FIG. 2.

Referring to FIG. 2, UE 102 can have antenna panel 117 including one or more antenna elements to form various beams, e.g., beam 122, beam 124, or beam 126, coupled to transceiver 131 and controlled by processor 133. Transceiver 131 and antenna panel 117 can be configured to enable wireless communication in a wireless network, such as wireless network 100, including wireless communication with UE 108 and base station 101. In detail, transceiver 113 can include radio frequency (RF) circuitry 216, transmission circuitry 212, and reception circuitry 214 to enable wireless communication with other UEs and/or a base station as discussed for wireless network 100. RF circuitry 216 can include multiple parallel RF chains for one or more of transmit or receive functions, each connected to one or more antenna elements of the antenna panel. In addition, processor 133 can be communicatively coupled to a memory 201, which are further coupled to the transceiver 131. Various data can be stored in memory 201.

In some examples, memory 201 can store one or more sidelink reference signals 141, message 143, or signal strength measurements 144. Memory 201 can store the set of beam patterns 142 to be used in a beam pairing procedure. The set of beam patterns 142 can include one or more transmission beams of the UE, and one or more receiving beams of the receiver UE. As shown in FIG. 1, UE 102 can generate beam 122, beam 124, beam 126, and UE 108 can generate beam 151, beam 153, and beam 155. In theory, there could be 3*3 different beam pairs for data communication between UE 102 and UE 108. However, the number of beams is not limited to this 3*3 construct. A transmission beam can be selected from beam 122, beam 124, and beam 126, while a receiving beam can be selected from beam 151, beam 153, and beam 155. The total 3*3=9 possible pairs of a transmission beam and a receiving beam can be represented as A={(122, 151), (124, 151), (126, 151), (122, 153), (124, 153), (126, 153), (122, 155), (124, 155), (126, 155)}. To reduce the candidates for the selection of a pair of a transmission beam and a receiving beam, the set of beam patterns 142 can be a subset of the set of all possible pairs of a transmission beam and a receiving beam. For example, the set of beam patterns 142 can be subset B={(122, 151), (124, 151), (122, 155), (124, 155), (126, 155)}, which is a subset of all possible beam patterns A. Since the set of beam patterns 142 may be smaller than all the possible N*M beam pairs, the efficiency for the selection of the beam pair can be improved.

Based on the discussion herein, it will apparent that the other UEs 103, 104, 106, and 108 in FIG. 1 can have a same or similar structure to that described for UE 102 in FIG. 2.

In some embodiments, memory 201 can store instructions, that when executed by processor 133 perform or cause to perform operations described herein, e.g., operations to perform a beam pairing procedure for sidelink communications. Alternatively, processor 133 can be “hard-coded” to perform the operations described herein. In some embodiments, processor 133 can be configured to perform operations described for FIG. 3A when UE 102 functions as a transmission UE or FIG. 3B when UE 102 functions as a receiver UE, as will be understood by one skilled in the art.

FIGS. 3A-3B illustrate example process 310 and process 320 performed by a transmission UE and a receiver UE to perform a beam pairing procedure for sidelink communications, according to some aspects of the disclosure. Process 310 and process 320 can be performed by UE 102, UE 104, UE 106, or UE 108, which may be implemented as shown in FIG. 2. Process 310 and process 320 may also be performed by a computer system 700 of FIG. 7. Process 310 and process 320 are not limited to the specific aspects depicted in those figures and other systems may be used to perform the method as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown in process 310 and process 320.

Process 310 shown in FIG. 3A describes operations performed by UE 102 when UE 102 functions as a transmission UE, where data communication is transmitted from the transmission UE to a receiver UE such as UE 108.

At 312, processor 133 of UE 102 can configure the set of beam patterns 142 to be used in a beam pairing procedure. For example, the set of beam patterns 142 can be C={(122, 151), (124, 151), (122, 155), (124, 155)}. The set C includes one or more transmission beams of UE 102 (beam 122 and beam 124), and one or more receiving beams (beam 151 and beam 155) of UE 108.

At 314, processor 133 of UE 102 can transmit, using one or more beam patterns of the set of beam patterns, the one or more sidelink reference signals 141 to the receiver UE. In some examples, the one or more sidelink reference signals 141 can include a sidelink channel state information reference signal (CSR-RS). In some examples, the one or more sidelink reference signals 141 can be carried using a physical sidelink shared channel (PSSCH) that carries data information. In some examples, UE 102 can further be configured to receive a beam pairing request from the receiver UE before transmitting the one or more sidelink reference signals 141 to the receiver UE.

