Sidelink beam obstruction detection

Abstract

Various aspects of the present disclosure generally relate to wireless communications. In some aspects, a first node may transmit a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determine, based at least in part on the first signal, whether a second signal is received on the beamformed link from the second node to the first node; and transmit a third signal based at least in part on receiving the second signal or perform a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received. Numerous other aspects are provided.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 62 / 969,544, filed February 3, 2020, entitled “SIDELINK BEAM FAILURE DETECTION,” and U.S. Non-Provisional Patent Application No. 17 / 248,162, filed January 12, 2021, entitled “SIDELINK BEAM FAILURE DETECTION,” which are expressly incorporated herein by reference.

[0002] Aspects of the present disclosure relate generally to wireless communications and to techniques and apparatus for sidelink beam failure detection. [Background technology]

[0003] Wireless communication systems have been widely deployed to provide various telecommunication services, such as telephone, video, data, messaging, and broadcast. A typical wireless communication system may utilize multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / LTE-Advanced is a set of extensions to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the 3rd Generation Partnership Project (3GPP®).

[0004] A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipments (UEs). The UEs may communicate with the BSs via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As described in more detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit receive point (TRP), new radio (NR) BS, 5G Node B, etc.

[0005] The above multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that allows various user equipment to communicate at city, national, regional, and even global levels. NR, sometimes referred to as 5G, is a set of extensions to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, improving services, utilizing new spectrum, and using Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) (CP-OFDM) on the downlink (DL) and CP-OFDM and / or SC-FDM (also known as Discrete Fourier Transform Spread OFDM (DFT-s-OFDM)) on the uplink (UL) to better integrate with other open standards, as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to grow, further improvements in LTE and NR technologies are needed. Preferably, these improvements should be applicable to other multiple access technologies and telecommunications standards that utilize these technologies. Summary of the Invention [Means for solving the problem]

[0006] In some aspects, a method of wireless communication implemented by a first node may include transmitting a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determining, based at least in part on the first signal, whether a second signal is received on the beamformed link from the second node to the first node; and transmitting a third signal on the beamformed link from the first node to the second node based at least in part on receiving the second signal or performing a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received.

[0007] In some aspects, a method of wireless communication implemented by a second node may include determining whether a first signal is received from the first node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determining whether to transmit a second signal on the beamformed link from the second node to the first node based at least in part on whether the first signal is received; and receiving a third signal based at least in part on the second signal or performing a sidelink beam failure recovery procedure based at least in part on a failure to receive the first signal or the third signal.

[0008] In some aspects, a first node for wireless communication may include a memory and one or more processors operably coupled to the memory. The memory or the one or more processors may be configured to: transmit a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determine whether a second signal is received on the beamformed link from the second node to the first node based at least in part on the first signal; transmit a third signal based at least in part on receiving the second signal or perform a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received.

[0009] In some aspects, a second node for wireless communication may include a memory and one or more processors operably coupled to the memory. The memory or the one or more processors may be configured to: determine whether a first signal is received from the first node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determine whether to transmit a second signal on the beamformed link from the second node to the first node based at least in part on whether the first signal is received; receive a third signal based at least in part on the second signal or perform a sidelink beam failure recovery procedure based at least in part on a failure to receive the first signal or the third signal.

[0010] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication that, when executed by one or more processors of a first node, may cause the one or more processors to: transmit a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determine based at least in part on the first signal whether a second signal is received on the beamformed link from the second node to the first node; transmit a third signal based at least in part on receiving the second signal or perform a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received.

[0011] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication that, when executed by one or more processors of a second node, may cause the one or more processors to determine whether a first signal is received from the first node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing, determine whether to transmit a second signal on the beamformed link from the second node to the first node based at least in part on whether the first signal is received, and receive a third signal based at least in part on the second signal or perform a sidelink beam failure recovery procedure based at least in part on a failure to receive the first signal or the third signal.

[0012] In some aspects, an apparatus for wireless communication may include means for transmitting a first signal to a second node on a beamformed link from the apparatus to the second node, where the apparatus and the second node are associated with a common timing; means for determining whether a second signal is received on the beamformed link from the second node to the apparatus based at least in part on the first signal; and means for transmitting a third signal on the beamformed link from the first node to the second node based at least in part on receiving the second signal or performing a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received.

[0013] In some aspects, an apparatus for wireless communication may include means for determining whether a first signal is received from a first node on a beamformed link from the first node to the apparatus, where the first node and the apparatus are associated with a common timing; means for determining whether to transmit a second signal based at least in part on whether the first signal is received on the beamformed link from the apparatus to the first node; and means for receiving a third signal based at least in part on the second signal or means for performing a sidelink beam failure recovery procedure based at least in part on a failure to receive the first signal or the third signal.

[0014] Aspects generally include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems as fully described herein with reference to the drawings and as illustrated in the accompanying drawings and this specification.

[0015] The foregoing has outlined rather broadly the features and technical advantages of examples according to the present disclosure so that the following detailed description may be better understood. Additional features and advantages are described below. The concepts and examples disclosed may be readily used as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent structures do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both their organization and methods of operation, together with associated advantages, will be better understood from the following description when considered in conjunction with the accompanying drawings. Each of the figures is provided for the purpose of illustration and explanation, and not as a definition of the limits of the claims.

[0016] So that the above-mentioned features of the present disclosure may be understood in detail, the contents briefly summarized above may be more particularly described by referring to the embodiments, some of which are shown in the attached drawings. However, since the present description may admit of other equally effective embodiments, it should be noted that the attached drawings show only some typical embodiments of the present disclosure and therefore should not be considered as limiting its scope. The same reference numbers in different drawings may identify the same or similar elements. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram illustrating an example of a wireless communication network in accordance with various aspects of the present disclosure. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a base station in communication with a UE in a wireless communication network, in accordance with various aspects of the present disclosure. [Diagram 3] FIG. 1 illustrates an example of sidelink communication in accordance with various aspects of the present disclosure. [Figure 4] FIG. 1 illustrates examples of sidelink and access link communications in accordance with various aspects of the present disclosure. [Diagram 5] FIG. 1 illustrates an example of sidelink beam failure detection and recovery according to various aspects of the present disclosure. [Figure 6]FIG. 1 illustrates an example of sidelink beam failure detection and recovery according to various aspects of the present disclosure. [Figure 7] FIG. 1 illustrates an example of sidelink beam failure detection and recovery according to various aspects of the present disclosure. [Figure 8] FIG. 1 illustrates an example of sidelink beam failure detection and recovery according to various aspects of the present disclosure. [Figure 9] 1 illustrates an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure. [Figure 10] 1 illustrates an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout the present disclosure. Rather, these aspects are designed so that this disclosure will be exhaustive and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art will appreciate that the scope of the present disclosure encompasses any aspect of the present disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects described herein. In addition, the scope of the present disclosure encompasses an apparatus or method practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present disclosure described herein. It will be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of a claim.

