Feedback process in multicast retransmission

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

receiving a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a first feedback process identifier associated with the multicast data message;

receiving a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating a second feedback process identifier associated with the unicast downlink shared channel and that is different from the first feedback process identifier;

receiving an indication that the second feedback process identifier is associated with the first feedback process identifier; and

transmitting feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the second feedback process identifier being associated with the first feedback process identifier.

2. The method of claim 1 , further comprising:

receiving the unicast downlink shared channel after a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, the receiving of the unicast downlink shared channel being in accordance with a retransmission timing rule.

3. The method of claim 2 , wherein the retransmission timing rule is indicative that the unicast downlink shared channel is to be received after an end of the first scheduled feedback message based at least in part on the second feedback process identifier being associated with the first feedback process identifier.

4. The method of claim 1 , further comprising:

receiving the unicast downlink shared channel before a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, the receiving of the unicast downlink shared channel being in accordance with a retransmission timing rule.

5. The method of claim 4 , wherein the retransmission timing rule specifies that the unicast downlink shared channel is receivable before the first scheduled feedback message, even when the second feedback process identifier is associated with the first feedback process identifier.

6. The method of claim 4 , further comprising:

decoding either the multicast data message or the retransmission of the multicast data message without soft-combining decoding results from the multicast data message and the retransmission of the multicast data message, wherein transmitting the feedback is based on decoding only one of the multicast data message or the retransmission of the multicast data message.

7. The method of claim 6 , wherein transmitting the feedback pertaining to at least one of the multicast downlink shared channel or the unicast downlink shared channel further comprises:

transmitting the feedback via either the first scheduled feedback message corresponding to the multicast data message or a second scheduled feedback message corresponding to the retransmission of the multicast data message.

8. The method of claim 7 , wherein transmitting the feedback via either the first scheduled feedback message or the second scheduled feedback message further comprises:

transmitting the feedback via the second scheduled feedback message and either not transmitting the first scheduled feedback message or transmitting the first scheduled feedback message with invalid feedback.

9. The method of claim 1 , wherein receiving the indication that the second feedback process identifier is associated with the first feedback process identifier comprises:

receiving the indication via either a radio resource control message, the first downlink control information message, the second downlink control information message, or a medium access control-control element.

10. The method of claim 1 , wherein the unicast downlink shared channel is scheduled to be received without overlap of the multicast downlink shared channel, in accordance with a scheduling rule that prohibits overlap of multiple downlink transmissions associated with a same feedback process identifier.

11. The method of claim 1 , wherein transmitting the feedback pertaining to at least one of the multicast downlink shared channel or the unicast downlink shared channel further comprises:

transmitting the feedback via at least one of a first scheduled feedback message corresponding to the multicast data message or a second scheduled feedback message corresponding to the retransmission of the multicast data message, wherein the second scheduled feedback message is scheduled to be transmitted after transmission of the first scheduled feedback message in accordance with a scheduling rule that prohibits transmission of the second scheduled feedback message prior to transmission of the first scheduled feedback message.

12. The method of claim 1 , wherein the retransmission of the multicast data message is scheduled to be received after a last symbol of the multicast data message, in accordance with a scheduling rule that prohibits scheduling the retransmission of the multicast data message to begin prior to the last symbol of the multicast data message when the second downlink control information message is received after the first downlink control information message.

13. The method of claim 1 , wherein

the retransmission of the multicast data message is scheduled to be received at least a threshold number of symbols after a last symbol of a system information message, in accordance with a scheduling rule that prohibits scheduling a retransmission within less than the threshold number of symbols after the last symbol of the system information message,

the threshold number of symbols is based at least in part on a subcarrier spacing configuration.

14. A method for wireless communications at a user equipment (UE), comprising:

receiving a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a feedback process identifier associated with the multicast data message;

receiving a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating the feedback process identifier as being associated with the unicast downlink shared channel; and

transmitting feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the feedback process identifier being associated with both the multicast data message and the retransmission of the multicast data message.

15. The method of claim 14 , further comprising:

receiving the unicast downlink shared channel after a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, the receiving of the unicast downlink shared channel being in accordance with a retransmission timing rule.