At 316, processor 133 of UE 102 can receive message 143 from the receiver UE, which can be UE 108. Message 143 may contain information related to signal strength measurements 144 on the one or more beam patterns based on the one or more sidelink reference signals 141. The signal strength measurements 144 performed on the one or more beam patterns based on the one or more sidelink reference signals 141 can include a Reference Signal Receive Power (RSRP) measurement, a Reference Signal Received Quality (RSRQ), or a Signal to Interference & Noise Ratio (SINR).

At 318, based on the received message 143, processor 133 of UE 102 can further determine a selected transmission beam selected from the one or more transmission beams of UE 102 for signal transmissions from UE 102 to the receiver UE. For example, processor 133 can determine the selected transmission beam to be beam 122 based on one or more transmission beams of UE 102 defined by the set of beam patterns C={(122, 151), (124, 151), (122, 155), (124, 155)}. In some examples, the receiver UE 108 can make a selection for the selected transmission beam, and message 143 received from the receiver UE 108 can contain an identifier of the selected transmission beam selected by the receiver UE 108. In such a situation, processor 133 can determine the selected transmission beam by reading the identifier of the selected transmission beam contained in message 143.

At step 319, processor 133 can transmit data from UE 102 to UE 108 using the selected transmission beam 122.

It will be understood that the transmit and receive operations discussed herein for process 310 can be enabled at least in part by transceiver 131 and/or antenna panel 117.

In some embodiments, to determine the selected transmission beam, processor 133 can select the selected transmission beam of UE 102 and a related receiving beam of the receiver UE based on the information related to the signal strength measurements on the one or more beam patterns based on the one or more sidelink reference signals. Afterwards, processor 133 can transmit an indication to the receiver UE 108 to indicate the selected transmission beam and the related receiving beam of the receiver UE 108. The indication to indicate the selected transmission beam and the related receiving beam includes a quasi-co-location (QCL) indication.

Process 320 shown in FIG. 3B describes operations performed by a receiver UE such as UE 108, where data communication is transmitted from a transmission UE such as UE 102 to UE 108.

At 322, processor 137 of UE 108 can configure the set of beam patterns 142 to be used in a beam pairing procedure, where the set of beam patterns 142 is the same set of beam patterns used to configure the transmission UE such as UE 102.

At 324, processor 137 of UE 108 can receive one or more sidelink reference signals 141 from transmission UE 102. The one or more sidelink reference signals 141 may be carried by a PSSCH that carries data information. In some examples, the one or more sidelink reference signals includes a sidelink (SL) channel state information reference signal (CSR-RS). In some examples, processor 137 of UE 108 can transmit a beam pairing request to the transmission UE 102 before receiving the one or more sidelink reference signals 141 from the transmission UE 102. The transmitting the beam pairing request to the transmission UE 102 can be triggered by a timer or an event, and the beam pairing request can be contained in a MAC CE or in SCI stage 2.

At 326, processor 137 of UE 108 can perform signal strength measurements 144 on the one or more beam patterns based on the one or more sidelink reference signals 141. The signal strength measurements 144 of the one or more sidelink reference signals 141 can include a RSRP measurement, a RSRQ measurement, or a SINR measurement.

At 328, processor 137 of UE 108 can transmit message 143 to the transmission UE 102. Message 143 may contain information related to the signal strength measurements 144 of the one or more sidelink reference signals 141. In some examples, message 143 may be transmitted by a physical sidelink feedback channel (PSFCH).

In some examples, processor 137 of UE 108 can further determine a selected transmission beam selected from the one or more transmission beams of the transmission UE 102. In such examples, message 143 transmitted to the transmission UE 102 can contain an identifier of the selected transmission beam. The identifier of the selected transmission beam can include a slot index, or a resource identifier of the one or more sidelink reference signals.

At 329, processor 137 of UE 108 can determine a selected receiving beam selected from the one or more receiving beams of the UE for receiving signal transmissions from the transmission UE. In some examples, UE 108 can make the selection to determine the selected receiving beam. In some other examples, the transmission UE 102 can make the selection to determine the selected receiving beam. Accordingly, UE 108 can receive a message from the transmission UE 102 that includes an indication of the selected receiving beam selected from the one or more receiving beams of the UE by the transmission UE 102.

At 330, processor 137 of UE 108 can receive data from the transmission UE 102 using the selected receiving beam.

