Procedures and methods of initial beam pairing during unicast link establishment

Abstract

Techniques described herein include solutions for beam pairing in sidelink. A first user equipment (UE) may transmit one or more direct connection request (DCR) messages to a second UE using one or more respective transmit (Tx) beams. The first UE may additionally transmit one or more reference signals to the second UE using the one or more respective Tx beams. The second UE may receive and measure the one or more reference signals, and evaluate a beam reporting condition one or more times based on the measurements. Each time the beam reporting condition is satisfied, the second UE transmits a beam reporting message to the first UE. The beam reporting message(s) may be received by the first UE, and the first UE may determine an optimal Tx beam for serving the second UE based on the beam reporting messages.

Description

PROCEDURES AND METHODS OF INITIAL BEAM PAIRING DURING UNICAST LINK ESTABLISHMENTREFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of U.S. Provisional Application No.63 / 519,138, filed on August 11 , 2023, the contents of which are hereby incorporated by reference in their entiretyFIELD

[0002] The present disclosure relates to wireless communication networks including techniques for beam pairing within wireless networks.BACKGROUND

[0003] Wireless communication networks may include user equipments (UEs), base stations, and / or other types of wireless devices capable of communicating with one another. During operation, the UEs may communicate with one another via sidelink signaling.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The following detailed description refers to the accompanying drawings. Like reference numbers in different drawings may identify the same or similar features, elements, operations, etc. Additionally, the present disclosure is not limited to the following description as other implementations may be utilized, and structural or logical changes made, without departing from the scope of the present disclosure.

[0005] FIG. 1 is a schematic diagram illustrating signaling between a first user equipment (UE) and a second UE performing a beam pairing procedure in accordance with some aspects of the present disclosure.

[0006] FIG. 2 is a schematic diagram illustrating signaling between a first UE and a second UE including beam reporting message(s) transmitted on a physical sidelink feedback channel (PSFCH) during a beam pairing procedure in accordance with some aspects of the present disclosure.

[0007] FIGS. 3A-3B are schematic diagrams illustrating beam reporting configurations in accordance with some aspects of the present disclosure.

[0008] FIG. 4 is a schematic diagram illustrating a codebook mapping in accordance with some aspects of the present disclosure.

[0009] FIG. 5 is a schematic diagram illustrating signaling between a first UE and a second UE including beam reporting message(s) transmitted using dedicated slots for beam reporting within a resource pool during a beam pairing procedure in accordance with some aspects of the present disclosure.

[0010] FIGS. 6A-6B are schematic diagrams illustrating beam reporting configurations in accordance with some aspects of the present disclosure.

[0011] FIG. 7 is a schematic diagram illustrating signaling between a first UE and a second UE including beam reporting message(s) transmitted using dedicated slots for beam reporting within a resource pool during a beam pairing procedure in accordance with some aspects of the present disclosure.

[0012] FIGS. 8A-8C are schematic diagrams illustrating beam reporting configurations in accordance with some aspects of the present disclosure.

[0013] FIGS. 9-10 are flow diagrams for UEs performing a beam pairing procedure in accordance with some aspects of the present disclosure.

[0014] FIG. 11 is a block diagram illustrating a wireless network including a UE in accordance with some aspects of the present disclosure.

[0015] FIG. 12 is a block diagram illustrating a device that can be employed to perform a sidelink beam pairing procedure in accordance with some aspects of the present disclosure.DETAILED DESCRIPTION

[0016] The following detailed description refers to the accompanying drawings. Like reference numbers in different drawings may identify the same or similar features, elements, operations, etc. Additionally, the present disclosure is not limited to the following description as other implementations may be utilized, and structural or logical changes made, without departing from the scope of the present disclosure.

[0017] Within a wireless network, a user equipment (UE) may communicate with other UEs using sidelink signaling. The UEs may operate in mode 1 or mode 2 sidelink. In mode 1 sidelink, resource allocation (e.g., “scheduling”) is centrally performed by a network, for example, via signaling from a base station of the network. In mode 2 sidelink, resource allocation is performed by the UEs operating in SL, and no central scheduling is used. In order to operate in mode 2 sidelink, the UEs may be preconfigured with one or more sidelink resource pools. A UE may select time frequency resources within a sidelink resource pool to be used for sidelink data transmission. For example, the UE may transmit sidelink control information (SCI) indicating timefrequency resources within a resource pool to be used for a data transmission, and subsequently transmit the data using the indicated time frequency resources.

[0018] In order to improve sidelink performance, beamforming may be used. Beamforming is a process that enables a signal to be transmitted or received in a particular spatial direction. In transmit (Tx) beamforming, the signal may be transmitted with a different amplitude and / or phase using multiple antenna elements simultaneously, causing constructive / destructive interference to occur. As a result of the constructive / destructive interference, the transmitted signal exhibits a stronger signal strength in a certain direction, thereby forming a “beam”. Similarly, in receive beamforming, a signal may be received using multiple antenna elements simultaneously. The multiple antenna elements may be tuned such that signals from a certain direction (e.g., a direction of the “beam”) are received with a higher signal strength.

[0019] A first UE and a second UE may communicate with one another in sidelink using beamforming. By utilizing beamforming, signal transmissions can be spatially concentrated between the first and second UEs. As a result, the signal strength between the first and second UEs is increased, and the interference caused to other UEs operating in sidelink is minimized, thereby improving sidelink performance. In order to utilize beamforming, a beam pair should first be acquired between the first and second UEs. The present disclosure provides techniques and signaling for beam pairing in sidelink.

[0020] FIG. 1 illustrates an example of a first UE 101-1 and a second UE 101 -2 performing a sidelink beam pairing procedure 100 in accordance with some aspects of the present disclosure. The process of FIG. 1 may be performed, for example, when the UE 101 -1 wishes to establish a unicast connection or beam pair with the UE 101 -2.

[0021] At act 1 10, the UE 101 -1 transmits a one or more of direct connection request (OCR) messages using one or more Tx beams 103 respectively. In the example of FIG. 1 , the one or more Tx beams 103 includes a first Tx beam 103A, a second Tx beam 103B, and a third Tx beam 103C. However, in alternative examples, the one or more Tx beams 103 may include more or fewer beams.

[0022] The one or more DOR messages may indicate an intention of the UE 101 -1 to establish a unicast connection or beam pair with the UE 101 -2. For example, a DCR message may include a source identity (ID) and / or a destination ID. The source ID may correspond to the UE 101 -1 and the destination ID may correspond to the UE 101 -2. By including the source ID and destination ID, the UE 101 -2 can determine that the UE101-1 wishes to establish a unicast connection (e.g., from the source ID), and that the UE 101 -2 is the intended recipient of the DCR message (e.g., from the destination ID).

[0023] In addition to the DCR messages, the UE 101 -1 transmits one or more reference signals using the one or more Tx beams 103 respectively. The reference signals may include, for example, physical sidelink control channel (PSCCH) demodulation reference signal (DMRS), physical sidelink shared channel (PSSCH) DMRS, sidelink channel state information reference signal (CSI-RS), or sidelink synchronization signal block (S-SSB) signals.

[0024] At act 120, the UE 101 -2 transmits a beam reporting message to the UE 101 - 1 in response to a beam reporting condition being satisfied. In some aspects, evaluating the beam reporting condition includes measuring the one or more reference signals. For example, the UE 101-2 performs measurements on each of the one or more reference signals, and determines whether the beam reporting condition is satisfied for each reference signal based on the performed measurement. The measurements may include reference signal received power (RSRP) measurements, or another suitable type of measurement.

[0025] In some aspects, the beam reporting condition includes an RSRP measurement of a reference signal exceeding an RSRP threshold value. For example, the RSRP threshold value may be a (pre)configured threshold value (e.g., configured by a resource pool (pre)configuration), and the UE 101 -2 may transmit a beam reporting message for each reference signal having an RSRP measurement exceeding the (pre)configured threshold value. In some examples, the beam reporting message includes an indication of the RSRP measurement value. As used herein, the term (pre)configuration, (pre)configured, etc. refers to a configuration that may include a preconfiguration, or a dynamic configuration. A pre-configuration, for example, may be specified by a standard such as 2nd generation (2G), 3rd generation (3G), 4th generation (4G), and / or 5th generation (5G) communication standards of the 3rdGeneration Partnership Project (3GPP) standard and stored on a UE or another storage medium. A dynamic configuration may be configured at runtime, for example, the UE may receive a dynamic configuration from a base station.

[0026] In some alternative aspects, the beam reporting condition includes an RSRP measurement of a reference signal exceeding the RSRP measurements of all previously received reference signals of the one or more reference signals. For example, the UE 101-2 transmits a beam reporting message each time a reference signal is received with a new highest RSRP measurement. In some examples, the UEsets an RSRP threshold value equal to an RSRP of the first received reference signal. Each time the RSRP threshold value is exceeded by the RSRP of a subsequent reference signal, the beam reporting condition is satisfied and the RSRP threshold value is updated and set to the new highest RSRP.

[0027] Each beam reporting message may be transmitted in response to a DCR message. In some aspects, the UE 101 -2 determines its Tx beam for transmission of a beam reporting message based on an Rx beam used for reception of the corresponding DCR message. For example, the Tx beam may be the same as the Rx beam (e.g., by beam correspondence) or derived from the Rx beam. If the Tx beam is the same as the Rx beam, the Tx beam may be a wider beam that covers the Rx beam.

[0028] At act 130, the UE 101 -2 determines its optimal Tx beam and Rx beams for communication with the UE 101-1 . In some aspects, the UE 101 -2 sweeps its own Rx beam during reception of the one or more reference signals, and identifies the optimal Rx beam as the one resulting in the highest RSRP.

[0029] Subsequently, the UE 101-2 may determine the optimal Tx beam based on the optimal Rx beam. The optimal Tx beam may be the same as the optimal Rx beam (e.g., by beam correspondence), or derived from the optimal Rx beam (e.g., a wider beam covering the optimal Rx beam).

[0030] At act 140, the UE 101 -1 determines its optimal Tx and Rx beams for communication with the UE 101-2 based on the beam reporting messages received from the UE 101 -2.