[0019] Several aspects of a telecommunications system are now presented with reference to various apparatus and techniques. These apparatus and techniques are described in the detailed description that follows and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and the like (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0020] Although aspects may be described herein using terminology commonly associated with 5G or NR radio access technologies (RATs), it should be noted that aspects of the present disclosure may apply to other RATs, such as 3G RATs, 4G RATs, and / or RATs subsequent to 5G (e.g., 6G).

[0021] FIG. 1 illustrates a wireless network 100 in which aspects of the disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include several BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UE) and may also be referred to as a base station, NR BS, Node B, gNB, 5G Node B (NB), access point, transmit reception point (TRP), etc. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to the coverage area of ​​a BS and / or a BS subsystem serving this coverage area, depending on the context in which the term is used.

[0022] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., a few kilometers in radius) and may allow unrestricted access by UEs with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “Node B,” “5G NB,” and “cell” may be used interchangeably herein.

[0023] In some aspects, the cells may not necessarily be stationary and the geographic area of ​​the cells may move according to the location of the mobile BS. In some aspects, the BSs may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces, such as direct physical connections, virtual networks, etc., using any suitable transport network.

[0024] The wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send the transmission of the data to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in FIG. 1, a relay BS 110d may communicate with the BS 110a and the UE 120d to facilitate communication between the macro BS 110a and the UE 120d. A relay BS may also be referred to as a relay station, a relay base station, a relay, etc.

[0025] Wireless network 100 may be a heterogeneous network including different types of BSs, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5-40 watts), while a pico BS, femto BS, and relay BS may have a lower transmit power level (e.g., 0.1-2 watts).

[0026] A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with each other directly or indirectly, e.g., via wireless or wireline backhaul.

[0027] The UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout the wireless network 100, and each UE may be fixed or mobile. A UE may also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. A UE may be a cellular phone (e.g., a smartphone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or satellite radio), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate over a wireless or wired medium.

[0028] Some UEs may be considered as machine type communication (MTC) UEs or evolved or enhanced machine type communication (eMTC) UEs. MTC UEs and eMTC UEs include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, a location tag, etc. that may communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered as Internet of Things (IoT) devices and / or may be implemented as NB-IoT (Narrowband Internet of Things) devices. Some UEs may be considered as Customer Premises Equipment (CPE). The UE 120 may be included in a housing that stores components of the UE 120, such as a processor component, a memory component, etc.

[0029] In general, any number of wireless networks may be deployed within a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate at one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT within a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0030] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly (e.g., without using the base station 110 as an intermediary for communicating with each other) using one or more sidelink channels. For example, the UEs 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (which may include, e.g., vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, etc. In this case, the UEs 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by the base station 110.

[0031] The devices of the wireless network 100 may communicate using an electromagnetic spectrum, which may be sub-divided into various classes, bands, channels, etc. based on frequency or wavelength. For example, the devices of the wireless network 100 may communicate using an operating band having a first frequency range (FR1), which may range from 410 MHz to 7.125 GHz, and / or may communicate using an operating band having a second frequency range (FR2), which may range from 24.25 GHz to 52.6 GHz. Frequencies between FR1 and FR2 may be referred to as mid-band frequencies. Although portions of FR1 are higher than 6 GHz, FR1 is often referred to as the "sub-6 GHz" band. Similarly, FR2 is often referred to as the "millimeter wave" band, even though it is different from the extremely high frequency (EHF) band (30 GHz-300 GHz) identified as the "millimeter wave" band by the International Telecommunications Union (ITU). Thus, unless otherwise specified, it should be understood that terms such as "sub-6 GHz," as used herein, may broadly refer to frequencies below 6 GHz, frequencies within FR1, and / or mid-band frequencies (e.g., greater than 7.125 GHz). Similarly, unless otherwise specified, it should be understood that terms such as "millimeter wave," as used herein, may broadly refer to frequencies within the EHF band, frequencies within FR2, and / or mid-band frequencies (e.g., less than 24.25 GHz). It is contemplated that the frequencies included in FR1 and FR2 may be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0032] As indicated above, Figure 1 is given as an example. Other examples may differ from the example described with respect to Figure 1.

[0033] 2 shows a block diagram of a design 200 of a base station 110 and a UE 120, which may be one of the base stations and one of the UEs in FIG. 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T≧1 and R≧1.

[0034] At the base station 110, the transmit processor 220 may receive data for one or more UEs from a data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS selected for the UE, and provide data symbols to all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, higher layer signaling, etc.) and provide overhead and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The T downlink signals from the modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, synchronization signals can be generated using positional coding to convey additional information.

[0035] At the UE 120, the antennas 252a-252r may receive downlink signals from the base station 110 and / or other base stations and may provide received signals to demodulators (DEMODs) 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols and provide decoded data for the UE 120 to a data sink 260 and provide decoded control and system information to the controller / processor 280. The channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 120 may be included in a housing.

