Method and device for configuring SL HARQ RTT timer in NR V2X

1. A method for performing wireless communication by a first device, the method comprising:

obtaining a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer;

receiving, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH);

receiving, from the second device through the PSSCH, the second SCI and data;

determining a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and

starting the SL DRX retransmission timer.

2. The method of claim 1 , wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.

3. The method of claim 1 , wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received.

4. The method of claim 1 , wherein the value of the SL DRX retransmission timer and the value of the SL DRX HARQ RTT timer are configured per SL process.

5. The method of claim 1 , further comprising:

starting the SL DRX HARQ RTT timer in a slot following an end of reception of the PSSCH.

6. The method of claim 5 , wherein the SL DRX retransmission timer is started based on expiration of the SL DRX HARQ RTT timer.

7. The method of claim 1 , wherein, based on that (i) the information related to the next retransmission resource is not included in the first SCI and (ii) a physical sidelink feedback channel (PSFCH) resource is not configured, the value of the SL DRX HARQ RTT timer is determined as zero.

8. The method of claim 1 , wherein the first SCI includes information related to time resource assignment, and

wherein the information related to the time resource assignment includes only time information for the PSSCH.

9. The method of claim 1 , further comprising:

receiving, from a base station, information for determining the value of the SL DRX HARQ RTT timer as zero.

10. The method of claim 9 , wherein, based on (i) the first SCI not including the information related to the next retransmission resource and (ii) the information for determining the value of the SL DRX HARQ RTT timer as zero, the value of the SL DRX HARQ RTT timer is determined as zero.

11. The method of claim 10 , wherein the information for determining the value of the SL DRX HARQ RTT timer as zero is information related to a SL resource pool for which a PSFCH is not configured.

12. The method of claim 9 , wherein the information for determining the value of the SL DRX HARQ RTT timer as zero is received from the base station through a radio resource control (RRC) message.

13. The method of claim 1 , wherein a time during which the SL DRX retransmission timer is running is an active time of the first device.

14. A first device adapted to perform wireless communication, the first device comprising:

one or more memories storing instructions;

one or more transceivers; and

one or more processors connected to the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions to:

obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer;

control the one or more transceivers to receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH);

control the one or more transceivers to receive, from the second device through the PSSCH, the second SCI and data;

determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and

start the SL DRX retransmission timer.

15. The first device of claim 14 , wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.

16. The first device of claim 14 , wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received.

17. The first device of claim 14 , wherein the value of the SL DRX retransmission timer and the value of the SL DRX HARQ RTT timer are configured per SL process.

18. A processing device adapted to control a first device, the processing device comprising:

one or more processors; and

one or more memories operably connected to the one or more processors and storing instructions, wherein the one or more processors execute the instructions to:

obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer;

receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH);

receive, from the second device through the PSSCH, the second SCI and data;

determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and

start the SL DRX retransmission timer.

19. The processing device of claim 18 , wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.

20. The processing device of claim 18 , wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received.