[0031] If the beam reporting condition is an RSRP measurement of a reference signal exceeding a (pre)configured threshold value, the UE 101-1 may determine the optimal Tx beam based on the beam reporting message with the highest RSRP measurement value. For example, the UE 101 -1 may determine that the Tx beam corresponding to the beam reporting message with the highest RSRP measurement value is the optimal Tx beam.

[0032] If the beam reporting condition is an RSRP measurement of a reference signal exceeding the RSRP measurements of all previous received reference signals, the UE 101 -1 may determine the optimal Tx beam based on the latest received beam reporting message. For example, the UE 101 -1 may determine that the Tx beam corresponding to the latest received beam reporting message is the optimal Tx beam.

[0033] Subsequently, the UE 101-1 may determine the optimal Rx beam based on the optimal Tx beam. The optimal Rx beam may be the same as the optimal Tx beam(e.g., by beam correspondence, or derived from the optimal Tx beam (e.g., a wider beam covering the optimal Tx beam).

[0034] At act 150, the UE 101 -1 and the UE 101 -2 establish a unicast connection using their optimal Tx / Rx beams.

[0035] FIG. 2 illustrates an example of a first UE 101-1 and a second UE 101-2 performing a sidelink beam pairing procedure 200 in accordance with some aspects of the present disclosure. In some aspects, the beam pairing procedure 200 represents a variation of the beam pairing procedure 100, where the UE 101 -2 performs the beam reporting using a PSFCH.

[0036] At act 210, the UE 101-1 transmits one or more PSCCH transmissions using one or more Tx beams respectively. The one or more Tx beams may be, for example, the one or more Tx beams 103 as described with reference to FIG. 1 . Each PSCCH transmission may indicate resources to be used for a subsequent transmission of a DCR message. In some examples, a PSCCH transmission carries SCI, and the SCI indicates the resources to be used for the DCR message. In some examples, each PSCCH transmission includes PSCCH DMRS, which may be used by the UE 101 -2 to perform channel estimation and demodulate the PSCCH.

[0037] At act 220, the UE 101-1 transmits one or more PSSCH transmissions using the one or more Tx beams respectively. Each PSSCH transmission may include, for example, a DCR message. The DCR message may indicate an intention of the UE 101 -1 to establish a unicast connection or beam pair with the UE 101 -2. In some examples, each PSSCH transmission includes PSSCH DMRS, which may be used by the UE 101 -2 to perform channel estimation and demodulate the PSSCH.

[0038] At act 230, the UE 101 -2 may optionally transmit one or more acknowledgement (ACK) I negative acknowledgement (NACK) message to the UE 101 - 1 in response to one or more of the DCR messages. For example, the UE 101 -2 may indicate ACK for DCR messages that are successfully decoded, or NACK for DCR messages that are not successfully decoded. An ACK / NACK message may be transmitted, for example, on a PSFCH. In some aspects, the UE 101 -2 only transmits ACK / NACK if required. For example, ACK / NACK may be enabled or disabled by control signaling (e.g., SCI).

[0039] At act 240, the UE 101-2 transmits one or more beam reporting messages to the UE 101 -1 on the PSFCH. The PSFCH may be, for example, PSFCH format 0. In some examples, a beam reporting message has a duration of 2 symbols in the time domain. The UE 101 -1 may transmit the beam reporting message in response to abeam reporting condition being satisfied, as previously described.

[0040] At act 250, the UE 101 -2 determines its optimal Tx and Rx beams for communication with the UE 101-1. For example, the UE 101 -2 may sweep its own Rx beam during reception of the DMRS or other reference signal, and identify the optimal beam as the one resulting in the highest measured RSRP of the DMRS or other reference signal. Further, the UE 101 -2 may determine its optimal Tx beam based on the optimal Rx beam. For example, the UE 101-2 may determine that the optimal Tx beam is the same as the optimal Rx beam (e.g., by beam correspondence) or derived from the optimal Rx beam (e.g., a wider beam covering the optimal Rx beam).

[0041] At act 260, the UE 101-1 determines its optimal Tx and Rx beams for communication with the UE 101-2 based on the one or more beam reporting messages. For example, the UE 101 -1 may determine its optimal Tx beam based on the beam reporting message with the highest RSRP value or based on the latest received beam reporting message, depending on which beam reporting condition is used, as previously described. Further, the UE 101 -1 may determine the optimal Rx beam based on the optimal Tx beam. For example, the UE 101 -1 may determine that the optimal Rx beam is the same as the optimal Tx beam (e.g., by beam correspondence) or derived from the optimal Tx beam (e.g., a wider beam covering the optimal Tx beam).

[0042] At act 270, the UE 101 -1 and the UE 101 -2 establish a unicast link using the optimal Tx / Rx beams for the UEs 101 -1 , 101 -2, for example, as described with reference to act 150 of FIG. 1 .

[0043] FIGS. 3A-3B illustrate example beam reporting configurations 300A, 300B in accordance with some aspects of the present disclosure. In some aspects, the UE 101 - 1 transmits one or more DOR messages using one or more Tx beams. After transmitting each of the one or more DCR messages, the UE 101 -1 may monitor a PSFCH for an ACK / NACK message and / or a beam reporting message.

[0044] In the examples of FIGS. 3A-3B, the UE 101 -1 is configured with Tx beams 103A, 103B, 103C (e.g., the one or more Tx beams 103 of FIG. 1 ). Further, the UE 101 - 1 is configured with Rx beams 303A, 303B, 303C associated with the Tx beams 103A, 103B, 103C respectively. As shown, each of the Rx beams may be pointed in a same direction as the associated Tx beam. For example, each Rx beam may be the same as the associated Tx beam (e.g., by beam correspondence) or derived from the corresponding Tx beam (e.g., a wider beam covering the associated Tx beam).

[0045] The UE 101-1 transmits a DCR message 302A using the Tx beam 103A at a first point in time. Subsequently, the UE 101 -1 transmits a DCR message 302B usingthe Tx beam 103B at a second point in time, and transmits a DCR message 302C using the Tx beam 103C at a third point in time. In some examples, one or more of the DCR messages 302A, 302B, 302C are received by the UE 101 -2. The DCR messages 302A, 302B, 302C may indicate an intention of the UE 101 -1 to establish a unicast connection with the UE 101-2. For example, the DCR messages 302A, 302B, 302C include a source ID and / or a destination ID. The source ID may correspond to the UE 101 -1 , and the destination ID may correspond to the UE 101 -2.

[0046] In some aspects, transmission of a DCR message includes a PSCCH transmission followed by a PSSCH transmission, as previously described. For example, the PSCCH transmission carries SCI indicating resources to be used by the PSSCH transmission. Subsequently, the PSSCH is transmitted using the indicated resources. In some examples, the PSSCH carries the DCR message. The PSCCH and PSSCH may include PSCCH DMRS and PSSCH DMRS respectively.

[0047] After transmitting a DCR message (e.g., 302A, 302B, or 302C), the UE 101 -1 monitors a PSFCH for a response from the UE 101 -2. For example, the UE 101 -1 monitors the PSFCH for an ACK / NACK message and / or a beam reporting message. In some aspects, the UE 101 -2 measures DMRS in order to determine whether beam reporting should be performed. For example, the UE 101 -2 measures RSRP of the DMRS of the PSCCH and / or PSSCH of a first DCR message. The measured RSRP value is evaluated according to a beam reporting condition in order to determine if beam reporting should be performed. In some aspects, the beam reporting condition includes the PSCCH and / or the PSSCH associated with the first DCR message being successfully decoded. Additionally or alternatively, the beam reporting condition includes the UE 101 -2 having an interest in establishing a unicast connection with the UE 101 -1 , the source ID matching the UE 101 -1 , and / or the destination ID matching the UE 101 -2. In some examples, the UE 101 -2 determines its interest in establishing the unicast connection with the UE 101 -1 by evaluating the source ID (e.g., of the UE 101 - 1 ) and the destination ID (e.g., of the UE 101 -2) according to a whitelist. The whitelist may be provided by a layer such as a vehicle to everything (V2X) layer or an application layer of the UE 101-2.

[0048] In some aspects, the beam reporting configurations 300A, 300B correspond to the beam pairing procedure 200 of FIG. 2 when using different beam reporting conditions. For example, in FIG. 6A, the beam reporting condition additionally or alternatively includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding a (pre)configured threshold value. Further, in FIG. 6B, the beam reportingcondition additionally or alternatively includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding the RSRP measurements of all previously received reference signals associated with a same DCR message. For example, the DCR messages 302A, 302B, 302C may be considered as a “same” DCR message transmitted on different beams. The DCR messages 302A, 302B, 302C may collectively be referred to as “DCR message 302”.

[0049] As shown in FIG. 3A, the UE 101 -1 transmits the DCR message 302A using the Tx beam 103A. Subsequently, the UE 101 -1 monitors for ACK / NACK and beam reporting using the Rx beam 303A. In the illustrated example, the UE 101 -2 transmits an ACK / NACK message 304A, which is received by the UE 101 -1 using the Rx beam 303A. The ACK / NACK message 304A may indicate ACK if the DCR message 302A was successfully decoded by the UE 101 -2, or NACK if the DCR message 302A was not successfully decoded by the UE 101-2. In the illustrated example, the RSRP measurement of DMRS associated with the DCR message 302A does not exceed the (pre)configured threshold value, such that the beam reporting condition is not satisfied. As a result, no beam reporting message is transmitted by the UE 101 -2 in response to the DCR message 302A.

[0050] Subsequently, the UE 101-1 transmits the DCR message 302B, and monitors for ACK / NACK and beam reporting using the Rx beam 303B. The UE 101-2 transmits an ACK / NACK message 304B and a beam reporting message 306B, which are received by the UE 101 -1 using the Rx beam 303B. In some examples, the DCR message 302B is successfully decoded, and the ACK / NACK message 304B indicates ACK. Further, in some examples, the RSRP measurement of DMRS associated with the DCR message 302B is greater than the (pre)configured threshold value, such that the beam reporting condition is satisfied. In response to the beam reporting condition being satisfied, the UE 101 -2 transmits the beam reporting message 306B. In the example of FIG. 3A, the beam reporting message 306B may indicate the measured RSRP of the DMRS.