[0036] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280. The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a-254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 120 and other UEs may be received by the antennas 234, processed by the demodulator 232, detected by a MIMO detector 236 if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0037] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other components of FIG. 2 may perform one or more techniques associated with sidelink beam failure detection, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other components of FIG. 2 may perform or direct the operation of, for example, process 900 of FIG. 9, process 1000 of FIG. 10, and / or other processes as described herein. The memory 242 and the memory 282 may store data and program codes for the base station 110 and the UE 120, respectively. In some aspects, the memory 242 and / or the memory 282 may include a non-transitory computer-readable medium that stores one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors at the base station 110 and / or the UE 120, may perform or direct operation of, for example, process 900 in FIG. 9, process 1000 in FIG. 10, and / or other processes as described herein. The scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0038] In some aspects, a node (e.g., UE 120 or BS 110) may include means for transmitting a first signal to the second node on a beamformed link from the first node to the second node, means for determining whether a second signal is received on the beamformed link from the second node to the first node based at least in part on the first signal, means for transmitting a third signal on the beamformed link from the first node to the second node based at least in part on receiving the second signal, means for performing a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received, and means for determining whether the first signal is received from the first node to the second node. The sidelink beam failure recovery procedure may include means for determining whether a sidelink signal is received from the first node on a beamformed link to the first node, means for determining whether to transmit a second signal on the beamformed link from the second node to the first node based at least in part on whether the first signal is received, means for receiving a third signal based at least in part on the second signal, means for performing a sidelink beam failure recovery procedure based at least in part on failing to receive the first signal or the third signal, means for performing a sidelink beam failure recovery procedure based at least in part on failing to receive one or more of the first signal or the third signal a threshold number of times, etc. In some aspects, such means may include one or more components of the UE 120 or BS 110 described in connection with FIG. 2, such as the controller / processor 280, the transmit processor 264, the TX MIMO processor 266, the MOD 254, the antennas 252, the DEMOD 254, the MIMO detector 256, the receive processor 258, the antennas 234, the DEMOD 232, the MIMO detector 236, the receive processor 238, the controller / processor 240, the transmit processor 220, the TX MIMO processor 230, the MOD 232, the antennas 234, etc.

[0039] As noted above, Figure 2 is provided as an example. Other examples may differ from those described with respect to Figure 2.

[0040] FIG. 3 is a diagram illustrating an example sidelink communication 300 in accordance with various aspects of the present disclosure.

[0041] 3, a first UE 305-1 may communicate with a second UE 305-2 (and one or more other UEs 305) via one or more sidelink channels 310. The UEs 305-1 and 305-2 may communicate using one or more sidelink channels 310 for P2P communication, D2D communication, V2X communication (e.g., may include V2V communication, V2I communication, V2P communication, etc.), mesh networking, etc. In some aspects, the UEs 305 (e.g., the UEs 305-1 and / or UEs 305-2) may correspond to one or more other UEs described elsewhere herein, such as the UE 120. In some aspects, the one or more sidelink channels 310 may use a ProSe sidelink (PC5) interface and / or operate in a high frequency band (e.g., the 5.9 GHz band). Additionally or alternatively, the UE 305 may use Global Navigation Satellite System (GNSS) timing to synchronize the timing of transmission time intervals (TTIs) (e.g., frames, subframes, slots, symbols, etc.) or the timing of base stations 110 associated with one or more of the UEs 305.

[0042] 3, the one or more sidelink channels 310 may include a physical sidelink control channel (PSCCH) 315, a physical sidelink shared channel (PSSCH) 320, and / or a physical sidelink feedback channel (PSFCH) 325. The PSCCH 315 may be used to communicate control information, similar to a physical downlink control channel (PDCCH) and / or a physical uplink control channel (PUCCH) used for cellular communications with the base station 110 over an access link or access channel. The PSSCH 320 may be used to communicate data, similar to a physical downlink shared channel (PDSCH) and / or a physical uplink shared channel (PUSCH) used for cellular communications with the base station 110 over an access link or access channel. For example, the PSCCH 315 may carry sidelink control information (SCI) 330, which may indicate various control information used for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, spatial resources, etc.), where a transport block (TB) 335 may be carried on the PSSCH 320. The TB 335 may include data. The PSFCH 325 may be used to communicate sidelink feedback 340, such as hybrid automatic repeat request (HARQ) feedback (e.g., positive or negative acknowledgement (ACK / NACK) information), transmit power control (TPC), scheduling request (SR), etc.

[0043] In some aspects, one or more sidelink channels 310 may use a resource pool. For example, a scheduling assignment (e.g., included in the SCI 330) may be transmitted in a subchannel using a particular resource block (RB) over time. In some aspects, a data transmission (e.g., on the PSSCH 320) associated with the scheduling assignment may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and associated data transmission are not transmitted on adjacent RBs.

[0044] In some aspects, the UE 305 may operate using a transmit mode, in which case resource selection and / or scheduling is performed by the UE 305 (e.g., rather than the base station 110). In some aspects, the UE 305 may perform resource selection and / or scheduling by sensing channel availability for transmission. For example, the UE 305 may measure Received Signal Strength Indicator (RSSI) parameters (e.g., Sidelink RSSI (S-RSSI) parameters) associated with various sidelink channels, may measure Reference Signal Received Power (RSRP) parameters (e.g., PSSCH-RSRP parameters) associated with various sidelink channels, may measure Reference Signal Received Quality (RSRQ) parameters (e.g., PSSCH-RSRQ parameters) associated with various sidelink channels, etc., and may select a channel for transmission of a sidelink communication based at least in part on the measurements.

[0045] Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling using the SCI 330 received in the PSCCH 315, which may indicate occupied resources, channel parameters, etc. Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling by determining a channel busy ratio (CBR) associated with various sidelink channels, which may be used for rate control (e.g., by indicating a maximum number of resource blocks the UE 305 may use for a particular set of subframes).

[0046] In a transmission mode in which resource selection and / or scheduling is performed by the UE 305, the UE 305 may generate a sidelink grant and transmit the grant in the SCI 330. The sidelink grant may indicate one or more parameters (e.g., transmission parameters) to be used for the next sidelink transmission, such as, for example, one or more resource blocks to be used for the next sidelink transmission on the PSSCH 320 (e.g., for the TB 335), one or more subframes to be used for the next sidelink transmission, a modulation and coding scheme (MCS) to be used for the next sidelink transmission, etc. In some aspects, the UE 305 may generate a sidelink grant indicating one or more parameters for semi-persistent scheduling (SPS), such as a periodicity of the sidelink transmissions. Additionally or alternatively, the UE 305 may generate a sidelink grant for event-driven scheduling, such as for on-demand sidelink messages.

[0047] As indicated above, Figure 3 is given as an example. Other examples may differ from the example described with respect to Figure 3.

[0048] FIG. 4 is a diagram illustrating example sidelink and access link communications 400 in accordance with various aspects of the present disclosure.

