Channel estimation for two-stage sidelink control using sidelink data channel DMRS

1. A method for wireless communications by a user equipment (UE), comprising:

transmitting one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports; and

transmitting a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of one or more antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission.

2. The method of claim 1 , wherein the first SCI and the second SCI are frequency division multiplexed (FDMed) in one or more symbols in a slot.

3. The method of claim 1 , further comprising providing an explicit indication in a first stage of the SCI of a number of layers of the second stage of the SCI.

4. The method of claim 1 , further comprising implicitly indicating a number of layers of the second stage of the SCI.

5. The method of claim 1 , wherein transmitting the second stage of the SCI comprises transmitting the second stage of the SCI using a single layer.

6. The method of claim 1 , wherein transmitting the second stage of the SCI comprises transmitting the second stage of the SCI using a number of layers equal to a number of layers used for the sidelink data channel transmission.

7. The method of claim 1 , wherein the transmissions on the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI are transmitted at a same power level or at power levels within a configured tolerance.

8. The method of claim 7 , wherein the same power level or the power levels within a configured tolerance comprise power levels resulting in reception of the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI at a same received power level or received power levels within the configured tolerance.

9. The method of claim 7 , further comprising selecting a precoder for the sidelink data channel and the second stage of the two-stage SCI to control the power level.

10. The method of claim 1 , wherein:

the sidelink data channel is precoded with a precoder; and

the method further comprises precoding the second stage of the two-stage sidelink control information (SCI) transmission using the precoder.

11. A method for wireless communications by a user equipment (UE), comprising:

receiving, on a sidelink channel, one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports;

receiving a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of one or more antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission; and

demodulating the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel transmission.

12. The method of claim 11 , wherein the first SCI and the second SCI are frequency division multiplexed (FDMed) in one or more symbols in a slot.

13. The method of claim 11 , wherein demodulating the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel comprises demodulating the second stage of the two-stage SCI using DMRSs received up to receiving an end of the second stage of the two-stage SCI.

14. The method of claim 11 , wherein demodulating the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel comprises demodulating the second stage of the two-stage SCI using DMRSs received up to an end of a slot in which the second stage of the two-stage SCI is received.

15. The method of claim 11 , further comprising flexibly determining the one or more DMRSs of the sidelink data channel to use for demodulating the second stage of the two-stage SCI.

16. The method of claim 11 , further comprising receiving an explicit indication in a first stage of the SCI of a number of layers used for the second stage of the SCI.

17. The method of claim 11 , wherein receiving the second stage of the SCI comprises receiving the second stage of the SCI using a single layer.

18. The method of claim 11 , wherein receiving the second stage of the SCI comprises receiving the second stage of the SCI using a number of layers equal to a number of layers used for the sidelink data channel transmission.

19. The method of claim 11 , wherein the transmissions on the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI are received at a same power level or at power levels within a configured tolerance.

20. The method of claim 11 , wherein:

the one or more DMRSs comprise DMRSs for a precoded sidelink data channel transmission; and

the method further comprises estimating the channel based on the DMRSs for the precoded sidelink data channel transmission, wherein the second stage of the two-stage SCI is demodulated based on the estimation.

21. An apparatus for wireless communications by a user equipment (UE), comprising:

a memory; and

at least one processor coupled with the memory and configured to:

transmit one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports, and

transmit a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of one or more antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission.

22. The apparatus of claim 21 , wherein the first SCI and the second SCI are frequency division multiplexed (FDMed) in one or more symbols in a slot.

23. The apparatus of claim 21 , wherein the processor is further configured to provide an explicit indication in a first stage of the SCI of a number of layers of the second stage of the SCI.

24. The apparatus of claim 21 , wherein the processor is further configured to implicitly indicate a number of layers of the second stage of the SCI.

25. The apparatus of claim 21 , wherein the apparatus is configured to transmit the second stage of the SCI by transmitting the second stage of the SCI using a single layer.

26. The apparatus of claim 21 , wherein the apparatus is configured to transmit the second stage of the SCI by transmitting the second stage of the SCI using a number of layers equal to a number of layers used for the sidelink data channel transmission.