[0051] Subsequently, the UE 101-1 transmits the DCR message 302C, and monitors for ACK / NACK and beam reporting using the Rx beam 303C. In the illustrated example, the DCR message 302C is not received by the UE 101 -2, and therefore no ACK / NACK is performed by the UE 101 -2. Furthermore, since the DCR message 302C is not received by the UE 101 -2, no beam reporting is performed. The DCR message 302C may not be received by the UE 101 -2, for example, due to the Tx beam 103C being poorly aligned with the UE 101 -2.

[0052] Based on the beam reporting message(s) received from the UE 101 -2, the UE 101 -1 determines that the Tx beam 103B is the optimal beam for serving the UE 101 -2. In some aspects, the Tx beam corresponding to the beam reporting message with the highest indicated RSRP value is determined to be the optimal beam. Although only 3 beams 103A, 103B, 103C and a single beam reporting message 306B are illustrated in the example of FIG. 3A, similar logic can be extended to scenarios with more beams and / or beam reporting messages.

[0053] As shown in FIG. 3B, similar to FIG. 3A, the UE 101 -1 transmits the DCR message 302A, which is received by the UE 101 -2. In response, the UE 101 -2 transmits the ACK / NACK message 304A, which is received by the UE 101 -1 . As previously mentioned, the beam reporting condition of FIG. 3B includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding the RSRP measurements of all previously received reference signals associated with a same DCR message, which differs from the beam reporting condition of FIG. 3A. As a result, the UE 101 -2 transmits a beam reporting message 306A in response to the DCR message 302A, which is received by the UE 101 -1 using the Rx beam 303A. In the example of FIG. 3B, the DCR message 302A is the first received DCR message. Therefore, the RSRP of DMRS associated with the DCR message 302A exceeds all previous DMRS RSRP measurements, and the beam reporting condition is satisfied. In response to the beam reporting condition being satisfied, the UE 101 -2 transmits the beam reporting message 306A.

[0054] Further, in the example of FIG. 3B, the measured RSRP of DMRS associated with the DCR message 302B is higher than the measured RSRP of DMRS associated with the DCR message 302A. Again, the beam reporting condition is satisfied. In response, the UE 101 -2 transmits the beam reporting message 306B.

[0055] Based on the beam reporting message(s), the UE 101 -1 determines that the Tx beam 103B is the optimal beam for serving the UE 101 -2. In some aspects, the Tx beam corresponding to the most recently received beam reporting message is determined to be the optimal beam. Since the beam reporting condition includes the measured RSRP being greater than all previously measured RSRPs, the latest received beam reporting message corresponds to the highest RSRP value. In some aspects, in the example of FIG. 3B, the beam reporting messages do not include an explicit indication of the measured RSRP, since the Tx beam with the highest RSRP may be determined implicitly by the latest received beam reporting message.

[0056] In some aspects, the UE 101 -2 performs Rx beam sweeping during reception of one or more DCR messages. For example, in FIG. 3A or FIG. 3B, the UE 101 -2 mayreceive a first DCR message 302 of the one or more DCR messages and measure the associated PSCCH DMRS and / or PSSCH DMRS using a first Rx beam. The process may be repeated for a second DCR message using a second Rx beam, a third DCR message using a third Rx beam, etc. Then, the UE 101-2 may identify its optimal Rx beam for communication with the UE 101 -1 based on the Rx beam sweeping performed during the reception of the one or more DCR messages. In the examples of FIGS. 3A- 3B, the UE 101 -1 may determine its optimal Rx beam based on a measurement of DMRS (e.g., PSCCH DMRS and / or PSSCH DMRS) associated with the DCR message 302B. For example, the optimal Rx beam may be determined as the Rx beam resulting in the highest measured RSRP value. Since the DCR message 302B corresponds to the Tx beam 103B (e.g., the optimal Tx beam of the UE 101 -1 ), the Rx beam used to measure the DMRS associated with the DCR message 302B can be used to establish the optimal beam pair with the UE 101 -1. The UE 101 -1 may determine its optimal Rx beam based on its optimal Tx beam, and the UE 101-2 may determine its optimal Tx beam based on its optimal Rx beam, as previously described.

[0057] In some aspects, the UE 101 -2 transmits (and the UE 101-1 monitors for) a beam reporting message (e.g., 306B) in a same slot as the corresponding ACK / NACK message (e.g., 304B). Alternatively, the UE 101 -2 transmits (and the UE 101 -1 monitors for) the beam reporting message using a (pre)configured gap (e.g., a time offset) between the PSCCH and / or PSSCH transmissions associated with the DCR message. For example, the (pre)configured gap may be larger than a gap between PSCCH / PSSCH and ACK / NACK, which may range from 2 to 3 slots. Using the (pre)configured gap may allow the UE 101-2 more time to process the DCR message when compared to the same slot scenario. When using the (pre)configured gap, since the beam reporting message is transmitted in a later slot than ACK / NACK, the UE 101 -2 may use the extra slots to perform higher layer processing of the DCR message.

[0058] FIG. 4 is a schematic diagram illustrating an example codebook mapping 400 in accordance with some aspects of the present disclosure. In some aspects, the codebook mapping 400 is used to communicate an RSRP value in a beam reporting message, for example, the beam reporting message 306B of FIG. 3A.

[0059] As shown, the codebook mapping 400 includes a mapping between an RSRP measurement 402 and a subset of resources 404. In some aspects, the resources 404 include frequency and / or code resources. In the example of FIG. 4, the resources 404 include a plurality of physical resource blocks (PRBs) (e.g., frequency resources) and cyclic shift pairs (e.g., code resources). In some aspects, a PRB comprises 12consecutive subcarriers in the frequency domain. A bandwidth part (BWP) may be divided into multiple PRBs, and the PRBs may be numbered in ascending order starting from 0 at the lower frequency of the BWP. In some aspects, the resources 404 comprise cyclic shift pair mo = 0, with ACK and NACK being represented by mcs = 6, mCs = 0.

[0060] The RSRP measurement 402 may be mapped to a subset of the resources 404 according to the codebook mapping 400 based on a value of the RSRP measurement 402. As shown, the codebook mapping 400 includes the resources 404 arranged in a PRB first, cyclic shift pair second manner. The resources 404 are labeled 1 -12, with the numbering increasing firstly with PRBs and secondly with cyclic shift pairs. In some aspects, the increasing numbering of the resources 404 corresponds to increasing RSRP values. For example, resource 1 of the resources 404 are mapped to a minimum RSRP value, and resource 12 of the resources 404 are mapped to a maximum RSRP value. Resources between 1 and 12 may be mapped to RSRP values between the minimum RSRP value and the maximum RSRP value linearly, logarithmically, or in another suitable manner. Although not shown, in alternative examples, the resources 404 are arranged / numbered in a cyclic shift first, PRB second manner.

[0061] In order to indicate the RSRP value, a beam reporting message (e.g., the beam reporting message 306B of FIG. 3A) may be transmitted using the subset of resources indicated by the codebook mapping 400. For example, based on a specific RSRP value that the UE 101 -2 wishes to indicate, the UE 101 -2 transmits the beam reporting message using specific frequency / code resources according to the codebook mapping 400. In the example of FIG. 4, a specific PRB and cyclic shift pair may be used according to the codebook mapping 400. The codebook mapping 400 may be known by both the UE transmitting (e.g., the UE 101 -2) and the UE receiving (e.g., the UE 101 -1 ) the beam reporting message. The UE receiving the beam reporting message can derive the RSRP value based on a mutual understanding of the codebook mapping 400 and the PRB and cyclic shift pair used to transmit the beam reporting message.

[0062] In some aspects, the PRBs within the resources 404 are distinct from PRBs used for ACK / NACK and / or inter-UE coordination (IUC). By using separate PRBs (e.g., frequency resources) for transmission of beam reporting messages, interference with ACK / NACK and / or IUC signaling can be avoided within a same slot.

[0063] In some aspects, the PRBs to be used in the resources 404 of the codebook mapping 400 are selected based on a resource of the corresponding DCR message.For example, the PRBs may be selected based on a slot or sub-channel index of the PSCCH and / or PSSCH resource of the DCR message.

[0064] In some examples, the beam reporting messages of FIG. 2 or FIGS. 3A-3B include an ACK sequence with a half-bit indication. The contents (e.g., RSRP measurement) of the beam reporting message are indicated implicitly using different frequency and / or code resources according to the codebook mapping 400. By indicating the RSRP value implicitly through the use of different frequency and / or code resources, the beam reporting message can be transmitted with minimum signaling overhead. Minimizing signaling overhead may be beneficial certain scenarios, such as FIG. 2 or FIG. 3A, where the beam reporting message may be communicated using PSFCH. For example, the PSFCH may be primarily reserved for signaling such as ACK / NACK, and not be suitable for carrying large amounts of data.

[0065] In some aspects, the codebook mapping 400 additionally or alternatively indicates a source ID and / or a destination ID. For example, resources 1 -4 correspond to a first source ID, resources 5-8 correspond to a second source ID, resources 9-12 correspond to a third source ID, etc. Resources 1-4 can be mapped in ascending order to increasing RSRP values, and resources 5-8 and 9-12 can be mapped similarly. A similar methodology can be applied to additionally or alternatively indicate the destination ID.

[0066] FIG. 5 illustrates an example of a first UE 101-1 and a second UE 101-2 performing a sidelink beam pairing procedure 500 in accordance with some aspects of the present disclosure. In some aspects, the beam pairing procedure 500 represents a variation of the beam pairing procedure 100, where the UE 101 -2 performs the beam reporting based on DMRS using dedicated beam reporting slots from a resource pool.

[0067] At act 510, the UE 101 -1 and the UE 101 -2 receive a resource pool (pre)configuration. The resource pool (pre)configuration may be a pre-configuration (e.g., specified by standards and stored on the UEs 101 -1 , 101 -2) or a dynamic configuration received from the network (e.g., via a base station of the network). In some aspects, the resource pool (pre)configuration configures the UEs 101 -1 , 101-2 with one or more resources pools. The resource pool (pre)configuration may further configure dedicated slots within the one or more resource pools to be used for transmission of beam reporting messages.

[0068] At act 520, the UE 101-1 transmits one or more PSCCH transmissions using one or more Tx beams respectively (e.g., Tx beams 103). Each PSCCH transmission may indicate resources to be used for a subsequent PSSCH transmission (e.g., DCRmessage). The indication may be made, for example, using SCI. In addition to the PSCCH, the UE 101 -1 also transmits PSCCH DMRS using the one or more Tx beams respectively.