[0049] As shown in FIG. 4, a transmitter (Tx) UE 405 and a receiver (Rx) UE 410 may communicate with each other via a sidelink, as described above in connection with FIG. 3. As further illustrated, in some sidelink modes, the base station 110 may communicate with the Tx UE 405 via a first access link. Additionally or alternatively, in some sidelink modes, the base station 110 may communicate with the Rx UE 410 via a second access link. The Tx UE 405 and / or the Rx UE 410 may correspond to one or more UEs described elsewhere herein, such as the UE 120 of FIG. 1. Thus, a sidelink may refer to a direct link between the UEs 120, and an access link may refer to a direct link between the base station 110 and the UE 120. Sidelink communications may be transmitted via the sidelink, and access link communications may be transmitted via the access link. The access link communication may be either downlink communication (from the base station 110 to the UE 120) or uplink communication (from the UE 120 to the base station 110). In some aspects, the UEs 405 and 410 may not be associated with an access link.

[0050] As indicated above, Figure 4 is given as an example. Other examples may differ from the example described with respect to Figure 4.

[0051] Two nodes may communicate with each other using sidelink communication. The nodes may be any UE, such as an integrated access and backhaul (IAB) node, a UE associated with vehicular communication, a UE associated with a sidelink network, a reduced capability UE, etc. Sidelink communication involves transmission or reception of data between UEs without an intermediate base station or scheduling entity and without communication of data over an access link. Sidelink communication may be useful in various applications, such as low latency scenarios, poor coverage scenarios, relaying from UE to network or network to UE, vehicle-to-anything communication, vehicle-to-vehicle communication, etc. The nodes may use beamforming to communicate with each other on the sidelink, which may improve the wireless performance of the nodes while using less power than omnidirectional or quasi-omnidirectional transmissions with comparable range.

[0052] In some cases, a beam on a beamformed sidelink may fail, meaning that the beam does not provide a link to another node any more. For example, an obstruction may enter the propagation path of the beam, or a node transmitting or receiving the beam may move, thereby causing a sidelink failure. In this case, the beamformed sidelink may undergo performance degradation or may fail. This may lead to communication interruptions, resource waste, reduced throughput, etc. Furthermore, in the absence of a central scheduler associated with the sidelink to arrange the transmission of signals on the sidelink or beam failure recovery, it may be difficult to quickly detect a failing beam on the sidelink.

[0053] Some techniques and apparatus described herein allow a pair of nodes to perform beam failure detection and recovery on a sidelink between the pair of nodes. For example, a pair of nodes associated with a common timing may transmit signals between each other for resource allocations known to the pair of nodes. The pair of nodes may identify a healthy link or a failed beam or link based at least in part on whether a signal is received on the allocated resources, and may perform beam failure recovery (BFR) based at least in part on detecting a failed beam or link. In this manner, the pair of nodes can identify beam failure and perform BFR on the sidelink without the involvement of a central scheduler, such as a gNB. Identifying beam failure and performing BFR on the sidelink without the involvement of a central scheduler can reduce the impact of a blocked beam, thereby improving radio link quality, throughput, and resource utilization, as well as reducing latency and overhead associated with identifying beam or sidelink failures.

[0054] 5-8 illustrate examples 500, 600, 700, and 800 of sidelink beam failure detection and recovery according to various aspects of the present disclosure. The examples 500, 600, 700, and 800 include a first UE 120 and a second UE 120 (e.g., UE 305-1, UE 305-2, UE 405, UE 410, etc.), which are referred to as a first UE and a second UE. In some aspects, the first UE may be a first node and the second UE may be a second node. In some aspects, the first UE and / or the second UE may be associated with an access link to the BS 110. In some aspects, the first UE and the second UE may not be associated with an access link to the BS 110. Although the operations described in Figures 5-8 are described as being performed by a first UE and a second UE, these operations may be performed by other types of wireless nodes (e.g., an IAB node, etc.).

[0055] FIG. 5 illustrates an example 500 of sidelink beam monitoring on an intact sidelink. As illustrated, a first UE may be associated with a transmit (Tx) beam 505 and a receive (Rx) beam 510. A second UE may be associated with an Rx beam 515 corresponding to the Tx beam 505 and a Tx beam 520 corresponding to the Rx beam 510. The Tx beam 505 and the Rx beam 515 may form a beamformed sidelink 525 from the first UE to the second UE, and the Tx beam 520 and the Rx beam 510 may form a beamformed sidelink 530 from the second UE to the first UE. For example, the beamformed sidelinks 525 and 530 may carry the sidelink channel 310 (shown in FIG. 3) between the first UE and the second UE. In some aspects, the first UE and the second UE may be associated with a single beamformed sidelink that may be used for communication in both directions, as shown in FIG.

[0056] As indicated by reference numeral 535, the first UE may transmit a first signal at time T1. For example, the first UE may transmit the first signal on a resource allocation (e.g., a time and / or frequency resource allocation) known to the first UE and the second UE, the resource allocation being associated with time T1. The first UE and the second UE may be associated with a common timing, meaning that the second UE can determine the time T1 at which the UE transmits the first signal. For example, in some aspects, the first UE and the second UE may have a common timing based at least in part on being configured with a common timing by a base station (e.g., via an access link). In some aspects, the first UE and the second UE may have a common timing based at least in part on the positioning systems (e.g., Global Positioning System (GPS), Global Navigation Satellite System (GNSS), etc.) of the first UE and the second UE, respectively. By establishing common timing, the second UE can determine when the first signal is expected (and the first UE can determine when the second signal is expected), thereby enabling sidelink beam monitoring using the first, second, and third signals.

[0057] In some aspects, the first UE and the second UE may determine T1, T2, and / or T3. For example, the first UE and the second UE may communicate with each other to identify (e.g., determine) resource allocations for transmission / reception of the first signal, the second signal, and the third signal, which may eliminate the need for a scheduling entity to be involved, thereby saving computational resources of the scheduling entity. In some aspects, the first UE and the second UE may be configured with information indicating T1, T2, and / or T3. For example, this information may be specified in a wireless telecommunications standard, which may save signaling resources of the UE and the BS 110 associated with the UE. In some aspects, the first UE and the second UE may receive information (e.g., from a scheduling entity such as BS 110) indicating T1, T2, and / or T3, which may conserve resources of the first UE and the second UE that would otherwise be used to determine T1, T2, and / or T3.