It will be understood that the transmit and receive operations discussed herein for process 320 can be enabled at least in part by transceiver 135 and/or antenna panel 119.

FIGS. 4A-4B illustrate example process 410 and process 420 performed by a transmission UE and a receiver UE for a beam pairing procedure for sidelink communications, according to some aspects of the disclosure.

As shown in FIG. 4A, process 410 can be an implementation and example of process 310, which can be performed by a transmission UE such as UE 102.

At 412, processor 133 of UE 102 can configure the set of beam patterns 142 to be used in a beam pairing procedure with a receiver UE. Operations performed at 412 can be examples of operations performed at 312. The configuration of the set of beam patterns 142 may include configuring various parameters such as a total number of beam transmissions for beam pairing, initial transmission and retransmission, a time window of the beam pairing procedure, and the set of beam pairs to be used in the beam pairing procedure. For example, transport block 1 (TB1) transmission can initially be transmitted with beam 122, and TB1 retransmission can be transmitted with beam 124; transport block 2 (TB2) transmission can initially be transmitted with beam 124, and TB2 retransmission can be transmitted with the same beam 124; TB1 initial transmission and retransmission are both transmitted with beam 122; TB2 initial transmission and retransmission are both transmitted with beam 124; TB1 initial transmission can be transmitted by both beam 122 and beam 124, and TB1 retransmission can be transmitted with beam 124 and beam 126.

At 414, processor 133 of UE 102 can transmit one or more sidelink reference signals by PSSCH with different transmission beams to the receiver UE. Operations performed at 414 can be examples of operations performed at 314. The PSSCH can include SL CSI-RS for RSRP measurement, SCI to indicate the start of the beam pairing procedure. In addition, dummy PSSCH may be used for the beam pairing. The transmission of PSSCH with different beams may be triggered by various mechanisms. For example, PSSCH transmission can be triggered periodically, based on a request from a base station, or based on a detection of an existence of a receiver UE.

At 416, processor 133 of UE 102 can receive from the receiver UE the indicated paired transmission beam identifier (ID) for the transmission beam. Operations performed at 416 can be examples of operations performed at 316 and 318, where the message received contains the ID of the transmission beam. The selection of the transmission beam of UE 102 can be performed by the receiver UE 108. If no transmission beam ID is received from the receiver UE within a certain time, UE 102 can retransmit the one or more sidelink reference signals by PSSCH to the receiver UE. Retransmission of the PSSCH could have same set of beams or different sets of beams from the initial PSSCH transmissions. Certain time gap may be introduced between the PSSCH transmission and PSSCH retransmission for beam pairing.

At 419, processor 133 of UE 102 can transmit a PSSCH data transmission to the receiver UE using the indicated transmission beam ID for the PSSCH data transmission. Optionally, UE 102 may send an acknowledgement (ACK) to the receiver UE 108 to confirm the reception of the transmission beam ID indication from the receiver UE 108.

It will be understood that the transmit and receive operations discussed herein for process 410 can be enabled at least in part by transceiver 131 and/or antenna panel 117.

As shown in FIG. 4B, process 420 can be an implementation or an example of process 320, which can be performed by a receiver UE such as UE 108.

At 422, processor 137 of UE 108 can configure the set of beam patterns 142 to be used in a beam pairing procedure with a transmission UE such as UE 102. Operations performed at 422 can be examples of operations performed at 322, with details described similarly as operations performed at 412 by the transmission UE.

At 424, processor 137 of UE 108 can receive one or more sidelink reference signals carried by PSSCH with different receiving beams from the transmission UE such as UE 102. Operations performed at 424 can be examples of operations performed at 324, with details described similarly as operations performed at 414 by the transmission UE.

At 426, to measure the strength of different transmission beams, processor 137 of UE 108 can perform signal strength measurements 144 of the one or more sidelink reference signals 141. Operations performed at 426 can be examples of operations performed at 326 and at 328. If more than one retransmission uses the same transmission beam, then the averaged RSRP measurement or the later in time RSRP measurement is used for the transmission beam. In some embodiments, PSSCH RSRP or PSCCH RSRP can be measured. In addition, UE 108 can make the selection of the selected transmission beam based on the signal strength measurements 144 on various transmission beams. The selection can be based on configuration, such as resource pool (pre)configuration or PC5-RRC configuration between a pair of UEs.