[0069] At act 530, the UE 101-1 transmits one or more PSSCH transmissions using the one or more Tx beams respectively. Each PSSCH transmission may include a DCR message indicating an intention of the UE 101 -1 to establish a unicast connection with the UE 101 -2. In addition, each PSSCH transmission may include PSSCH DMRS.

[0070] At act 540, the UE 101-2 transmits one or more beam reporting messages to the UE 101 -1 using the dedicated slots for beam reporting within the one or more resource pools. In some examples, the UE 101 -1 transmits a beam reporting message in response to a beam reporting condition being satisfied. The beam reporting condition may include an RSRP measurement of a reference signal (e.g., DMRS) exceeding a (pre)configured threshold value, or the RSRP measurement of the reference signal exceeding the RSRP measurements of all previously received reference signals associated with a same DCR message, as previously described.

[0071] In some aspects, a beam reporting message includes one or more of: a source ID, a destination ID, and an RSRP value. The source ID and the destination ID may correspond to the UEs 101 -2, 101-1 respectively. The RSRP value may be the measured RSRP of the reference signal associated with the beam reporting message. For example, if the beam reporting message is transmitted in response to a first DCR message that was transmitted by the UE 101 -1 using a first Tx beam, then the RSRP value is the RSRP measured by the UE 101-2 of the DMRS that was transmitted by the UE 101 -1 using the first Tx beam.

[0072] In some aspects, the UE 101 -2 transmits the beam reporting message in the form of SCI. For example, the beam reporting message may be carried by stage 2 SCI. The UE 101-2 may transmit stage 1 SCI indicating resources to be used for transmission of the stage 2 SCI. Subsequently, the UE 101 -2 may transmit the stage 2 SCI using the indicated resources. The stage 2 SCI may carry the contents of the beam reporting message, for example, the source ID, the destination ID, the RSRP value, etc. In some examples, the stage 1 SCI is transmitted on a PSCCH, and the stage 2 SCI is transmitted on a PSSCH.

[0073] In some aspects, the UE 101 -2 transmits the beam reporting message in the form of a medium access control (MAC) control element (CE). In some examples, the UE 101 -2 transmits SCI (e.g., stage 1 SCI) indicating resources to be used for transmission of the MAC CE. Subsequently, the UE 101 -2 may transmit the MAC CEusing the indicated resources. The MAC CE may carry the contents of the beam reporting message such as the source ID, destination ID, RSRP value, etc. In some examples, the SCI is transmitted on a PSCCH, and the MAC CE is transmitted on a PSSCH.

[0074] At act 550, the UE 101 -2 determines its optimal Tx and Rx beams for communication with the UE 101 -1 . For example, the UE 101 -2 may sweep its own Rx beam during reception of the DMRS, and identify the optimal beam as the one resulting in the highest RSRP. Further, the UE 101 -2 may determine its optimal Tx beam based on the optimal Rx beam. For example, the UE 101 -2 may determine that the optimal Tx beam is the same as the optimal Rx beam (e.g., by beam correspondence) or derived from the optimal Rx beam (e.g., a wider beam covering the optimal Rx beam).

[0075] At act 560, the UE 101-1 determines its optimal Tx and Rx beams for communication with the UE 101-2 based on the one or more beam reporting messages. For example, the UE 101 -1 may determine its optimal Tx beam based on the beam reporting message with the highest RSRP value or based on the latest received beam reporting message, depending on which beam reporting condition is used, as previously described. Further, the UE 101 -1 may determine the optimal Rx beam based on the optimal Tx beam. For example, the UE 101 -1 may determine that the optimal Rx beam is the same as the optimal Tx beam (e.g., by beam correspondence) or derived from the optimal Tx beam (e.g., a wider beam covering the optimal Tx beam).

[0076] At act 570, the UE 101 -1 and the UE 101 -2 establish a unicast link using the optimal Tx / Rx beams for the UEs 101 -1 , 101 -2, for example, as described with reference to act 150 of FIG. 1 .

[0077] FIGS. 6A-6B illustrate example beam reporting configurations 600A, 600B in accordance with some aspects of the present disclosure. In some aspects, the UE 101 - 1 transmits one or more DOR messages using one or more Tx beams. After transmitting each of the one or more DCR messages, the UE 101 -1 may monitor dedicated slots within a resource pool for a beam reporting message. The resource pool may be configured using a resource pool (pre)configuration, for example, as described with reference to FIG. 5.

[0078] In the examples of FIG. 6A-6B, similar to the examples of FIGS. 3A-3B, the UE 101 -1 is configured with Tx beams 103A, 103B, 103C and Rx beams 303A, 303B, 303C. The UE 101 -1 transmits a DCR message 602A using the Tx beam 103A at a first point in time, transmits a DCR message 602B at a second point in time, and transmits aDCR message 602C at a third point in time. The DCR messages 602A, 602B, 6020 may be, for example, the DCR messages described throughout the present disclosure.

[0079] In some aspects, the DCR messages 602A, 602B, 602C are transmitted using dedicated slots within the resource pool. For example, the resource pool (pre)configuration may configure dedicated slots for DCR, and the DCR messages 602A, 602B, 602C may be transmitted using the dedicated slots.

[0080] After transmitting a DCR message (e.g., 602A, 602B, 602C), the UE 101 -1 monitors the dedicated slots for beam reporting within the resource pool. In some aspects, the dedicated slots for beam reporting are mapped to the dedicated slots for DCR according to an association rule. The association rule, for example, may indicate one or more slot offsets between the dedicated slots for DCR and the dedicated slots for beam reporting. The association rule may be (pre)configured (e.g., by the resource pool (pre)configuration), or dynamically indicated using SCI. For example, the DCR message may be transmitted by the UE 101 -1 in the form of stage 2 SCI, and the stage 2 SCI may indicate the association rule.

[0081] In some aspects, the beam reporting configurations 600A, 600B correspond to the beam pairing procedure 500 of FIG. 5 when using different beam reporting conditions. For example, in FIG. 6A, the beam reporting condition includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding a (pre)configured threshold value. Further, in FIG. 6B, the beam reporting condition includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding the RSRP measurements of all previously received reference signals associated with the same DCR message.

[0082] As shown in FIG. 6A, the UE 101-1 transmits the DCR message 602A using the Tx beam 103A. The PSCCH and / or PSSCH associated with the DCR message may include PSCCH and / or PSSCH DMRS, which may be measured by the UE 101-2 in order to evaluate the beam reporting condition, as previously described. Subsequently, the UE 101 -1 monitors for a beam reporting message using the Rx beam 303A.Monitoring for the beam reporting message may include monitoring the dedicated slots for beam reporting within the resource pool, as previously described. In the illustrated example, the beam reporting condition is not satisfied, and no beam reporting message is transmitted by the UE 101 -2 in response to the DCR message 602A. For example, the measured RSRP of the PSCCH and / or PSSCH DMRS associated with the DCR message does not exceed the (pre)configured threshold value.

[0083] Subsequently, the UE 101-1 transmits the DCR message 602B, and monitors for a beam reporting message using the Rx beam 303B. In the illustrated example, theRSRP measurement of DMRS associated with the DCR message 602B is greater than the (pre)configured threshold value, such that the beam reporting condition is satisfied. In response to the beam reporting condition being satisfied, the UE 101 -2 transmits a beam reporting message 604B to the UE 101 -1 . The UE 101 -2 may identify a slot for transmission of the beam reporting message 604B from the plurality of dedicated slots for beam reporting within the resource pool, for example, based on a slot of the DCR message 602B and the association rule. The beam reporting message may be in the form of a MAC CE or stage 2 SCI, as described with reference to FIG. 5.

[0084] Subsequently, the UE 101 -1 transmits the DCR message 602C, and monitors for a beam reporting message using the Rx beam 303C. In the illustrated example, the beam reporting condition is not satisfied, and no beam reporting message is transmitted by the UE 101 -2 in response to the DCR message 602C.

[0085] Based on the beam reporting message(s), the UE 101-1 determines that the Tx beam 103B is the optimal beam for serving the UE 101 -2. For example, the Tx beam 103B is determined as the optimal beam in response to the corresponding beam reporting message 604B being the beam reporting message with the highest indicated RSRP value associated with a same DCR message. For example, the DCR messages 602A, 602B, 602C may be considered a “same” DCR message transmitted on different beams.

[0086] As shown in FIG. 6B, similar to FIG. 6A, the UE 101 -1 transmits the DCR message 602A, which is received by the UE 101 -2. As previously mentioned, the beam reporting condition of FIG. 6B includes an RSRP measurement of a reference signal (e.g., DMRS) exceeding the RSRP measurements of all previously received reference signals associated with the same DCR message, which differs from the beam reporting condition of FIG. 6A. As a result, the UE 101 -2 transmits a beam reporting message 604A in response to the DCR message 302A, which is received by the UE 101 -1 using the Rx beam 303A. In the example of FIG. 6B, since the DCR message 602A is the first DCR message received, the associated DMRS RSRP measurement is the new highest RSRP measurement, and the beam reporting condition is satisfied. In response to the beam reporting condition being satisfied, the UE 101-2 transmits the beam reporting message 604A.

[0087] Further, in the example of FIG. 6B, the measured RSRP of DMRS associated with the DCR message 602B is higher than the measured RSRP of DMRS associatedwith the DCR message 602A. Therefore, the beam reporting condition is satisfied. In response, the UE 101 -2 transmits the beam reporting message 604B.

[0088] Based on the beam reporting messages, the UE 101-1 determines that the Tx beam 103B is the optimal beam for serving the UE 101 -2. For example, the Tx beam 103B is determined as the optimal beam in response to the corresponding beam reporting message 604B being the latest received beam reporting message.

[0089] FIG. 7 illustrates an example of a first UE 101-1 and a second UE 101-2 performing a sidelink beam pairing procedure 700 in accordance with some aspects of the present disclosure. In some aspects, the beam pairing procedure 700 represents a variation of the beam pairing procedure 100, where the UE 101 -2 performs the beam reporting based on CSI-RS using dedicated beam reporting slots from a resource pool.

