a beam correspondence failure has occurred when the monitor component2110determines that the estimated distance2132is less than or equal to a distance threshold.

The apparatus further includes a beam correspondence failure indication transmission component2112that transmits an indication of a beam correspondence failure2136(e.g., via the transmission component2124) to the second wireless communication device (e.g., the UE2180) when the difference between the first direction and the second direction is greater than or equal to the beam correspondence threshold or when the estimated distance2132is less than or equal to a distance threshold.

The apparatus further includes a signal strength threshold determination component2114that determines a signal strength threshold2138(e.g., the threshold gain value K) for the transmit beam or the receive beam. In some examples, the apparatus determines the signal strength threshold for the transmit beam or the receive beam by determining a difference between a peak gain value for the transmit beam or the receive beam (e.g., the peak gain value G) and the threshold gain control value (e.g., the threshold gain control value S).

The apparatus further includes a beamwidth determination component2116that determines the beamwidth2140(e.g., the beamwidth φ1320based on the points1308and1310inFIG.13) of the transmit beam or the beamwidth of the receive beam based on the signal strength threshold (e.g., the threshold gain value K).

The apparatus further includes a beam correspondence threshold determination component2118that determines a beam correspondence threshold2142based on a beamwidth of the transmit beam or a beamwidth of the receive beam. In some examples, the beam correspondence threshold2142may be the beamwidth2140(e.g., the beamwidth φ1320based on the points1308and1310inFIG.13).

The apparatus further includes a control information mapping indication component2120that indicates, to the second wireless communication device (e.g., the UE2180), a mapping of control information2152for at least one beam when the indication of the beam correspondence failure2136is transmitted to the second wireless communication device. For example, the control information may include a synchronization signal block (SSB) index and/or a channel state information reference signal (CSI-RS) index.

The apparatus further includes a beam refinement training procedure component2122that initiates a beam refinement training procedure (e.g., via the beam refinement training procedure request2146) for the receive beam or the transmit beam when the indication of the beam correspondence failure2136is transmitted to the second wireless communication device (e.g., the UE2180). The beam refinement training procedure component2122may control the Rx antenna array2105via the data path2148and the Tx antenna array2125via the data path2150to perform the beam refinement training procedure to determine a refined receive beam and/or a refined transmit beam.

The apparatus further includes a transmission component2124that transmits DL signals to the second wireless communication device (e.g., the UE2180). The DL signals may include the indication of the beam correspondence failure2136, the beam refinement training procedure request2146, and/or the mapping of control information2152for at least one beam.

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts ofFIGS.19,20A,20B. As such, each block in the aforementioned flowcharts ofFIGS.19,20A,20Bmay 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.22is a diagram2200illustrating an example of a hardware implementation for an apparatus2102′ employing a processing system2214. The processing system2214may be implemented with a bus architecture, represented generally by the bus2224. The bus2224may include any number of interconnecting buses and bridges depending on the specific application of the processing system2214and the overall design constraints. The bus2224links together various circuits including one or more processors and/or hardware components, represented by the processor2204, the components2104,2106,2108,2110,2112,2114,2116,2118,2120,2122, and2124and the computer-readable medium/memory2206. The bus2224may 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 system2214may be coupled to a transceiver2210. The transceiver2210is coupled to one or more antennas2220. The transceiver2210provides a means for communicating with various other apparatus over a transmission medium. The transceiver2210receives a signal from the one or more antennas2220, extracts information from the received signal, and provides the extracted information to the processing system2214, specifically the reception component2104. In addition, the transceiver2210receives information from the processing system2214, specifically the transmission component2124, and based on the received information, generates a signal to be applied to the one or more antennas2220. The processing system2214includes a processor2204coupled to a computer-readable medium/memory2206. The processor2204is responsible for general processing, including the execution of software stored on the computer-readable medium/memory2206. The software, when executed by the processor2204, causes the processing system2214to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory2206may also be used for storing data that is manipulated by the processor2204when executing software. The processing system2214further includes at least one of the components2104,2106,2108,2110,2112,2114,2116,2118,2120,2122, and2124. The components may be software components running in the processor2204, resident/stored in the computer readable medium/memory2206, one or more hardware components coupled to the processor2204, or some combination thereof. The processing system2214may 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 system2214may be the entire base station (e.g., see310ofFIG.3).

In one configuration, the apparatus2102/2102′ for wireless communication includes means for forming a transmit beam in a first direction at the transmit antenna array and a receive beam in a second direction at the receive antenna array, wherein the transmit beam and the receive beam are formed for communication with a second wireless communication device, means for monitoring a difference between the first direction of the transmit beam and the second direction of the receive beam, means for transmitting an indication of a beam correspondence failure to the second wireless communication device when the difference between the first direction and the second direction is greater than or equal to a beam correspondence threshold, means for determining the beam correspondence threshold based on a beamwidth of the transmit beam or a beamwidth of the receive beam, means for determining a signal strength threshold for the transmit beam or the receive beam, means for determining the beamwidth of the transmit beam or the beamwidth of the receive beam based on the signal strength threshold, means for estimating a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices, means for transmitting the indication of the beam correspondence failure to the second wireless communication device when the estimated distance is less than or equal to a distance threshold, means for initiating a beam refinement training procedure for the receive beam or the transmit beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device, means for determining a refined receive beam or a refined transmit beam based on the beam refinement training procedure, means for indicating, to the second wireless communication device, a mapping of control information for at least one beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device.

The aforementioned means may be one or more of the aforementioned components of the apparatus2102and/or the processing system2214of the apparatus2102′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system2214may 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.