[0058] As indicated by reference numeral 540, the second UE may transmit a second signal on the beamformed sidelink 530. For example, the second UE may transmit the second signal at time T2 (e.g., using a resource allocation associated with time T2 and known to the first UE and the second UE) based at least in part on receiving the first signal on a resource allocation associated with time T1. In some aspects, T2 may be offset from T1 by a certain amount of time (e.g., approximately 10 ms, etc.), the offset may be configurable, predefined, negotiated by the first UE and the second UE, etc. As indicated by reference numeral 545, the first UE may transmit a third signal on the beamformed sidelink 525. For example, the first UE may transmit a third signal at time T3 (e.g., using a resource allocation known to the first UE and the second UE and associated with time T3) based at least in part on receiving the second signal on a resource allocation associated with time T2. In some aspects, T3 may be offset from T2 by a fixed amount of time (e.g., approximately 10 ms, etc.), the offset may be configurable, predefined, negotiated by the first UE and the second UE, etc.

[0059] By transmitting the second signal based at least in part on receiving the first signal and the third signal based at least in part on receiving the second signal, the first UE and the second UE may determine whether the beamformed sidelink 525 and the beamformed sidelink 530 have failed. For examples of failures of the beamformed sidelink 525 and / or the beamformed sidelink 530, see Figs. 6-8. The first signal, the second signal, and / or the third signal may include any form of signaling, such as a reference signal (RS) (e.g., Channel State Information (CSI) RS (CSI-RS), Sounding Reference Signal, etc.), a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Feedback Channel (PSFCH), etc. The first signal, the second signal, and the third signal may all be the same type of signal or may include two or more different types of signals.

[0060] Performing sidelink beam failure detection using the first signal, the second signal, and the third signal may involve lower overhead than some other sidelink beam failure detection procedures. For example, in some cases, the first UE may transmit a beacon (e.g., a signal such as a synchronization signal block, etc.) on the beamformed sidelink, and the second UE may report to the base station 110 on whether the beacon is received. The base station 110 may coordinate beam failure recovery when the beacon is not received by the second UE. However, base station coordination of monitoring and beam failure recovery may involve significant overhead and latency and may be difficult or impossible in poor access network coverage scenarios. As another example, in some cases, the first UE may transmit a beacon on the beamformed sidelink, and when the beacon is not received, the second UE may initiate a random access channel (RACH) procedure on the beamformed sidelink. However, the RACH-based sidelink beam failure detection procedure may require the first UE and the second UE to continuously maintain RACH resources, which may be more resource intensive than maintaining resources for the first signal, the second signal, and the third signal.

[0061] FIG. 6 illustrates an example 600 in which a beamformed sidelink from a first UE to a second UE has failed, as indicated by an "X" on the beamformed sidelink from the first UE to the second UE. As indicated by reference numeral 610, the first UE may transmit a first signal at time T1. As indicated by reference numeral 620, the second UE may determine that the first signal is not received within a threshold time of T1. Thus, the second UE may not transmit a second signal, as indicated by reference numeral 630. The first UE may determine that the second signal is not received at time T2, as indicated by reference numeral 640. This may indicate to the first UE that the transmission of the first signal and / or the second signal has failed, meaning that one or more of the beamformed sidelinks between the first UE and the second UE have failed. Thus, as indicated by reference numeral 650, the first UE may not transmit the third signal at time T3.

[0062] As indicated by reference numerals 660 and 670, the first UE and the second UE may perform a sidelink BFR procedure based at least in part on determining that the first signal, the second signal, and / or the third signal are not received. In some aspects, the first UE and the second UE may perform a sidelink BFR procedure based at least in part on determining that the first signal and the second signal are not received, which may reduce latency associated with performing a sidelink BFR procedure as compared to performing a sidelink BFR procedure after determining that the third signal is not received.

[0063] In a sidelink BFR procedure, the first UE may transmit beam failure recovery synchronization signals on multiple Tx beams at predefined time / frequency locations (e.g., resource allocations) known to the first UE and the second UE. The second UE may receive the beam failure recovery synchronization signals on multiple Rx beams. Based at least in part on receiving the beam failure recovery synchronization signals over the multiple Tx-Rx beam combinations, the second UE may determine a best Tx beam to be used by the first UE and a best Rx beam to be used by the second UE for a beamformed sidelink from the first UE to the second UE. The second UE may use this information to transmit a RACH signal to the first UE. For example, the RACH signal may use resources configured as part of the sidelink BFR procedure. The first UE may receive a potential beam failure recovery RACH signal from the second UE at predefined time / frequency locations (e.g., RACH resources) known to both UEs. The second UE may transmit a RACH signal when the first UE is using an Rx beam corresponding to the best Tx beam that the first UE used to transmit the synchronization signal. Upon receiving the RACH signal, the first UE may determine a best Tx beam for a beamformed sidelink from the first UE to the second UE. This sidelink BFR procedure may be initiated (e.g., without base station intervention) based at least in part on failure to detect the first, second, and / or third signals. It should also be noted that the roles of the first UE and the second UE in the sidelink BFR procedure may be reversed (e.g., the first UE may perform the RACH procedure and the second UE may transmit the synchronization signal) to establish a beamformed link from the second UE to the first UE.

[0064] In some aspects, the first UE and / or the second UE may determine beam failure based at least in part on failure to receive a threshold number of signals. For example, the first UE and / or the second UE may declare beam failure upon failure to receive N first / second / third signals or upon determining that the procedure of receiving and transmitting the first / second / third signals has failed N times, where N is an integer. This may save computational and communication resources that would otherwise be used to prematurely trigger a sidelink BFR procedure due to a single failed signal transmission.