[0090] At act 710, the UE 101 -1 and the UE 101 -2 receive a resource pool (pre)configuration. The resource pool (pre)configuration may be the resource pool (pre)configuration as previously described, and configure one or more resource pools with dedicated slots for transmission of beam reporting messages.

[0091] At act 720, the UE 101-1 transmits one or more SCI using one or more Tx beams respectively (e.g., Tx beams 103). Each SCI transmission may indicate resources to be used for transmission of a DCR message. In some examples, the SCI is transmitted on a PSCCH, and the DCR message is transmitted on a PSSCH. In some aspects, the SCI indicates a source ID. Additionally or alternatively, the SCI may indicate a destination ID. For example, the source ID corresponds to the UE 101 -1 , and the destination ID corresponds to the UE 101 -2

[0092] At act 730, the UE 101 -1 transmits one or more DCR messages using the one or more Tx beams respectively. The UE 101 -1 may transmit the one or more DCR messages, for example, using resources indicated in the one or more SCI respectively.

[0093] At act 740, the UE 101-1 transmits one or more sidelink CSI-RS using the one or more Tx beams respectively. In some aspects, each CSI-RS has an associated SCI which includes a source ID and / or a destination ID. For example, the UE 101 -1 may transmit the SCI before the associated CSI-RS. Additionally, the SCI may indicate resources to be used for transmission of the associated CSI-RS. The CSI-RS may be transmitted in a periodic or semi-persistent manner.

[0094] In some aspects, the SCI further indicates a sidelink CSI-RS resource to be used for evaluating the beam reporting condition. For example, at act 720, the UE 101-1 transmits a first SCI indicating resources for transmission of a first DCR message. The first SCI may indicate a first CSI-RS to be used for evaluating the Tx beamcorresponding to the first DCR message. For example, the first SCI may include a sidelink CSI-RS resource ID of the first CSI-RS, or a sidelink transmission configuration indicator (TCI) state. The SCI may additionally or alternatively indicate time resources, frequency resources, and / or a periodicity to be used for the CSI-RS.

[0095] At act 750, the UE 101-2 transmits one or more beam reporting messages to the UE 101 -1 using the dedicated slots for beam reporting within the one or more resource pools. In some examples, the UE 101 -1 transmits a beam reporting message in response to a beam reporting condition being satisfied. The beam reporting message may be in the form of a MAC CE or stage 2 SCI, as previously described. The beam reporting message may include one or more of: a source ID, a destination ID, RSRP measurement value, or a sidelink CSI-RS resource ID. In some examples, the beam reporting message is transmitted in response to a DCR message, and the RSRP measurement value and / or the CSI-RS resource ID correspond to the CSI-RS that is associated (e.g., quasi co-located (QCLed)) with the DCR message.

[0096] The beam reporting condition may include an RSRP measurement of a reference signal (e.g., sidelink CSI-RS) exceeding a (pre)configured threshold value, or the RSRP measurement of the reference signal exceeding the RSRP measurements of all previously received reference signals, as previously described. In some aspects, the UE 101 -2 determines a slot (e.g., for transmission) of a beam reporting message based on a slot of the corresponding DCR message. In some alternative aspects, the UE 101 - 2 determines the slot of the beam reporting message based on a slot of an associated CSI-RS.

[0097] At act 760, the UE 101 -2 determines its optimal Tx and Rx beams for communication with the UE 101 -1 . For example, the UE 101 -2 may sweep its own Rx beam during reception of the CSI-RS, and identify the optimal beam as the one resulting in the highest RSRP. Further, the UE 101 -2 may determine its optimal Tx beam based on the optimal Tx beam. For example, the UE 101 -2 may determine that the optimal Tx beam is the same as the optimal Rx beam (e.g., by beam correspondence) or derived from the optimal Rx beam (e.g., a wider beam covering the optimal Rx beam).

[0098] At act 770, the UE 101-1 determines its optimal Tx and Rx beams for communication with the UE 101-2 based on the one or more beam reporting messages. For example, the UE 101 -1 may determine its optimal Tx beam based on the beam reporting message with the highest RSRP value or based on the latest received beam reporting message, depending on which beam reporting condition is used, as previouslydescribed. Further, the UE 101 -1 may determine the optimal Rx beam based on the optimal Tx beam. For example, the UE 101 -1 may determine that the optimal Rx beam is the same as the optimal Tx beam (e.g., by beam correspondence) or derived from the optimal Tx beam (e.g., a wider beam covering the optimal Tx beam).

[0099] At act 780, the UE 101 -1 and the UE 101 -2 establish a unicast link using the optimal Tx / Rx beams for the UEs 101 -1 , 101 -2, for example, as described with reference to act 150 of FIG. 1 .

[0100] FIGS. 8A-8B illustrate example beam reporting configurations 800A, 800B in accordance with some aspects of the present disclosure. In some aspects, the UE 101 - 1 transmits one or more sidelink CSI-RS and one or more DCR messages using one or more Tx beams. After transmitting each of the one or more DCR messages, the UE 101-1 may monitor dedicated slots within a resource pool for a beam reporting message. The resource pool may be configured using a resource pool (pre)configuration, for example, as described with reference to FIG. 5 or FIG. 7.

[0101] In the examples of FIGS. 8A-8B, similar to the examples of FIGS. 3A-3B or FIGS. 6A-6B, the UE 101 -1 is configured with Tx beams 103A, 103B, 103C and Rx beams 303A, 303B, 303C. The UE 101 -1 transmits a DCR message 802A at a first point in time, transmits a DCR message 802B at a second point in time, and transmits a DCR message 802C at a third point in time. The DCR messages 802A, 802B, 802C may be, for example, the DCR messages described throughout the present disclosure. Similar to FIGS. 6A-6B, the DCR messages 802A, 802B, 802C may be transmitted using dedicated slots within the resource pool. For example, the resource pool (pre)configuration may configure dedicated slots for DCR, and the DCR messages 802A, 802B, 802C may be transmitted using the dedicated slots.

[0102] FIGS. 8A-8B additionally illustrate sidelink CSI-RS 806A, 806B, 806C, 806D, 806E, 806F. As shown, the UE 101-1 transmits the CSI-RS 806A, 806B, 806C during a first CSI-RS period 808A using the Tx beams 103A, 103B, 103C respectively. During the second CSI-RS period 808B, the UE 101 -1 transmits the CSI-RS 806D, 806E, 806F using the Tx beams 103A, 103B, 103C respectively. The second CSI-RS period 808B may be temporally offset from the first CSI-RS period 808A, for example, according to a sidelink CSI-RS periodicity.

[0103] The UE 101-1 monitors for a beam reporting message during dedicated slots for beam reporting within the resource pool. In some aspects, as shown in FIG. 8A, the monitored slots are configured based on a CSI-RS resource associated with a DCRmessage. In some additional or alternative aspects, as shown in FIG. SB, the monitored slots are configured based on a resource of the DCR message.

[0104] As shown in FIG. 8A, the UE 101-1 may monitor for beam reporting based on a time offset from a transmission of a CSI-RS associated with a DCR message. In some examples, the CSI-RS is QCLed (e.g., QCL type D) with the associated DCR message. For example, the DCR message 802A is QCLed with the CSI-RS 806A, 806D since both the DCR message 802A and the CSI-RS 806A, 806D are transmitted using the Tx beam 103A. Although the present example illustrates a single Tx beam 103A for both DCR and CSI-RS transmission, in alternative examples, the DCR message 802A and the CSI-RS 806A, 806D are transmitted using different beams (e.g., wider or narrower beams) that are QCLed.

[0105] The UE 101-1 may transmit CSI-RS periodically, as shown by the first CSI- RS period 808A and the second CSI-RS period 808B. In some examples, the UE 101 -1 begins transmitting the CSI-RS after determining to initiate a unicast link (e.g., with the UE 101 -2). However, in alternative examples, the UE 101 -1 is already transmitting CSI- RS upon determining to establish the unicast link.

[0106] After the first CSI-RS period 808A, the UE 101 -1 transmits DCR messages 802A, 802B, 802C using the Tx beams 103A, 103B, 103C respectively. The DCR messages 802A, 802B, and / or 802C may be received by the UE 101-2. In response to receiving a DCR message, the UE 101 -2 may measure RSRP of the CSI-RS during the next CSI-RS period 808B. In the illustrated example, in response to the CSI-RS 806E (transmitted using the beam 103B) satisfying a beam reporting condition, the UE 101 -2 transmits a beam reporting message 804E. A slot of the beam reporting message 804E, for example, may be determined based on a slot of the CSI-RS 806E and an association rule. The association rule may be (pre)configuration (e.g., by the resource pool (pre)configuration) or dynamically indicating using SCI. The UE 101 -1 may monitor for and receive the beam reporting message 804E using the Rx beam 303B. The monitored slot may be determined based on a slot of the CSI-RS 806E and the association rule.

[0107] Alternatively, as shown in FIG. 8B, the UE 101 -1 may monitor for beam reporting based on a time offset from transmission of a DCR message. As previously described, the UE 101 -1 may transmit CSI-RS periodically, as shown by the first CSI- RS period 808A and the second CSI-RS period 808B. In the example of FIG. 8A, the UE 101 -2 does not begin to measure CSI-RS until a DCR message associated with (e.g., QCLed with) the CSI-RS is received. However, in the example of FIG. 8B, the UE101-2 may be configured to measure CSI-RS before reception of an associated DCR message. For example, the UE 101 -2 measures RSRP of CSI-RS 806A, 806B, 806C during the first CSI-RS period 808A.

[0108] Subsequently, the UE 101-2 receives DCR messages 802A, 802B, 802C from the UE 101 -1 . Since the UE 101 -2 has already measured CSI-RS during the first CSI-RS period 808A, the UE 101 -2 does not need to wait until the next CSI-RS period 808A to perform measurements and evaluate the beam reporting condition. Upon reception of the DCR messages 802A, 802B, 802C, the UE 101 -2 may evaluate the beam reporting condition based on the previous measurements of the CSI-RS 806A, 806B, 806C. In the illustrated example, the CSI-RS 806B satisfies the beam reporting condition. In response, the UE 101 -2 transmits the beam reporting message 804B to the UE 101 -1 . A slot of the beam reporting message 804B, for example, may be determined based on a slot of the DCR message 802B and an association rule, as previously described. The UE 101-1 may monitor for and receive the beam reporting message 804B using the Rx beam 303B. The monitored slot may be determined based on a slot of the DCR message 802B and the association rule.

