Hybrid automatic repeat request feedback for a sidelink

1. A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

receive data or control signaling on one or more first sidelink channels on a first component carrier of a set of carriers;

receive data or control signaling on one or more second sidelink channels on a second component carrier of the set of carriers; and

transmit, on a designated set of component carriers, hybrid automatic repeat request (HARQ) feedback corresponding to the data or control signaling on the one or more first sidelink channels and the data or control signaling on the one or more second sidelink channels,

the designated set of component carriers including:

only the first component carrier, or

the second component carrier and one or more other component carriers.

2. The UE of claim 1 , wherein the HARQ feedback is based at least in part on a semi-static HARQ codebook.

3. The UE of claim 1 , wherein the HARQ feedback is associated with a fixed slot offset.

4. The UE of claim 3 , wherein the HARQ feedback is associated with one or more UE identifiers, one or more traffic cast types, and one or more resource pools, and wherein the HARQ feedback includes, for each source UE identifier and traffic cast type, X bits per carrier or per resource pool, where X is equal to a number of sidelink slots mapped to a feedback channel occasion in which the HARQ feedback is transmitted.

5. The UE of claim 1 , wherein the HARQ feedback is associated with a transmitter UE, wherein one or more slot offsets associated with the one or more first sidelink channels or the one or more second sidelink channels are set by the transmitter UE, and wherein the HARQ feedback includes, per carrier or per resource pool, N*Y bits, where Y is a maximum slot offset of the one or more slot offsets and N is an integer.

6. The UE of claim 5 , wherein Y is based at least in part on a number of sidelink slots that are available for sidelink communication.

7. The UE of claim 5 , wherein the one or more slot offsets are configured for the UE or the transmitter UE.

8. The UE of claim 1 , wherein the HARQ feedback includes one HARQ codebook per unicast link and one HARQ codebook per groupcast link of the UE.

9. The UE of claim 1 , wherein the HARQ feedback is based at least in part on a dynamic HARQ codebook.

10. The UE of claim 1 , wherein the HARQ feedback is based at least in part on sidelink assignment indicators (SAIs) included in transmissions on the one or more first sidelink channels and the one or more second sidelink channels.

11. The UE of claim 10 , wherein the SAIs are received via sidelink control information.

12. The UE of claim 10 , wherein the SAIs are tracked based at least in part on a source identifier associated with the SAIs.

13. A first user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

transmit, to a second UE, data or control signaling on one or more first sidelink channels on a first component carrier of a set of sidelink carriers;

transmit, to the second UE, data or control signaling on one or more second sidelink channels on a second component carrier of the set of sidelink carriers; and

receive, from the second UE and on a designated set of component carriers, hybrid automatic repeat request (HARQ) feedback corresponding to the data or control signaling on the one or more first sidelink channels and the data or control signaling on the one or more second sidelink channels,

the designated set of component carriers including:

only the first component carrier, or

the second component carrier and one or more other component carriers.

14. The first UE of claim 13 , wherein the HARQ feedback is based at least in part on a semi-static HARQ codebook.

15. The first UE of claim 13 , wherein the HARQ feedback is associated with a fixed slot offset.

16. The first UE of claim 15 , wherein the HARQ feedback is associated with one or more UE identifiers, one or more traffic cast types, and one or more resource pools, and wherein the HARQ feedback includes, for each source UE identifier and traffic cast type, X bits per carrier or per resource pool, where X is equal to a number of sidelink slots mapped to a feedback channel occasion in which the HARQ feedback is transmitted.

17. The first UE of claim 13 , wherein the one or more processors are further configured to:

set one or more slot offsets associated with the one or more first sidelink channels or the one or more second sidelink channels, wherein the HARQ feedback includes, per carrier or per resource pool, N*Y bits, where Y is a maximum slot offset of the one or more slot offsets and N is an integer.

18. The first UE of claim 17 , wherein Y is based at least in part on a number of sidelink slots that are available for sidelink communication.

19. The first UE of claim 17 , wherein the one or more slot offsets are configured for the first UE or the second UE.

20. The first UE of claim 13 , wherein the HARQ feedback includes one HARQ codebook per unicast link and one HARQ codebook per groupcast link of the second UE.

21. The first UE of claim 13 , wherein the HARQ feedback is based at least in part on a dynamic HARQ codebook.

22. The first UE of claim 13 , wherein the HARQ feedback is based at least in part on sidelink assignment indicators (SAIs) included in transmissions on the one or more first sidelink channels and the one or more second sidelink channels.

23. The first UE of claim 22 , wherein the one or more processors are further configured to:

transmit the SAIs via sidelink control information.

24. The first UE of claim 22 , wherein the SAIs are tracked based at least in part on one or more destination identifiers associated with the SAIs.

25. A method of wireless communication performed by a user equipment (UE), comprising:

receiving data or control signaling on one or more first sidelink channels on a first component carrier of a set of sidelink carriers;

receiving data or control signaling on one or more second sidelink channels on a second component carrier of the set of sidelink carriers; and

transmitting, on a designated set of component carriers, hybrid automatic repeat request (HARQ) feedback corresponding to the data or control signaling on the one or more first sidelink channels and the data or control signaling on the one or more second sidelink channels,

the designated set of component carriers including:

only the first component carrier, or

the second component carrier and one or more other component carriers.

26. The method of claim 25 , wherein the HARQ feedback is based at least in part on a semi-static HARQ codebook.

27. The method of claim 25 , wherein the HARQ feedback is based at least in part on a dynamic HARQ codebook.

28. A method of wireless communication performed by a first user equipment (UE), comprising:

transmitting, to a second UE, data or control signaling on one or more first sidelink channels on a first component carrier of a set of sidelink carriers;

transmitting, to the second UE, data or control signaling on one or more second sidelink channels on a second component carrier of the set of sidelink carriers; and

receiving, from the second UE and on a designated set of component carriers, hybrid automatic repeat request (HARQ) feedback corresponding to the data or control signaling on the one or more first sidelink channels and the data or control signaling on the one or more second sidelink channels,

the designated set of component carriers including:

only the first component carrier, or

the second component carrier and one or more other component carriers.

29. The method of claim 28 , wherein the HARQ feedback is based at least in part on a semi-static HARQ codebook.

30. The method of claim 28 , wherein the HARQ feedback is associated with a fixed slot offset.