[0065] FIG. 7 illustrates an example 700 in which a beamformed sidelink from the second UE to the first UE fails, as indicated by an "X" on the beamformed sidelink from the second UE to the first UE. As indicated by reference numeral 710, the first UE may transmit a first signal at time T1. As indicated by reference numeral 720, the second UE may transmit a second signal at time T2 based at least in part on the successful reception of the first signal at time T1. However, the first UE fails to receive the second signal, as indicated by reference numeral 730. Thus, the first UE determines that a third signal should not be transmitted to the second UE, as indicated by reference numeral 740. The second UE may determine that the third signal is not received at time T3. Thus, the first UE and the second UE may determine that one or more beamformed sidelinks between the second UE and the first UE have failed because the second UE successfully received the first signal and unsuccessfully received the third signal, and because the first UE did not receive the second signal. Thus, as indicated by reference numerals 760 and 770, the first UE and the second UE may perform a sidelink BFR procedure, such as the sidelink BFR procedure described in connection with FIG. 6.

[0066] The case where both beamformed sidelinks fail may be similar to examples 600 and 700, as the first UE and the second UE may determine that the third and second signals should not be transmitted based at least in part on failing to receive the second and first signals, respectively.

[0067] FIG. 8 illustrates an example 800 in which a single beamformed sidelink between the second UE and the first UE is used. For example, the single beamformed sidelink may be a full-duplex sidelink using some form of duplexing or may be used to communicate in both directions. In the example 800, the beamformed sidelink between the second UE and the first UE is not functioning as indicated by an "X" on the beamformed sidelink. Thus, the first signal, indicated by reference numeral 810, is not received by the second UE, indicated by reference numeral 820. Thus, the second UE determines not to transmit the second signal, indicated by reference numeral 830. The first UE may determine that the second signal is not received at time T2, indicated by reference numeral 840, and may determine that the third signal should not be transmitted, indicated by reference numeral 850. As indicated by reference numerals 860 and 870, the first UE and the second UE may perform a sidelink BFR procedure based at least in part on determining that the beamformed sidelink has failed, such as the sidelink BFR procedure described in connection with FIG. 6.

[0068] As noted above, Figures 5-8 are provided as one or more examples. Other examples may differ from what is described with respect to Figures 5-8.

[0069] 9 illustrates an example process 900, performed by, for example, a first node, in accordance with various aspects of the present disclosure. The example process 900 is an example in which a first node (e.g., UE 120, BS 110, UE 305, UE 405, UE 410, first UE 120, etc., in FIGS. 5-8) performs operations associated with sidelink beam failure detection.

[0070] 9, in some aspects, process 900 may include transmitting a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing (block 910). For example, the first node (e.g., using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, antenna 234, etc.) may transmit a first signal to the second node on a beamformed link from the first node to the second node, as described above. In some aspects, the first node and the second node are associated with a common timing.

[0071] 9, in some aspects, process 900 may include determining whether a second signal is received on a beamformed link from the second node to the first node based at least in part on the first signal (block 920). For example, the first node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may determine whether a second signal is received on a beamformed link from the second node to the first node based at least in part on the first signal, as described above.

[0072] 9, in some aspects, process 900 may include transmitting a third signal over the beamformed link from the first node to the second node based at least in part on receiving the second signal (block 930). For example, the first node (e.g., using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antennas 252, controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, antennas 234, etc.) may transmit the third signal based at least in part on receiving the second signal, as described above.

[0073] 9, in some aspects, process 900 may include performing a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received (block 940). For example, the first node (e.g., using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, antennas 234, controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antennas 252, etc.) may perform a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received, as described above.

[0074] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and / or with respect to one or more other processes described elsewhere herein.

[0075] In a first aspect, at least one of the first signal, the second signal, or the third signal includes a channel state information reference signal.

[0076] In a second aspect, alone or in combination with the first aspect, the first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal.

[0077] In a third aspect, alone or in combination with one or more of the first and second aspects, the respective resource allocations are determined by one or more of the first node or the second node.

[0078] In a fourth aspect, either alone or in combination with one or more of the first to third aspects, the respective resource allocation is determined by a base station associated with the first node or the second node.

[0079] In a fifth aspect, either alone or in combination with one or more of the first to fourth aspects, the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link.

[0080] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the common timing is determined based at least in part on base stations associated with the first node and the second node.

[0081] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, the common timing is determined based at least in part on positioning systems of the first node and the second node.

[0082] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a ProSe sidelink interface.

[0083] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, the first node and the second node include user equipment.

[0084] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the first node and the second node comprise integrated access and backhaul nodes.

[0085] In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, performing a sidelink beam failure recovery procedure further includes performing a sidelink beam failure recovery procedure based at least in part on failing to receive the second signal a threshold number of times.

[0086] 9 illustrates example blocks of process 900, in some aspects process 900 may include additional blocks, fewer blocks, different blocks, or blocks ordered differently than the blocks illustrated in FIG 9. Additionally or alternatively, two or more of the blocks of process 900 may be performed in parallel.

[0087] 10 illustrates an example process 1000 performed, for example, by a second node, in accordance with various aspects of the present disclosure. The example process 1000 is an example in which a second node (e.g., UE 120, BS 110, UE 305, UE 405, UE 410, second UE 120, etc., in FIGS. 5-8) performs operations associated with sidelink beam failure detection.

[0088] 10, in some aspects, process 1000 may include determining whether a first signal is received from a first node on a beamformed link from the first node to a second node, where the first node and the second node are associated with a common timing (block 1010). For example, the second node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may determine whether a first signal is received from the first node on a beamformed link from the first node to the second node, as described above. In some aspects, the first node and the second node are associated with a common timing.

[0089] 10, in some aspects, process 1000 may include determining whether to transmit a second signal over a beamformed link from the second node to the first node based at least in part on whether the first signal is received (block 1020). For example, the second node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may determine whether to transmit a second signal over a beamformed link from the second node to the first node based at least in part on whether the first signal is received, as described above.

[0090] 10, in some aspects, process 1000 may include receiving a third signal over the beamformed link from the first node to the second node based at least in part on the second signal (block 1030). For example, the second node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may receive the third signal based at least in part on the second signal, as described above. In some aspects, the second node may receive the third signal after transmitting the second signal.

[0091] 10, in some aspects, the process 1000 may include performing a sidelink beam failure recovery procedure based at least in part on the failure to receive the first signal or the third signal (block 1040). For example, the second node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, controller / processor 280, etc.) may perform the sidelink beam failure recovery procedure based at least in part on the failure to receive the first signal or the third signal, as described above. In some aspects, the second node may perform the sidelink beam failure recovery procedure after determining that the second signal should not be transmitted.