[0109] In the examples of FIGS. 8A-8B, the beam reporting condition may include an RSRP measurement of the CSI-RS exceeding a (pre)configured threshold value. However, in alternative examples, the beam reporting condition may include an RSRP measurement of the CSI-RS exceeding all previous RSRP measurements of CSI-RS associated with a same beam reporting message. Furthermore, although CSI-RS is used in the examples of FIGS. 8A-8B, in alternative examples, other types of reference signals (e.g., S-SSB) may be used.

[0110] FIGS. 9-10 are flow diagrams illustrating process flows 900, 1000 for UEs performing a beam pairing procedure in accordance with some aspects of the present disclosure.

[0111] The process flow 900 shown in FIG. 9 may be performed by a UE, such as the UE 101 -1 as described throughout the present disclosure.

[0112] At act 910, the UE transmits one or more DCR messages to a second UE (e.g., the UE 101 -2) using one or more respective Tx beams (e.g., the Tx beams 103). The one or more DCR messages may be the one or more DCR messages described throughout the present disclosure.

[0113] At act 920, the UE transmits one or more reference signals to the second UE using the one more respective Tx beams. The reference signals may include, forexample, PSCCH DMRS, PSSCH DMRS, sidelink CSI-RS, or S-SSB, as previously described.

[0114] At act 930, the UE receives one or more beam reporting messages from the second UE. The beam reporting message, for example, may be received using a PSFCH or a PSSCH (e.g., using dedicated beam reporting slots in a resource pool), as described throughout the present disclosure. In some examples, the one or more beam reporting messages indicate the values of RSRP measurements performed by the second UE on the one or more reference signals. The RSRP measurements may be indicated, for example, using a codebook mapping as described with reference to FIG. 4.

[0115] At act 940, the UE identifies an optimal Tx beam for communication with the second UE based on the one or more beam reporting messages. In some examples, the optimal Tx beam is identified from the one or more Tx beams used to transmit the DCR and reference signals. Each beam reporting message may be associated with a Tx beam. In some examples, the Tx beam associated with the beam reporting message with the highest indicated RSRP measurement value is identified as the optimal Tx beam. In some alternative examples, the Tx beam associated with the latest received beam reporting message associated with a same DCR message is identified as the optimal Tx beam, as previously described. The UE may further determine its optimal Rx beam for communication with the second UE based on the optimal Tx beam. For example, the optimal Rx beam may be the same as the optimal Tx beam, or derived from the optimal Tx beam.

[0116] At act 950, the UE communicates with the second UE using the optimal Tx beam and / or the optimal Rx beam. For example, the UE may transmit or receive data (e.g., on a PSSCH) to or from the second UE by exchanging signaling with the second UE using the optimal Tx and / or Rx beams.

[0117] The process flow 1000 as shown in FIG. 10 may be performed by a UE, such as the UE 101-2 as described throughout the present disclosure.

[0118] At act 1010, the UE receives one or more DCR messages from a second UE (e.g., the UE 101 -1). The one or more DCR messages may be the one or more DCR messages described throughout the present disclosure. In some examples, the one or more DCR messages are associated with one or more Tx beams of the second UE respectively.

[0119] At act 1020, the UE receives one or more reference signals from the second UE. The one or more reference signals may be associated with the one or more Txbeams of the second UE respectively. The reference signals may include, for example, PSCCH DMRS, PSSCH DMRS, sidelink CSI-RS, or S-SSB, as previously described. In some examples, the UE measures the one or more reference signals (e.g., by measuring RSRP) in order to evaluate a beam reporting condition.

[0120] At act 1030, the UE transmits a beam reporting message to the second UE. In some aspects, the beam reporting message is transmitted based on a reference signal of the one or more reference signals. For example, the beam reporting message is transmitted in response to a DCR message, and the beam reporting message indicates an RSRP value of a reference signal associated with (e.g., QCLed with) the DCR message. The beam reporting message may be transmitted in response to a beam reporting condition being satisfied, and may be transmitted using a PSFCH or a PSSCH (e.g., using dedicated beam reporting slots in a resource pool), as described throughout the present disclosure.

[0121] At act 1040, the UE determines an optimal Rx beam for communication with the second UE. For example, the UE may perform Rx beam sweeping by measuring (e.g., RSRP) the one or more reference signals using various Rx beams. The optimal Rx beam may be determined based on the Rx beam sweeping, as the Rx beam that results in the highest RSRP value. The UE may further determine an its optimal Tx beam for communication with the second UE based on the optimal Rx beam. For example, the optimal Tx beam may be the same as the optimal Rx beam, or derived from the optimal Rx beam.

[0122] At act 1050, the UE communicates with the second UE using the optimal Rx beam and / or the optimal Tx beam. For example, the UE may receive or transmit data (e.g., on a PSSCH) from or to the second UE using the optimal Rx and / or Tx beams.

[0123] FIG. 1 1 is a block diagram illustrating an example wireless network 1 100 in accordance with some aspects of the present disclosure. In the illustrated example, the network includes, a UE 101 -1 , a UE 101 -2, and a radio access network (RAN) 1 1 10. In some examples the UEs 101 -1 , 101 -2 are the UEs 101 -1 , 101 -2 are configured to perform a sidelink beam pairing procedure, as described throughout the present disclosure. Although a UE 101 -1 and a UE 101 -2 are illustrated, alternative examples may include more or fewer UEs.

[0124] The UEs 101 -1 , 101 -2 can be configured to connect, for example, communicatively coupled, with the RAN 1 1 10. The RAN 11 10 may include one or more base stations 1 1 11. The UEs 101 -1 , 101 -2 may use connections or channels 1104, 1 102, 1 106 for uplink (UL), downlink (DL), and sidelink respectively. The systems anddevices of the network 1100 may operate in accordance with one or more communication standards, such as the 2G, 3G, 4G, and / or 5G communication standards of 3GPP.

[0125] The UE 101-1 and / or the UE 101 -2 may comprise any mobile or non-mobile computing device, such as consumer electronics devices, cellular phones, smartphones, feature phones, tablet computers, wearable computer devices, personal digital assistants (PDAs), pagers, wireless handsets, desktop computers, laptop computers, in-vehicle infotainment (I VI), in-car entertainment (ICE) devices, an Instrument Cluster (IC), head-up display (HUD) devices, onboard diagnostic (OBD) devices, dashtop mobile equipment (DME), mobile data terminals (MDTs), Electronic Engine Management System (EEMS), electronic / engine control units (ECUs), electronic / engine control modules (ECMs), embedded systems, microcontrollers, control modules, engine management systems (EMS), networked or “smart” appliances, Machine Type Communication (MTC) devices, Machine to Machine (M2M), Internet of Things (loT) devices, and / or the like.

[0126] In some aspects, the RAN 1110 can be a next generation (NG) RAN or a 5G RAN, an evolved-UMTS Terrestrial RAN (E-UTRAN), or a legacy RAN, such as a UTRAN or GERAN. As used herein, the term “NG RAN” or the like can refer to a RAN 1110 that operates in an NR or 5G system, and the term “E-UTRAN” or the like can refer to a RAN 1110 that operates in an LTE or 4G system.

[0127] FIG. 12 is a diagram illustrating example components of a device 1200 that can be employed in accordance with some aspects of the present disclosure. In some aspects, the device 1200 can include application circuitry 1202, baseband circuitry 1204, Radio Frequency (RF) circuitry 1206, front-end module (FEM) circuitry 1208, one or more antennas 1210, and power management circuitry (PMC) 1212 coupled together at least as shown. The components of the illustrated device 1200 can be included in a UE or a RAN node such as the UE 101 -1 , UE 101 -2, or base station 1111 as described throughout the present disclosure. The UE 101 -1 and / or the UE 101 -2 may be configured to perform a sidelink beam pairing procedure, as described throughout the present disclosure. In some implementations, the device 1200 can include fewer elements (e.g., a RAN node may not utilize application circuitry 1202 and instead include a processor / controller to process IP data received from a CN, which may be a 5GC or an Evolved Packet Core (EPC)). In some implementations, the device 1200 can include additional elements such as, for example, memory / storage, display, camera, sensor (including one or more temperature sensors, such as a single temperaturesensor, a plurality of temperature sensors at different locations in device 1200, etc.), or input / output (I / O) interface. In other implementations, the components described below can be included in more than one device (e.g., said circuitries can be separately included in more than one device for Cloud-RAN (C-RAN) implementations).

[0128] The application circuitry 1202 can include one or more application processors. For example, the application circuitry 1202 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) can include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors can be coupled with or can include memory / storage and can be configured to execute instructions stored in the memory / storage to enable various applications or operating systems to run on the device 1200. In some implementations, processors of application circuitry 1202 can process IP data packets received from an EPC.

[0129] The baseband circuitry 1204 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1204 can include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 1206 and to generate baseband signals for a transmit signal path of the RF circuitry 1206. Baseband circuitry 1204 can interface with the application circuitry 1202 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1206. For example, in some implementations, the baseband circuitry 1204 can include a 3G baseband processor 1204A, a 4G baseband processor 1204B, a 5G baseband processor 1204C, or other baseband processor(s) 1204D for other existing generations, generations in development or to be developed in the future (e.g., 2G, 6G, etc.).

[0130] The baseband circuitry 1204 (e.g., one or more of baseband processors 1204A-D) can handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1206. In other implementations, some or all of the functionality of baseband processors 1204A-D can be included in modules stored in the memory 1204G and executed via a Central Processing Unit (CPU) 1204E. The radio control functions can include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some implementations, the baseband circuitry 1204 can include one or more audio digital signal processor(s) (DSP) 1204F.

[0131] RF circuitry 1206 can enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In variousimplementations, the RF circuitry 1206 can include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1206 can include a receive signal path which can include circuitry to down-convert RF signals received from the FEM circuitry 1208 and provide baseband signals to the baseband circuitry 1204. RF circuitry 1206 can also include a transmit signal path which can include circuitry to up-convert baseband signals provided by the baseband circuitry 1204 and provide RF output signals to the FEM circuitry 1208 for transmission.

