Method for determining transmission beam in wireless communication system supporting sidelink, and terminal therefor

1. A method of determining a transmission beam by a first user equipment (UE) in a wireless communication system supporting sidelink, the method comprising:

selecting, by the first UE, a synchronization reference source;

receiving, by the first UE from the synchronization reference source, a SSB (Synchronization Signal Block) including a primary synchronization signal and a secondary synchronization signal;

receiving, by the first UE from the synchronization reference source, a plurality of SSBs each of which is repeated transmission of the SSB;

synchronizing to the synchronization reference source based on the SSB and the plurality of SSBs;

receiving, by the first UE from a second UE, a first sidelink signal;

determining a transmission resource for a second sidelink signal;

transmitting, by the first UE to the second UE, the second sidelink signal via the transmission resource,

receiving information on resources for the sidelink;

receiving measurement information related to a state of a channel for each for a plurality of antenna units;

transmitting channel state information reference signal (CSI-RS) based on the measurement information;

performing beam sweeping based on the plurality of antenna units for transmission to obtain measurement;

obtaining measurements for the beam sweeping;

receiving beam-related information from a second UE; and

determining the transmission beam and a transmission timing for the second sidelink signal based on the beam-related information included in the first sidelink signal and the measurements for the beam sweeping,

wherein the beam-related information comprises one or more preferred reception beams of the second UE and a reception timing of the second UE,

wherein the reception timing of the second UE includes a time resource corresponding to each of the one or more preferred reception beams among the resources,

wherein the one or more preferred reception beams are determined based on beam sweeping of the second UE, and

wherein the one or more preferred reception beams are indicated in an index form in which each index informs which beams, among reception sweeping beams by the second UE, belong to the one or more reception beams preferred by the second UE.

2. The method of claim 1 , further comprising:

transmitting a reference signal on each of a plurality of reference signal resources,

wherein the beam-related information is received from the second UE in response to the transmission of the reference signal, and

wherein the index form indicates one of the plurality of reference signal resources.

3. The method of claim 1 , wherein a time resource index is included within a predetermined valid time period.

4. The method of claim 1 , wherein the beam-related information further comprises a reference signal received power (RSRP) or a signal-to-noise ratio (SNR) measured by the second UE based on a reception beam with a beam index.

5. The method of claim 1 , wherein the beam-related information is received from the second UE in response to the beam sweeping of the first UE.

6. The method of claim 1 , wherein the reception of the beam-related information from the second UE comprises receiving the beam-related information from each of a plurality of second UEs, and wherein the determination of the transmission beam comprises determining a direction, a width, and a transmission time resource of a transmission beam for each of the plurality of second UEs.

7. The method of claim 6 , further comprising grouping the plurality of second UEs into a plurality of groups based on the beam-related information received from each of the plurality of second UEs, wherein signals for the plurality of groups are transmitted on different transmission time resources.

8. A first user equipment (UE) for determining a transmission beam in a wireless communication system supporting sidelink, the first UE comprising:

a transceiver; and

a processor connected to the transceiver,

wherein the processor is configured to:

control the transceiver to select a synchronization reference source, receive a SSB (Synchronization Signal Block) including a primary synchronization signal and a secondary synchronization signal from the synchronization reference source, receive a plurality of SSBs each of which is repeated transmission of the SSB from the synchronization reference source, synchronize to the synchronization reference source based on the SSB and the plurality of SSBs, receive a first sidelink signal from a second UE, determine a transmission resource for a second sidelink signal, transmit the second sidelink signal via the transmission resource to the second UE, receive information on resources for the sidelink, receive measurement information related to a state of a channel for each for a plurality of antenna units, and transmit channel state information reference signal (CSI-RS) based on the measurement information;

perform beam sweeping based on the plurality of antenna units for transmission to obtain measurement;

obtain measurements for the beam sweeping;

control the transceiver to receive beam-related information from a second UE; and

determine the transmission beam and a transmission timing for the second sidelink signal based on the beam-related information included in the first sidelink signal and the measurements for the beam sweeping,

wherein the beam-related information comprises one or more preferred reception beams of the second UE and a reception timing of the second UE,

wherein the reception timing of the second UE includes a time resource corresponding to each of the one or more preferred reception beams among the resource,

wherein the one or more preferred reception beams are determined based on beam sweeping of the second UE, and

wherein the one or more preferred reception beams are indicated in an index form in which each index informs which beams, among reception sweeping beams by the second UE, belong to the one or more reception beams preferred by the second UE.

9. The first UE of claim 8 , wherein the processor is configured to:

control the transceiver to transmit a reference signal on each of a plurality of reference signal resources; and

control the transceiver to receive the beam-related information from the second UE in response to the transmission of the reference signal, and

wherein the index form indicates one of the plurality of reference signal resources.

10. The first UE of claim 8 , wherein a time resource index is included within a predetermined valid time period.

11. The first UE of claim 8 , wherein the beam-related information further comprises a reference signal received power (RSRP) or a signal-to-noise ratio (SNR) measured by the second UE based on a reception beam with a beam index.

12. The first UE of claim 8 , wherein the processor is configured to control the transceiver to receive the beam-related information from the second UE in response to the beam sweeping performed by the first UE.

13. The first UE of claim 8 , wherein the processor is configured to:

control the transceiver to receive the beam-related information from each of a plurality of second UEs; and

determine a direction, a width, and a transmission time resource of a transmission beam for each of the plurality of second UEs.

14. The first UE of claim 13 , wherein the processor is configured to:

group the plurality of second UEs into a plurality of groups based on the beam-related information received from each of the plurality of second UEs; and

control the transceiver to transmit signals for the plurality of groups on different transmission time resources.