Sidelink aperiodic channel state information reporting triggered by a base station

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

receiving, from a base station, a message that triggers aperiodic channel state information (CSI) reporting for sidelink communications between the UE and another UE, wherein the message indicates a first set of sidelink CSI reference signal (CSI-RS) resources to be used by the UE for CSI-RS transmission;

transmitting a first set of CSI-RSs in the first set of sidelink CSI-RS resources;

receiving an indication of one or more modulation and coding schemes (MCSs) for sidelink communications between the UE and the other UE based at least in part on transmitting the first set of CSI-RSs; and

communicating with the other UE using an MCS of the one or more MCSs.

2. The method of claim 1 , wherein the UE is a relay UE that relays communications between the base station and the other UE.

3. The method of claim 2 , further comprising receiving, from the base station, a communication to be relayed to the other UE; and

wherein communicating with the other UE comprises relaying the communication to the other UE via a sidelink communication that is modulated using the MCS.

4. The method of claim 2 , wherein communicating with the other UE comprises receiving, from the other UE, a communication to be relayed to the base station, wherein the communication is included in a sidelink communication that is modulated using the MCS; and

wherein the method further comprises relaying the communication to the base station.

5. The method of claim 1 , wherein the other UE is a relay UE that relays communications between the base station and the UE.

6. The method of claim 5 , wherein communicating with the other UE comprises receiving, from the other UE, a sidelink communication that includes a communication transmitted from the base station to the other UE, wherein the sidelink communication is modulated using the MCS.

7. The method of claim 5 , wherein communicating with the other UE comprises transmitting, to the other UE, a sidelink communication that includes a communication to be relayed to the base station by the other UE, wherein the sidelink communication is modulated using the MCS.

8. The method of claim 1 , wherein the indication of the one or more MCSs is received from the base station or is received from the other UE.

9. The method of claim 1 , further comprising receiving a sidelink aperiodic CSI report from the other UE based at least in part on transmitting the first set of CSI-RSs.

10. The method of claim 9 , further comprising transmitting the sidelink aperiodic CSI report to the base station.

11. The method of claim 1 , further comprising:

receiving, from the base station, an indication of a second set of sidelink CSI-RS resources to be used by the UE for CSI-RS measurement;

measuring the second set of CSI-RSs in the second set of sidelink CSI-RS resources; and

transmitting a sidelink aperiodic CSI report based at least in part on measuring the second set of CSI-RSs.

12. The method of claim 11 , wherein the sidelink aperiodic CSI report is transmitted to the base station.

13. The method of claim 12 , further comprising:

receiving an indication of an uplink resource in which the sidelink aperiodic CSI report is to be transmitted to the base station; and

wherein the sidelink aperiodic CSI report is transmitted to the base station using the uplink resource.

14. The method of claim 11 , wherein the sidelink aperiodic CSI report is transmitted to the other UE.

15. The method of claim 14 , further comprising:

receiving an indication of a sidelink resource in which the sidelink aperiodic CSI report is to be transmitted to the other UE; and

wherein the sidelink aperiodic CSI report is transmitted to the other UE using the sidelink resource.

16. The method of claim 11 , wherein the sidelink aperiodic CSI report and another sidelink aperiodic CSI report, received from the other UE, are both transmitted to the base station.

17. The method of claim 1 , wherein the message includes at least one of a sidelink identifier that identifies a sidelink between the UE and the other UE, a UE identifier that identifies the other UE, or a combination thereof.

18. The method of claim 1 , wherein the one or more MCSs include one of:

multiple MCSs or a range of MCSs, wherein the UE selects the MCS, from the multiple MCSs or the range of MCSs, to communicate with the other UE; or

a single MCS, wherein the single MCS is used to communicate with the other UE.

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

a memory; and

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

receive, from a base station, a message that triggers aperiodic channel state information (CSI) reporting for sidelink communications between the UE and another UE, wherein the message indicates a first set of sidelink CSI reference signal (CSI-RS) resources to be used by the UE for CSI-RS transmission;

transmit a first set of CSI-RSs in the first set of sidelink CSI-RS resources;

receive an indication of one or more modulation and coding schemes (MCSs) for sidelink communications between the UE and the other UE based at least in part on transmitting the first set of CSI-RSs; and

communicate with the other UE using an MCS of the one or more MCSs.

20. The UE of claim 19 , wherein the UE is a relay UE that relays communications between the base station and the other UE.

21. The UE of claim 20 , wherein the one or more processors are further configured to receive, from the base station, a communication to be relayed to the other UE; and

wherein the one or more processors, to communicate with the other UE, are configured to relay the communication to the other UE via a sidelink communication that is modulated using the MCS.

22. The UE of claim 20 , wherein communicating with the other UE comprises the one or more processors, to communicate with the other UE, are configured to receive, from the other UE, a communication to be relayed to the base station, wherein the communication is included in a sidelink communication that is modulated using the MCS; and

wherein the one or more processors are further configured to relay the communication to the base station.

23. The UE of claim 19 , wherein the other UE is a relay UE that relays communications between the base station and the UE.

24. The UE of claim 23 , wherein the one or more processors, to communicate with the other UE, are configured to receive, from the other UE, a sidelink communication that includes a communication transmitted from the base station to the other UE, wherein the sidelink communication is modulated using the MCS.

25. The UE of claim 23 , wherein the one or more processors, to communicate with the other UE, are configured to transmit, to the other UE, a sidelink communication that includes a communication to be relayed to the base station by the other UE, wherein the sidelink communication is modulated using the MCS.

26. A method of wireless communication performed by a base station, comprising:

transmitting, to a user equipment (UE), a message that triggers aperiodic channel state information (CSI) reporting for sidelink communications between the UE and another UE, wherein the message indicates a first set of sidelink CSI reference signal (CSI-RS) resources to be used by the UE for CSI-RS transmission;

receiving a sidelink aperiodic CSI report for sidelink communications between the UE and the other UE; and

transmitting, to at least one of the UE or the other UE, an indication of one or more modulation and coding schemes (MCSs) for sidelink communications between the UE and the other UE based at least in part on receiving the sidelink aperiodic CSI report.

27. The method of claim 26 , wherein the UE is a relay UE that relays communications between the base station and the other UE.

28. The method of claim 26 , wherein the other UE is a relay UE that relays communications between the base station and the UE.

29. The method of claim 26 , wherein receiving the sidelink aperiodic CSI report comprises at least one of receiving a first sidelink aperiodic CSI report from the UE, receiving a second sidelink aperiodic CSI report from the other UE, or a combination thereof.

30. A base station for wireless communication, comprising:

a memory; and

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

transmit, to a user equipment (UE), a message that triggers aperiodic channel state information (CSI) reporting for sidelink communications between the UE and another UE, wherein the message indicates a first set of sidelink CSI reference signal (CSI-RS) resources to be used by the UE for CSI-RS transmission;

receive a sidelink aperiodic CSI report for sidelink communications between the UE and the other UE; and

transmit, to at least one of the UE or the other UE, an indication of one or more modulation and coding schemes (MCSs) for sidelink communications between the UE and the other UE based at least in part on receiving the sidelink aperiodic CSI report.