[0132] In some implementations, the receive signal path of the RF circuitry 1206 can include mixer circuitry 1206A, amplifier circuitry 1206B and filter circuitry 1206C. In some implementations, the transmit signal path of the RF circuitry 1206 can include filter circuitry 1206C and mixer circuitry 1206A. RF circuitry 1206 can also include synthesizer circuitry 1206D for synthesizing a frequency for use by the mixer circuitry 1206A of the receive signal path and the transmit signal path.

[0133] Examples herein can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including executable instructions that, when performed by a machine (e.g., a processor (e.g., processor , etc.) with memory, an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like) cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to implementations and examples described.

[0134] Example 1 is a baseband processor for a user equipment (UE) comprising one or more processors. The one or more processors are configured to execute instructions stored in a memory to cause the UE to: receive one or more direct connection request (DCR) messages from a second UE, wherein the one or more DCR messages are associated with one or more transmit (Tx) beams of the second UE respectively, receive one or more reference signals from the second UE, the one or more reference signals associated with the one or more Tx beams of the second UE respectively, transmit a beam reporting message to the second UE based on a first reference signal of the one or more reference signals, determine an optimal receive (Rx) beam of the UE for communication with the second UE based on the one or more reference signals, and communicate with the second UE using the optimal Rx beam.

[0135] Example 2 comprises the subject matter of any variation of example 1 , wherein the one or more processors further cause the UE to transmit the beam reporting message to the second UE on a physical sidelink feedback channel (PSFCH).

[0136] Example 3 comprises the subject matter of any variation of example 2,wherein the one or more processors further cause the UE to: in response to a first DCR message of the one or more DCR messages, transmit an acknowledgement (ACK) I negative acknowledgement (NACK) message to the second UE on the PSFCH, wherein the first reference signal and the first DCR message are associated with a same Tx beam of the one or more Tx beams of the second UE.

[0137] Example 4 comprises the subject matter of any variation of example 3, wherein the one or more processors further cause the UE to: transmit the ACK / NACK message in a same slot as the beam reporting message using different frequency or code resources than the beam reporting message.

[0138] Example 5 comprises the subject matter of any variation of example 3, wherein the one or more processors further cause the UE to: transmit the beam reporting message after the ACK / NACK message based on a (pre)configured time offset.

[0139] Example 6 comprises the subject matter of any variation of example 2, wherein the one or more processors further cause the UE to transmit the beam reporting message in response to one or more conditions being satisfied, the one or more conditions including at least one of: successfully decoding a first DCR message of the one or more DCR messages, wherein the first reference signal and the first DCR message are associated with a same Tx beam of the one or more Tx beams of the UE, a determination to establish a unicast connection with the second UE, or a measurement of the first reference signal exceeding a measurement threshold value.

[0140] Example 7 comprises the subject matter of any variation of example 6, wherein the measurement threshold value comprises a reference signal received power (RSRP) threshold value, wherein the RSRP threshold value is one of: a (pre)configured value, or determined based on a highest RSRP measurement of reference signals received before the first reference signal.

[0141] Example 8 comprises the subject matter of any variation of example 1 , wherein the one or more processors further cause the UE to: determine, based on the optimal Rx beam of the UE, an optimal Tx beam of the UE for communication with the second UE, wherein the optimal Tx beam is one of: the same as the optimal Rx beam, or derived from the optimal Rx beam.

[0142] Example 9 comprises the subject matter of any variation of example 1 , wherein the beam reporting message includes an acknowledgement (ACK) sequence with a half-bit indication.

[0143] Example 10 comprises the subject matter of any variation of example 1 ,wherein the beam reporting message indicates an RSRP measurement of the first reference signal based on a codebook mapping.

[0144] Example 11 comprises the subject matter of any variation of example 10, wherein the beam reporting message further indicates, based on the codebook mapping, at least one of: a source ID and a destination ID.

[0145] Example 12 comprises the subject matter of any variation of example 10, wherein the codebook mapping includes a mapping between RSRP measurement values and one or more of: frequency resources or code resources used for transmission of the beam reporting message.

[0146] Example 13 comprises the subject matter of any variation of example 12, wherein the frequency resources comprise physical resource blocks (PRBs), and wherein the code resources comprise cyclic shift pairs.

[0147] Example 14 comprises the subject matter of any variation of example 1 , wherein the beam reporting message is transmitted in response to a first DCR message of the one or more DCR messages, and wherein a slot of the beam reporting message is based on a slot of the first DCR message.

[0148] Example 15 comprises the subject matter of any variation of example 1 , wherein the one or more processors further cause the UE to: determine the optimal Rx beam of the UE in response to the optimal Rx beam being associated with a highest RSRP measurement.

[0149]

[0150] Example 16 comprises the subject matter of any variation of example 1 , wherein the one or more reference signals comprise one of: physical sidelink control channel (PSCCH) demodulation reference signals (DM-RSs), physical sidelink shared channel (PSSCH) DM-RSs, sidelink channel state information reference signals (CSI- RSs), or sidelink synchronization signal block (S-SSB) signals.

[0151] Example 17 comprises the subject matter of any variation of example 1 , wherein the beam reporting message is transmitted in response to a first DCR message of the one or more DCR messages, and wherein the one or more processors further cause the UE to: identify a slot of the beam reporting message from a plurality of dedicated slots for beam reporting based on a slot of the first DCR message and an association rule, and transmit the beam reporting message in the identified slot.

[0152] Example 18 comprises the subject matter of any variation of example 17, wherein the one or more processors further cause the UE to: receive a resource pool(pre)configuration that configures the plurality of dedicated slots for beam reporting.

[0153] Example 19 comprises the subject matter of any variation of example 18, wherein the resource pool (pre)configuration further configures the association rule.

[0154] Example 20 comprises the subject matter of any variation of example 17, wherein the one or more processors further cause the UE to: receive sidelink control information (SCI) to schedule the first DCR message, wherein the SCI indicates the association rule.

[0155] Example 21 comprises the subject matter of any variation of example 1 , wherein the beam reporting message comprises a medium access control (MAC) control element (CE), the MAC CE including one or more of: a source identity (ID), a destination ID, a reference signal received power (RSRP) measurement of the first reference signal, and a sidelink channel state information reference signal (CSI-RS) resource ID.

[0156] Example 22 comprises the subject matter of any variation of example 1 , the beam reporting message comprises sidelink control information (SCI), the SCI including one or more of: a source identity (ID), a destination ID, a reference signal received power (RSRP) measurement of the first reference signal, and a sidelink channel state information reference signal (CSI-RS) resource ID.

[0157] Example 23 comprises the subject matter of any variation of example 1 , wherein the beam reporting message is transmitted in response to a first DCR message of the one or more DCR messages, and wherein the one or more processors further cause the UE to: receive sidelink control information (SCI) to schedule the first DCR message, wherein the SCI indicates a first reference signal of the one or more reference signals associated with a same Tx beam of the second UE as the first DCR message, the first reference signal comprising a first sidelink channel state information reference signal (CSI-RS), identify a slot of the beam reporting message from a plurality of dedicated slots for beam reporting based on a slot of the first CSI-RS and an association rule, and transmit the beam reporting message in the identified slot.

[0158] Example 24 is a baseband processor for a user equipment (UE) comprising one or more processors. The one or more processors are configured to execute instructions stored in a memory to cause the UE to: transmit one or more direct connection request (DCR) messages using a one or more respective transmit (Tx) beams, transmit one or more reference signals using the one or more respective Tx beams, receive one or more beam reporting messages from a second UE, wherein the one or more beam reporting messages are associated with one or more beams of theone or more Tx beams, identify an optimal Tx beam for communication with the second UE based on the one or more beam reporting messages, and communicate with the second UE using the optimal Tx beam.

[0159] Example 25 comprises the subject matter of any variation of example 24, wherein the one or more processors further cause the UE to: determine, based on the optimal Tx beam, an optimal receive (Rx) beam of the UE for communication with the second UE, wherein the optimal Rx beam is one of: the same as the optimal Tx beam, or derived from the optimal Tx beam.

[0160] Example 26 comprises the subject matter of any variation of example 24, wherein the one or more processors further cause the UE to: identify the optimal Tx beam in response to a beam reporting message associated with the optimal Tx beam being a most recently received beam reporting message of the one or more beam reporting messages.

[0161] Example 27 comprises the subject matter of any variation of example 24, wherein the one or more beam reporting messages indicate one or more reference signal received power (RSRP) measurements, and wherein the one or more processors further cause the UE to: identify the optimal Tx beam in response to an RSRP measurement associated with the optimal Tx beam being a largest RSRP measurement indicated by the one or more beam reporting messages.

[0162] Example 28 comprises the subject matter of any variation of example 24, wherein the one or more reference signals comprise one or more sidelink channel state information reference signals (CSI-RSs).

[0163] Example 29 comprises the subject matter of any variation of example 28, wherein the one or more CSI-RSs are periodic or semi-persistent.

[0164] Example 30 comprises the subject matter of any variation of example 28, wherein the one or more CSI-RSs include a source ID.

[0165] Example 31 comprises the subject matter of any variation of example 28, wherein the one or more processors further cause the UE to: transmit sidelink control information (SCI) to schedule a first DCR message of the one or more of DCR messages, wherein the SCI includes one or more of: a source identity (ID), a destination ID, a sidelink transmission configuration indicator (TCI) state, a sidelink CSI-RS resource ID of a first sidelink CSI-RS resource, time frequency resources of the first CSI-RS resource, and a periodicity of the first CSI-RS resource, wherein the first CSI- RS resource is associated with a same Tx beam as the first DCR message.

[0166] Example 32 comprises the subject matter of any variation of example 24,wherein: the one or more Tx beams includes the optimal Tx beam, or the optimal Tx beam is derived based on one of the one or more Tx beams.

[0167] Example 33 comprises the subject matter of any variation of example 24, wherein the one or more processors further cause the UE to: transmit a first DCR message of the one or more DCR messages using a first Tx beam of the one or more Tx beams, and monitor for a first beam reporting message of the one or more beam reporting messages using a first Rx beam, wherein the first beam reporting message contains beam reporting information for the first Tx beam, and wherein the first Rx beam is one of: the same as the first Tx beam, or derived from the first Tx beam.