In some embodiments, processor 137 of UE 108 can further transmit message 143 to the transmission UE 102 to report the selected transmission beam for the UE 102. The message 143 can include various contents. In some embodiments, message 143 can include only the transmission beam ID corresponding to the strongest RSRP (or SINR) measured by UE 108, without a separate RSRP measurement reporting, such as per beam or per PSSCH transmission. The transmission beam ID may be represented by the order of the PSSCH transmission, or represented by the slot index of the corresponding PSSCH transmission (with the strongest RSRP value). Additionally and alternatively, the transmission beam ID may be represented by the CSI-RS resource ID. In some embodiments, message 143 can include multiple transmission beam ID whose signal strength measurements may be stronger than a threshold and which corresponds to the same receiver beam.

In some embodiments, message 143 can be transmitted by a PSFCH transmission corresponding to the last PSCCH/PSSCH transmission for the beam pairing procedure. The PSFCH transmission priority can be (pre)configured per resource pool or based on SL beam pairing configuration. The PSFCH transmission for beam pairing may have a higher priority than PSFCH for SL HARQ or inter-UE coordination. The PSFCH transmission for beam pairing may have a lower priority than PSFCH for SL HARQ or inter-UE coordination. In some embodiments, message 143 can be transmitted by a PSCCH/PSSCH transmission. The PSCCH/PSSCH transmission may follow a legacy resource selection procedure, and packet delay budget (PDB) may be (pre)configured per resource pool or based on SL beam pairing configuration. Similarly, data priority may be (pre)configured per resource pool or based on SL beam pairing configuration.

At 429, processor 137 of UE 108 can receive data using the receiving beam corresponding to the reported transmission beam contained in message 143. In some embodiments, the receiver UE 108 does not need to be informed by the transmission UE 102 for the paired beam, UE 108 can autonomously receive data using the receiving beam corresponding to the reported transmission beam. UE 108 may receive data using the receiving beam at a time instance of some offset after sending the message 143 to UE 102. The offset may be pre-defined or (pre)configured per resource pool or configured during PC5-RRC configuration. In some other embodiments, UE 108 may receive data using the receiving beam corresponding to the reported transmission beam contained in message 143 after receiving an acknowledgement (ACK) message for message 143 to indicate that message 143 has been received. The ACK message can be a SCI stage 2 message to indicate the reception of beam reporting message 143 by UE 102. Additionally and alternatively, the ACK message can be a MAC CE message to indicate the reception of beam reporting message 143 by UE 102. Furthermore, in some embodiments, the ACK message can be sent based on a timer ACK for CG-PUSCH. In some embodiments, a time gap may be applied between beam reporting message 143 being sent and the use of the corresponding receiving beam by UE 108. If the message 143 is sent by a PSSCH transmission, the ACK message to the PSSCH transmission of message 143 can be the slot to receive data using the receiving beam corresponding to the reported transmission beam contained in message 143.

It will be understood that the transmit and receive operations discussed herein for process 420 can be enabled at least in part by transceiver 135 and/or antenna panel 119.

FIGS. 5A-5B illustrate example process 510 and process 520 performed by a transmission UE and a receiver UE for a beam pairing procedure for sidelink communications, according to some aspects of the disclosure.

As shown in FIG. 5A, process 510 can be an implementation of process 310. Previously, process 410 in FIG. 4A shows the one or more sidelink reference signals by PSSCH are sent by the transmission UE 102 without being triggered by a receiving UE. Alternatively, process 510 shows the one or more sidelink reference signals carried by PSSCH are triggered by a request from the receiver UE 108.

At 512, processor 133 of UE 102 can configure the set of beam patterns 142 to be used in a beam pairing procedure. Operations performed at 512 can be examples of operations performed at 312. Details of operations performed at 512 can be similar to details of operations performed at 412.

At 513, processor 133 of UE 102 can receive a beam pairing request from a receiver UE. The request can trigger the transmission UE to send multiple sidelink reference signals repeatedly transmitted with different transmission beams. The beam pairing request can be sent via a SCI stage 2 message, or a MAC CE. The beam pairing request may be triggered based on some events or timer. For example, the beam pairing request may be triggered when several continuous PSSCH decoding failures are detected, when the receiver UE wants to set up the sidelink connection with the transmission UE, when the receiver UE has some sidelink data to be sent to the transmission UE where data priority is higher than a threshold, or some other events.

At 514, processor 133 of UE 102 can transmit, one or more sidelink reference signals by PSSCH with different transmission beams. Operations performed at 514 can be examples of operations performed at 314 with details similar to the details described for operations performed at 414.