In the aspects described herein, a first wireless communication device (e.g., a base station) including separate Tx and Rx antenna arrays may dynamically determine any occurrences of beam correspondence failures by monitoring the difference between the direction of a transmit beam and the direction of a receive beam. The first wireless communication device may compare the difference between the direction of the transmit beam and the direction of the receive beam to an appropriate beam correspondence threshold to determine any occurrences of beam correspondence failures.

The dynamic determination of beam correspondence failures according to the aspects described herein may enable the first wireless communication device to assume channel reciprocity when forming the transmit and receive beams for communication with a second wireless communication device (e.g., a UE), and to selectively perform a separate beam training procedure for the receive beam and/or the transmit beam in response to a beam correspondence failure. Therefore, the aspects described herein may allow the first wireless communication device to avoid delays and reduce the network overhead typically associated with separate beam training procedures for transmit and receive beams.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method for a first wireless communication device including a transmit antenna array and a receive antenna array, the transmit antenna array being separate from the receive antenna array, comprising: forming a transmit beam in a first direction at the transmit antenna array and a receive beam in a second direction at the receive antenna array, wherein the transmit beam and the receive beam are formed for communication with a second wireless communication device; monitoring a difference between the first direction of the transmit beam and the second direction of the receive beam; and transmitting an indication of a beam correspondence failure to the second wireless communication device when the difference between the first direction and the second direction is greater than or equal to a beam correspondence threshold.

Aspect 2: The method of aspect 1, wherein monitoring the difference between the first direction and the second direction comprises determining the difference between the first direction and the second direction based on at least one of a size of the transmit antenna array, a size of the receive antenna array, an arrangement of transmit antenna elements in the transmit antenna array, an arrangement of receive antenna elements in the receive antenna array, a set of beam weights associated with the transmit beam, a set of beam weights associated with the receive beam, a distance between the transmit antenna array and the receive antenna array, or a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices.

Aspect 3: The method of aspect 1 or 2, wherein the difference between the first direction and the second direction is an angle formed between the first direction and the second direction.

Aspect 4: The method of any one of aspects 1 through 3, further comprising: determining the beam correspondence threshold based on a beamwidth of the transmit beam or a beamwidth of the receive beam.

Aspect 5: The method of aspect 4, further comprising: determining a signal strength threshold for the transmit beam or the receive beam; and determining the beamwidth of the transmit beam or the beamwidth of the receive beam based on the signal strength threshold.

Aspect 6: The method of aspect 5, wherein determining the signal strength threshold for the transmit beam or the receive beam comprises: determining a difference between a peak gain value for the transmit beam or the receive beam and a threshold gain control value.

Aspect 7: The method of any one of aspects 1 through 6, wherein monitoring the difference between the first direction and the second direction comprises: determining a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices; and determining the difference between the first direction and the second direction based on the distance.

Aspect 8: The method of aspect 7, wherein determining the distance from the transmit antenna array or the receive antenna array to the cluster in the channel which steers the energy between the first and second wireless communication devices comprises estimating a distance from the first wireless communication device to the second wireless communication device.

Aspect 9: The method of aspect 7, wherein the distance from the transmit antenna array or the receive antenna array to the cluster in the channel which steers the energy between the first and second wireless communication devices is determined based on a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals.

Aspect 10: The method of aspect 7, wherein determining the distance from the transmit antenna array or the receive antenna array to the cluster in the channel which steers the energy between the first and second wireless communication devices comprises: receiving, from the second wireless communication device, at least one of a path loss estimate or information indicating a location of at least one object capable of reflecting, diffracting or scattering wireless communication signals; and determining the distance from the transmit antenna array or the receive antenna array to the cluster based on the path loss estimate or the location of the at least one object capable of reflecting, diffracting or scattering wireless communication signals.

Aspect 11: The method of any one of aspects 1 through 6, wherein monitoring the difference between the first direction and the second direction comprises: determining a distance from the first wireless communication device to a cluster in a channel over which energy is steered between the first and second wireless communication devices; and determining the difference between the first and second directions based on the distance.

Aspect 12: The method of any one of aspects 1 through 11, further comprising: estimating a distance from the transmit antenna array or the receive antenna array to a cluster in a channel over which energy is steered between the first and second wireless communication devices; and transmitting the indication of the beam correspondence failure to the second wireless communication device when the estimated distance is less than or equal to a distance threshold.

Aspect 13: The method of aspect 12, wherein the distance threshold is a value based on at least one of a beamwidth of the transmit beam or the receive beam, a size of the transmit antenna array, a size of the receive antenna array, a spacing of transmit antenna elements in the transmit antenna array, a spacing of receive antenna elements in the receive antenna array, or a beamwidth factor.

Aspect 14: The method of any one of aspects 1 through 13, further comprising: initiating a beam refinement training procedure for the receive beam or the transmit beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device; and determining a refined receive beam or a refined transmit beam based on the beam refinement training procedure.

Aspect 15: The method of aspect 14, further comprising: indicating, to the second wireless communication device, a mapping of control information for at least one beam when the indication of the beam correspondence failure is transmitted to the second wireless communication device.

Aspect 16: The method of aspect 15, wherein the control information includes at least one of a synchronization signal block (SSB) index or a channel state information reference signal (CSI-RS) index.

Aspect 17: An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory and configured to perform a method of any one of aspects 1 through 16.

Aspect 18: An apparatus for wireless communication comprising at least one means for performing a method of any one of aspects 1 through 16.

Aspect 19: A computer-readable medium storing computer executable code, the code when executed by a processor cause the processor to perform a method of any one of aspects 1 through 16.

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.” 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.”