[0168] Example 34 is a method for a user equipment (UE). The method comprises: receiving one or more direct connection request (DCR) messages from a second UE, wherein the one or more DCR messages are associated with one or more transmit (Tx) beams of the second UE respectively, receiving one or more reference signals from the second UE, the one or more reference signals associated with the one or more Tx beams of the second UE respectively, transmitting a beam reporting message to the second UE based on a first reference signal of the one or more reference signals, determining an optimal receive (Rx) beam of the UE for communication with the second UE based on the one or more reference signals, and communicating with the second UE using the optimal Rx beam.

[0169] Example 35 is a user equipment (UE) comprising radio frequency (RF) circuitry and one or more processors. The one or more processors are configured to execute instructions stored in a memory to cause the UE to: receive, from a second UE, one or more direct connection request (DCR) messages associated with one or more transmit (Tx) beams of the second UE respectively; receive, from the second UE, one or more reference signals associated with the one or more Tx beams of the second UE respectively; transmit, via the RF circuitry, a beam reporting message to the second UE based on a first reference signal of the one or more reference signals; determine an optimal receive (Rx) beam of the UE for communication with the second UE based on the one or more reference signals; and communicating with the second UE via the RF circuitry using the optimal Rx beam.

[0170] Example 36 is a method for a user equipment (UE). The method comprises: transmitting one or more direct connection request (DCR) messages using one or more respective transmit (Tx) beam; transmitting one or more reference signals using the one or more respective Tx beams; receiving, from a second UE, one or more beam reporting messages associated with one or more beams of the one or more Tx beams;identifying an optimal Tx beam for communication with the second UE based on the one or more beam reporting messages; and communicating with the second UE using the optimal Tx beam.

[0171] Example 37 is a user equipment (UE) comprising radio frequency (RF) circuitry and one or more processors. The one or more processors are configured to executed instructions stored in a memory to cause the UE to: transmit, via the RF circuitry, one or more direct connection request (DCR) messages using one or more respective transmit (Tx) beams; transmit one or more reference signals using the one or more respective Tx beams; receive, from a second UE, one or more beam reporting messages associated with one or more beams of the one or more Tx beams; identify an optimal Tx beam for communication with the second UE based on the one or more beam reporting messages; and communicate with the second UE via the RF circuitry using the optimal Tx beam.

[0172] The above description of illustrated examples, implementations, aspects, etc., of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed aspects to the precise forms disclosed. While specific examples, implementations, aspects, etc., are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such examples, implementations, aspects, etc., as those skilled in the relevant art can recognize.

[0173] In this regard, while the disclosed subject matter has been described in connection with various examples, implementations, aspects, etc., and corresponding Figures, where applicable, it is to be understood that other similar aspects can be used or modifications and additions can be made to the disclosed subject matter for performing the same, similar, alternative, or substitute function of the subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single example, implementation, or aspect described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.

[0174] In particular regard to the various functions performed by the above described components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs thefunction in the herein illustrated exemplary implementations. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

[0175] As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” Additionally, in situations wherein one or more numbered items are discussed (e.g., a “first X”, a “second X”, etc.), in general the one or more numbered items can be distinct, or they can be the same, although in some situations the context may indicate that they are distinct or that they are the same.

[0176] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

CLAIMSWhat is claimed is:1 . A baseband processor for a user equipment (UE) configured to, when executing instructions stored in a memory, perform operations comprising: receiving, from a second UE, one or more direct connection request (DCR) messages associated with one or more transmit (Tx) beams of the second UE respectively; receiving, from the second UE, one or more reference signals associated with the one or more Tx beams of the second UE respectively; providing, to a radio frequency (RF) interface for transmission to the second UE, a beam reporting message based on a first reference signal of the one or more reference signals; determining an optimal receive (Rx) beam of the UE for communication with the second UE based on the one or more reference signals; and communicating with the second UE via the RF interface using the optimal Rx beam.

2. The baseband processor of claim 1 , wherein the operations further comprise: providing the beam reporting message for transmission to the second UE on a physical sidelink feedback channel (PSFCH); and in response to a first DCR message of the one or more DCR messages, providing an acknowledgement (ACK) / negative acknowledgement (NACK) message to the RF interface for transmission to the second UE on the PSFCH, wherein the first reference signal and the first DCR message are associated with a same Tx beam of the one or more Tx beams of the second UE.

3. The baseband processor of claim 2, wherein the operations further comprise: providing the ACK / NACK message for transmission in a same slot as the beam reporting message using different frequency or code resources than the beam reporting message.

4. The baseband processor of claim 2, wherein the operations further comprise: providing the beam reporting message after the ACK / NACK message based on a(pre)configured time offset.

5. The baseband processor of claim 1 , wherein the operations further comprise providing the beam reporting message in response to one or more conditions being satisfied, the one or more conditions including at least one of: successfully decoding a first DCR message of the one or more DCR messages, wherein the first reference signal and the first DCR message are associated with a same Tx beam of the one or more Tx beams of the UE; a determination to establish a unicast connection with the second UE; or a measurement of the first reference signal exceeding a measurement threshold value.

6. The baseband processor of claim 1 , wherein the beam reporting message indicates an RSRP measurement of the first reference signal based on a codebook mapping, wherein the codebook mapping includes a mapping between RSRP measurement values and one or more of: frequency resources or code resources used for transmission of the beam reporting message.

7. The baseband processor of claim 1 , wherein the beam reporting message is provided in response to a first DCR message of the one or more DCR messages, and wherein a slot of the beam reporting message is based on a slot of the first DCR message.

8. The baseband processor of claim 1 , wherein the operations further comprise: determining the optimal Rx beam of the UE in response to the optimal Rx beam being associated with a highest RSRP measurement.

9. The baseband processor of claim 1 , wherein the beam reporting message is provided in response to a first DCR message of the one or more DCR messages, and wherein the operations further comprise: identifying a slot of the beam reporting message from a plurality of dedicated slots for beam reporting based on a slot of the first DCR message and an association rule; and providing the beam reporting message for transmission in the identified slot.

10. The baseband processor of claim 9, wherein the operations further comprise:receiving a resource pool (pre)configuration that configures the plurality of dedicated slots for beam reporting and the association rule.1 1 .The baseband processor of claim 9, wherein the operations further comprise: receiving sidelink control information (SCI) to schedule the first DCR message, wherein the SCI indicates the association rule.

12. The baseband processor of claim 1 , wherein the beam reporting message comprises a medium access control (MAC) control element (CE), the MAC CE including one or more of: a source identity (ID); a destination ID; a reference signal received power (RSRP) measurement of the first reference signal; or a sidelink channel state information reference signal (CSI-RS) resource ID.

13. The baseband processor of claim 1 , the beam reporting message comprises sidelink control information (SCI), the SCI including one or more of: a source identity (ID); a destination ID; a reference signal received power (RSRP) measurement of the first reference signal; or a sidelink channel state information reference signal (CSI-RS) resource ID.

14. The baseband processor of claim 1 , wherein the beam reporting message is provided in response to a first DCR message of the one or more DCR messages, and wherein the operations further comprise: receiving sidelink control information (SCI) to schedule the first DCR message, wherein the SCI indicates a first reference signal of the one or more reference signals associated with a same Tx beam of the second UE as the first DCR message, the first reference signal comprising a first sidelink channel state information reference signal (CSI-RS); identifying a slot of the beam reporting message from a plurality of dedicated slots for beam reporting based on a slot of the first CSI-RS and an association rule; and providing the beam reporting message for transmission in the identified slot.

15. A baseband processor for a user equipment (UE) configured to, when executing instructions stored in a memory, perform operations comprising: providing, to a radio frequency (RF) interface for transmission, one or more direct connection request (DCR) messages using a one or more respective transmit (Tx) beams; providing, to the RF interface, one or more reference signals using the one or more respective Tx beams; receiving, from a second UE, one or more beam reporting messages associated with one or more beams of the one or more Tx beams; identifying an optimal Tx beam for communication with the second UE based on the one or more beam reporting messages; and communicating with the second UE via the RF interface using the optimal Tx beam.

16. The baseband processor of claim 15, wherein the operations further comprise: identifying the optimal Tx beam in response to a beam reporting message associated with the optimal Tx beam being a most recently received beam reporting message of the one or more beam reporting messages.

17. The baseband processor of claim 15, wherein the one or more beam reporting messages indicate one or more reference signal received power (RSRP) measurements, and wherein the operations further comprise: identifying the optimal Tx beam in response to an RSRP measurement associated with the optimal Tx beam being a largest RSRP measurement indicated by the one or more beam reporting messages.

18. The baseband processor of claim 15, wherein the one or more reference signals comprise one or more sidelink channel state information reference signals (CSI-RSs), and wherein the operations further comprise: providing, to the RF interface for transmission, sidelink control information (SCI) to schedule a first DCR message of the one or more of DCR messages; wherein the SCI includes one or more of: a source identity (ID); a destination ID; a sidelink transmission configuration indicator (TCI) state;a sidelink CSI-RS resource ID of a first sidelink CSI-RS resource; time frequency resources of the first CSI-RS resource; or a periodicity of the first CSI-RS resource; wherein the first CSI-RS resource is associated with a same Tx beam as the first DCR message.

19. The baseband processor of claim 15, wherein the operations further comprise: providing, to the RF interface for transmission, a first DCR message of the one or more DCR messages using a first Tx beam of the one or more Tx beams; and monitoring for a first beam reporting message of the one or more beam reporting messages using a first Rx beam, wherein the first beam reporting message contains beam reporting information for the first Tx beam; wherein the first Rx beam is one of: the same as the first Tx beam, or derived from the first Tx beam.

20. A method to be performed by a user equipment (UE), comprising: receiving one or more direct connection request (DCR) messages from a second UE, wherein the one or more DCR messages are associated with one or more transmit (Tx) beams of the second UE respectively; receiving one or more reference signals from the second UE, the one or more reference signals associated with the one or more Tx beams of the second UE respectively; transmitting a beam reporting message to the second UE based on a first reference signal of the one or more reference signals; determining an optimal receive (Rx) beam of the UE for communication with the second UE based on the one or more reference signals; and communicating with the second UE using the optimal Rx beam.

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