At 516, processor 133 of UE 102 can receive from the receiver UE the indicated paired beam ID for the transmission beam. Operations performed at 416 can be examples of operations performed at 316 and 318, where the message received contains the ID of the transmission beam. Operations performed at 516 can have details similar to the details described for operations performed at 416 by the transmission UE 102.

At 519, processor 133 of UE 102 can transmit a PSSCH data transmission to the receiver UE using the indicated transmission beam ID for the PSSCH data transmission. Operations performed at 519 can have details similar to the details described for operations performed at 419 by the transmission UE 102.

It will be understood that the transmit and receive operations discussed herein for process 510 can be enabled at least in part by transceiver 131 and/or antenna panel 117.

As shown in FIG. 5B, process 520 can be an implementation of process 320, which can be performed by a receiver UE such as UE 108. Process 520 shows the one or more sidelink reference signals carried by PSSCH are triggered by a request from the receiver UE 108.

At 522, processor 137 of UE 108 can configure the set of beam patterns 142 to be used in a beam pairing procedure. Operations performed at 522 can be examples of operations performed at 322. Details of operations performed at 522 can be similar to details of operations performed at 422.

At 523, processor 137 of UE 108 can send the beam pairing request to the transmission UE to trigger the transmission UE sending multiple signals repeatedly with different transmission beams. The beam pairing request may be triggered based on some events or timer. For example, the beam pairing request may be triggered when several continuous PSSCH decoding failures are detected, when the receiver UE wants to set up the sidelink connection with the transmission UE, when the receiver UE has some sidelink data to be sent to the transmission UE where data priority is higher than a threshold, or some other events. The beam pairing request can be sent via a SCI stage 2 message, or a MAC CE. The content of the beam pairing request can include the beam patterns to be used to transmit one or more sidelink reference signals, beam pairing starting time, and other parameters. The beam pairing request can have a priority (pre)configured per resource pool.

At 524, processor 137 of UE 108 can receive the one or more sidelink reference signals carried by PSSCH with different transmission beams from the transmission UE. Operations performed at 524 can be examples of operations performed at 324 with details similar to the details described for operations performed at 424.

At 526, processor 137 of UE 108 can perform signal strength measurements 144 of the one or more sidelink reference signals 141, and can further transmit message 143 to the transmission UE 102 to report the selected transmission beam for the UE 102. Operations performed at 526 can be examples of operations performed at 326 and 328, with details similar to the details described for operations performed at 426.

At 529, processor 137 of UE 108 can receive data communication from transmission UE 102 using the receiving beam corresponding to the reported transmission beam contained in message 143. Operations performed at 529 can have details similar to the details described for operations performed at 429.

It will be understood that the transmit and receive operations discussed herein for process 520 can be enabled at least in part by transceiver 135 and/or antenna panel 119.

FIGS. 6A-6B illustrate example process 610 and process 620 performed by a transmission UE and a receiver UE for a beam pairing procedure for sidelink communications, according to some aspects of the disclosure.

As shown in FIG. 6A, process 610 can be an implementation of process 310. Previously, in process 410 and process 510, the receiver UE 108 makes the selection of the transmission beam and sends message 143 to transmission UE 102 to indicate the selected transmission beam. Alternatively, process 610 shows the operations performed by transmission UE 102 to make the selection of the transmission beam and potentially the corresponding receiving beam for receiver UE 108.

At 612, processor 133 of UE 102 can configure the set of beam patterns 142 to be used in a beam pairing procedure with a receiver UE. Operations performed at 612 can be examples of operations performed at 312.

At 614, processor 133 of UE 102 transmits one or more sidelink reference signals by PSSCH with different transmission beams to the receiver UE. Operations performed at 614 can be examples of operations performed at 314.

At 616, processor 133 of UE 102 can receive from the receiver UE 108 message 143 containing information related to signal strength measurements on the one or more beam patterns based on the one or more sidelink reference signals. In some example, the receiver UE 108 performs signal strength measurements such as L1-RSRP or L1-SINR measurements. Operations performed at 616 can be examples of operations performed at 316.

At 618A, processor 133 of UE 102 can perform the transmission beam selection to include a Quasi-co-location (QCL) indication. In some embodiments, processor 133 of UE 102 can determine the transmitting beam corresponding to the highest beam strength in the reported beam strengths. In some embodiments, processor 133 of UE 102 can also determine the receiving beam of the receiver UE