27. The apparatus of claim 21 , wherein the transmissions on the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI are transmitted at a same power level or at power levels within a configured tolerance.

28. The apparatus of claim 27 , wherein the same power level or the power levels within a configured tolerance comprise power levels resulting in reception of the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI at a same received power level or received power levels within the configured tolerance.

29. The apparatus of claim 27 , wherein the processor is further configured to select a precoder for the sidelink data channel and the second stage of the two-stage SCI to control the power level.

30. The apparatus of claim 21 , wherein:

the sidelink data channel is precoded with a precoder; and

the processor is further configured to precode the second stage of the two-stage sidelink control information using the precoder.

31. An apparatus for wireless communications by a user equipment (UE), comprising:

a memory; and

at least one processor coupled with the memory and configured to:

receive, on a sidelink channel, one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports;

receive a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission; and

demodulate the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel transmission.

32. The apparatus of claim 31 , wherein the first SCI and the second SCI are frequency division multiplexed (FDMed) in one or more symbols in a slot.

33. The apparatus of claim 31 , wherein the processor is configured to demodulate the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel by demodulating the second stage of the two-stage SCI using DMRSs received up to receiving an end of the second stage of the two-stage SCI.

34. The apparatus of claim 31 , wherein the processor is configured to demodulate the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel by demodulating the second stage of the two-stage SCI using DMRSs received up to an end of a slot in which the second stage of the two-stage SCI is received.

35. The apparatus of claim 31 , wherein the processor is further configured to flexibly determine the one or more DMRSs of the sidelink data channel to use for demodulating the second stage of the two-stage SCI.

36. The apparatus of claim 31 , wherein the processor is further configured to receive an explicit indication in a first stage of the SCI of a number of layers used for the second stage of the SCI.

37. The apparatus of claim 31 , wherein the processor is configured to receive the second stage of the SCI by receiving the second stage of the SCI using a single layer.

38. The apparatus of claim 31 , wherein the processor is configured to receive the second stage of the SCI by receiving the second stage of the SCI using a number of layers equal to a number of layers used for the sidelink data channel transmission.

39. The apparatus of claim 31 , wherein the transmissions on the sidelink data channel, a first stage of the two-stage SCI, and the second stage of the two-stage SCI are received at a same power level or at power levels within a configured tolerance.

40. The apparatus of claim 31 , wherein:

the one or more DMRSs comprise DMRSs for a precoded sidelink data channel transmission, and

the processor is further configured to estimate the channel based on the DMRSs for the precoded sidelink data channel transmission, wherein the second stage of the two-stage SCI is demodulated based on the estimation.

41. An apparatus for wireless communications by a user equipment (UE), comprising:

means for transmitting one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports; and

means for transmitting a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission.

42. An apparatus for wireless communications by a user equipment (UE), comprising:

means for receiving, on a sidelink channel, one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports;

means for receiving a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission; and

means for demodulating the second stage of the two-stage SCI using the one or more DMRSs for the sidelink data channel.

43. A non-transitory computer-readable medium storing executable code thereon which, when executed by a processor, performs an operation for wireless communications by a user equipment (UE) comprising:

transmitting one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports; and

transmitting a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission.

44. A non-transitory computer-readable medium storing computer executable code thereon which, when executed by a processor, performs an operation for wireless communications by a user equipment (UE) comprising:

receiving one or more demodulation reference signals (DMRSs) for a sidelink data channel transmission via a set of one or more antenna ports;

code for receiving a second stage of a two-stage sidelink control information (SCI) transmission using antenna ports from the set of antenna ports, wherein:

the sidelink data channel transmission comprises a first physical sidelink shared channel (PSSCH) transmission; and

the two-stage SCI comprises:

a first SCI transmitted on a physical sidelink control channel (PSCCH) and carrying resource availability information; and

a second SCI transmitted on the PSSCH and carrying information to decode a data transmission; and

code for demodulating the second stage of the two-stage SCI using the one or more DMRS for the sidelink data channel.