[0092] Process 1000 may include additional aspects, such as any single aspect or any combination of aspects described below and / or with respect to one or more other processes described elsewhere herein.

[0093] In a first aspect, the process 1000 includes transmitting a second signal based at least in part on receiving the first signal.

[0094] In a second aspect, alone or in combination with the first aspect, at least one of the first signal, the second signal, or the third signal includes a channel state information reference signal.

[0095] In a third aspect, alone or in combination with one or more of the first and second aspects, the first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal.

[0096] In a fourth aspect, either alone or in combination with one or more of the first to third aspects, each resource allocation is determined by one or more of the first node or the second node.

[0097] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, the respective resource allocation is determined by a base station associated with the first node or the second node.

[0098] In a sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link.

[0099] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, the common timing is based at least in part on base stations associated with the first node and the second node.

[0100] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the common timing is based at least in part on positioning systems of the first node and the second node.

[0101] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a ProSe sidelink interface.

[0102] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the first node and the second node include user equipment.

[0103] In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, the first node and the second node comprise integrated access and backhaul nodes.

[0104] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, performing a sidelink beam failure recovery procedure further includes performing a sidelink beam failure recovery procedure based at least in part on failing to receive one or more of the first signal or the third signal a threshold number of times.

[0105] 10 illustrates example blocks of process 1000, in some aspects process 1000 may include additional blocks, fewer blocks, different blocks, or blocks ordered differently than the blocks illustrated in FIG 10. Additionally or alternatively, two or more of the blocks of process 1000 may be performed in parallel.

[0106] The following provides a summary of several aspects of the disclosure.

[0107] Aspect 1: A method of wireless communication implemented by a first node, the method including: transmitting a first signal to a second node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determining, based at least in part on the first signal, whether a second signal is received on the beamformed link from the second node to the first node; transmitting a third signal on the beamformed link from the first node to the second node based at least in part on receiving the second signal, or performing a sidelink beam failure recovery procedure based at least in part on determining that the second signal is not received.

[0108] Aspect 2: The method of aspect 1, wherein at least one of the first signal, the second signal, or the third signal includes a channel state information reference signal.

[0109] Aspect 3: The method of any of aspects 1-2, wherein the first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal.

[0110] Aspect 4: The method of aspect 3, wherein the respective resource allocations are determined by one or more of the first node or the second node.

[0111] Aspect 5: The method of aspect 3, wherein the respective resource allocation is determined by a base station associated with the first node or the second node.

[0112] Aspect 6: The method of any of aspects 1 to 5, wherein the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link.

[0113] Aspect 7: The method of any of aspects 1-6, wherein the common timing is determined based at least in part on a base station associated with the first node and the second node.

[0114] Example 8: The method of any of Examples 1-7, wherein the common timing is determined based at least in part on positioning systems of the first node and the second node.

[0115] Aspect 9: The method of any of aspects 1-8, wherein the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a ProSe sidelink interface.

[0116] Example 10: The method of any of Examples 1-9, wherein the first node and the second node include user equipment.

[0117] Example 11: The method of any of Examples 1-9, wherein the first node and the second node include integrated access and backhaul nodes.

[0118] Aspect 12: The method of any of aspects 1-11, wherein the step of performing a sidelink beam failure recovery procedure further includes a step of performing a sidelink beam failure recovery procedure based at least in part on failing to receive the second signal a threshold number of times.

[0119] Aspect 13: A method of wireless communication implemented by a second node, comprising: determining whether a first signal is received from the first node on a beamformed link from the first node to the second node, where the first node and the second node are associated with a common timing; determining whether to transmit a second signal on the beamformed link from the second node to the first node based at least in part on whether the first signal is received; and receiving a third signal based at least in part on the second signal, or performing a sidelink beam failure recovery procedure based at least in part on a failure to receive the first signal or the third signal.

[0120] Aspect 14: The method of aspect 13, further comprising transmitting a second signal based at least in part on receiving the first signal.

[0121] Example 15: The method of any of Examples 13-14, wherein at least one of the first signal, the second signal, or the third signal includes a channel state information reference signal.

[0122] Aspect 16: The method of any of aspects 13-15, wherein the first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal.

[0123] Aspect 17: The method of aspect 16, wherein the respective resource allocations are determined by one or more of the first node or the second node.

[0124] Aspect 18: The method of aspect 16, wherein the respective resource allocation is determined by a base station associated with the first node or the second node.

[0125] Aspect 19: The method of any of aspects 13 to 18, wherein the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link.

[0126] Example 20: The method of any of Examples 13-19, wherein the common timing is based at least in part on a base station associated with the first node and the second node.

[0127] Example 21: The method of any of Examples 13-20, wherein the common timing is based at least in part on positioning systems of the first node and the second node.

[0128] Aspect 22: The method of any of aspects 13-21, wherein the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a ProSe sidelink interface.

[0129] Example 23: The method of any of Examples 13-22, wherein the first node and the second node include user equipment.

[0130] Example 24: The method of any of Examples 13-22, wherein the first node and the second node include integrated access and backhaul nodes.

[0131] Aspect 25: The method of any of aspects 13-24, wherein the step of performing a sidelink beam failure recovery procedure further includes a step of performing a sidelink beam failure recovery procedure based at least in part on failing to receive one or more of the first signal or the third signal a threshold number of times.

[0132] Aspect 26: An apparatus for wireless communication in a device, comprising a processor, a memory coupled to the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of one or more of aspects 1 to 25.

[0133] Aspect 27: A device for wireless communication comprising a memory and one or more processors coupled to the memory, wherein the memory or the one or more processors are configured to implement a method of one or more of aspects 1 to 25.

[0134] Example 28: An apparatus for wireless communication, comprising at least one means for performing the method of one or more of Examples 1 to 25.

[0135] Aspect 29: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform a method of one or more of aspects 1 to 25.

[0136] Aspect 30: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions including one or more instructions that, when executed by one or more processors of a device, cause the device to perform a method of one or more of aspects 1-25.

[0137] The above disclosure provides illustration and description, and is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments.

[0138] As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, and / or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0139] As used herein, "meeting a threshold" can refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc., depending on the context.

[0140] It will be apparent that the systems and / or methods described herein may be implemented in various forms of hardware, firmware, and / or a combination of hardware and software. The actual dedicated control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods have been described herein without reference to any specific software code. It should be understood that software and hardware may be designed to implement the systems and / or methods based at least in part on the description herein.

[0141] Although certain combinations of features are recited in the claims and / or disclosed herein, these combinations do not limit the disclosure of the various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed herein. Although each dependent claim listed below may directly depend on only one claim, the disclosure of the various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to a list of "at least one of" items refers to any combination of those items, including single members. By way of example, "at least one of a, b, or c" is intended to include a, b, c, ab, ac, bc, and abc, as well as combinations having multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0142] No element, act, or instruction used herein should be construed as critical or essential unless expressly described as such. Also, as used herein, the articles "a" and "an" are intended to include one or more items and may be used interchangeably with "one or more." Additionally, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and may be used interchangeably with "one or more." When only one item is intended, the phrase "only one" or similar language is used. Also, as used herein, terms such as "has," "having," and the like are intended to be open-ended terms. Additionally, the phrase "based on" is intended to mean "based at least in part on" unless expressly specified otherwise. [Explanation of symbols]

[0143] 100 Wireless Network 110 BS, base station 110a BS, Macro BS 110b BS 110c BS 110d BS, live BS 120UE 120b UE 120c UE 120d UE 120e UE 130 Network Controller 212 Data Source 220 Transmit Processor 230 Transmit (TX) Multiple Input Multiple Output (MIMO) Processor 232 Modulator (MOD), Demodulator 234 Antenna 236 MIMO Detector 238 Receive Processor 239 Data Sink 240 Controllers / Processors 242 Memory 244 Communication Unit 246 Scheduler 252 Antenna 254 Demodulator (DEMOD), Modulator 256 MIMO detector 258 Receive Processor 260 Data Sink 262 Data Sources 264 Transmit Processor 266 TX MIMO Processor 280 Controller / Processor 282 Memory 290 Controller / Processor 292 Memory 294 Communication Unit 305 UE 310 Sidelink Channel 315 Physical Sidelink Control Channel (PSCCH) 320 Physical Sidelink Shared Channel (PSSCH) 325 Physical Sidelink Feedback Channel (PSFCH) 405 Transmitter (Tx) UE, UE 410 Receiver (Rx) UE, UE 525 Side Link 530 Side Link

Claims

1. A first node for wireless communication, comprising: Memory, and one or more processors operably coupled to the memory, the one or more processors comprising: transmitting a first signal to the second node on a beamformed link from the first node to the second node; the first node and the second node are associated with a common timing; and determining, based on the first signal, whether a second signal is received on a beamformed link from the second node to the first node; transmitting a third signal on the beamformed link from the first node to the second node if the second signal is received; and performing a sidelink beam failure recovery procedure if the second signal is not received. configured to: The first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal. The first node.

2. At least one of the first signal, the second signal, or the third signal includes a channel state information reference signal; or The one or more processors are configured, when performing the sidelink beam failure recovery procedure, to perform the sidelink beam failure recovery procedure based on a threshold number of failures to receive the second signal. The first node according to claim 1.

3. the respective resource allocations are determined by one or more of the first node or the second node; or The respective resource allocation is determined by a base station associated with the first node or the second node. The first node according to claim 1.

4. the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link; or The beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a PC5 sidelink interface. The first node according to claim 1.

5. the common timing is determined based on a base station associated with the first node and the second node; or The common timing is determined based on positioning systems of the first node and the second node. The first node according to claim 1.

6. the first node and the second node comprise user equipment; or The first node and the second node include integrated access and backhaul nodes. The first node according to claim 1.

7. A second node for wireless communication, comprising: Memory, and one or more processors operably coupled to the memory, the one or more processors comprising: determining whether a first signal is received from a first node on a beamformed link from the first node to the second node; the first node and the second node are associated with a common timing; and determining whether to transmit a second signal on a beamformed link from the second node to the first node based on whether the first signal is received; and If the second signal is transmitted, determining whether a third signal is received based on the second signal; performing a sidelink beam failure recovery procedure if the first signal or the third signal is not received; The first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal. The second node.

8. the one or more processors are further configured to transmit the second signal based on receiving the first signal; or When the one or more processors perform the sidelink beam failure recovery procedure, configured to perform the sidelink beam failure recovery procedure based on a threshold number of failures to receive one or more of the first signal or the third signal. The second node according to claim 7.

9. the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link; or the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a PC5 sidelink interface; The second node according to claim 7.

10. 1. A method of wireless communication implemented by a first node, comprising: transmitting a first signal to a second node on a beamformed link from the first node to the second node, the first node and the second node are associated with a common timing; determining, based on the first signal, whether a second signal is received on a beamformed link from the second node to the first node; if the second signal is received, transmitting a third signal on the beamformed link from the first node to the second node; and performing a sidelink beam failure recovery procedure if the second signal is not received; The first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal. method.

11. At least one of the first signal, the second signal, or the third signal includes a channel state information reference signal; or The step of performing the sidelink beam failure recovery procedure further includes the step of performing the sidelink beam failure recovery procedure based on a threshold number of failures to receive the second signal. The method of claim 10.

12. the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link; or The beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a PC5 sidelink interface. The method of claim 10.

13. A method of wireless communication implemented by a second node, comprising: determining whether a first signal is received from a first node on a beamformed link from the first node to the second node, the first node and the second node are associated with a common timing; determining whether to transmit a second signal on a beamformed link from the second node to the first node based on whether the first signal is received; If the second signal is transmitted, determining whether a third signal is received based on the second signal; and performing a sidelink beam failure recovery procedure if the first signal or the third signal is not received; The first signal, the second signal, and the third signal are associated with respective resource allocations that are known to the first node and the second node prior to transmission of the first signal. method.

14. transmitting the second signal based on receiving the first signal; or The step of performing a sidelink beam failure recovery procedure includes: and performing the sidelink beam failure recovery procedure based on a threshold number of failed attempts to receive the second signal. The method of claim 13.

15. the beamformed link from the first node to the second node and the beamformed link from the second node to the first node are the same link; or The beamformed link from the first node to the second node and the beamformed link from the second node to the first node are associated with a PC5 sidelink interface. The method of claim 13.

Images