16. The method of claim 15 , wherein the retransmission timing rule is indicative that the unicast downlink shared channel is to be received after the first scheduled feedback message based at least in part on the feedback process identifier being associated with both the multicast downlink shared channel and the unicast downlink shared channel.

17. A method for wireless communications at a base station, comprising:

transmitting, to a user equipment (UE), a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a first feedback process identifier associated with the multicast data message;

transmitting a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating a second feedback process identifier to be associated with the unicast downlink shared channel and that is different from the first feedback process identifier;

transmitting an indication that the second feedback process identifier is associated with the first feedback process identifier; and

receiving, from the UE, feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the second feedback process identifier being associated with the first feedback process identifier.

18. The method of claim 17 , further comprising:

transmitting the unicast downlink shared channel after a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, transmission of the unicast downlink shared channel being in accordance with a retransmission timing rule.

19. The method of claim 18 , wherein the retransmission timing rule is indicative that the unicast downlink shared channel is to be transmitted after an end of the first scheduled feedback message based at least in part on the second feedback process identifier being associated with the first feedback process identifier.

20. The method of claim 17 , further comprising:

transmitting the unicast downlink shared channel before a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, transmission of the unicast downlink shared channel being in accordance with a retransmission timing rule.

21. The method of claim 20 , wherein the retransmission timing rule specifies that the unicast downlink shared channel is receivable before the first scheduled feedback message, even when the second feedback process identifier is associated with the first feedback process identifier.

22. The method of claim 20 , wherein receiving the feedback pertaining to at least one of the multicast downlink shared channel or the unicast downlink shared channel further comprises:

receiving the feedback via either the first scheduled feedback message corresponding to the multicast data message or a second scheduled feedback message corresponding to the retransmission of the multicast data message.

23. The method of claim 22 , wherein receiving the feedback via either the first scheduled feedback message or the second scheduled feedback message further comprises:

receiving the feedback via the second scheduled feedback message and either not receiving the first scheduled feedback message or receiving the first scheduled feedback message with invalid feedback.

24. The method of claim 17 , wherein transmitting the indication that the second feedback process identifier is associated with the first feedback process identifier comprises:

transmitting the indication via either a radio resource control message, the first downlink control information message, the second downlink control information message, or a medium access control-control element.

25. The method of claim 17 , wherein the retransmission of the multicast data message is scheduled to be transmitted without overlap of the multicast data message, in accordance with a scheduling rule that prohibits overlap of multiple downlink transmissions associated with a same feedback process identifier.

26. The method of claim 17 , wherein receiving the feedback pertaining to at least one of the multicast downlink shared channel or the unicast downlink shared channel further comprises:

receiving the feedback via at least one of a first scheduled feedback message corresponding to the multicast data message or a second scheduled feedback message corresponding to the retransmission of the multicast data message, wherein the second scheduled feedback message is scheduled to be received after reception of the first scheduled feedback message in accordance with a scheduling rule that prohibits reception of the second scheduled feedback message prior to reception of the first scheduled feedback message.

27. The method of claim 17 , wherein the retransmission of the multicast data message is scheduled to be transmitted after a last symbol of the multicast data message, in accordance with a scheduling rule that prohibits scheduling the retransmission of the multicast data message to begin prior to the last symbol of the multicast data message when the second downlink control information message is transmitted after the first downlink control information message.

28. The method of claim 17 , wherein

the retransmission of the multicast data message is scheduled to be transmitted at least a threshold number of symbols after a last symbol of a system information message, in accordance with a scheduling rule that prohibits scheduling a retransmission within less than the threshold number of symbols after the last symbol of the system information message,

the threshold number of symbols is based at least in part on a subcarrier spacing configuration.

29. A method for wireless communications at a base station, comprising:

transmitting, to a user equipment (UE), a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a feedback process identifier associated with the multicast data message;

transmitting a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating the feedback process identifier as being associated with the unicast downlink shared channel; and

receiving feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the feedback process identifier being associated with both the multicast data message and the retransmission of the multicast data message.

30. The method of claim 29 , further comprising:

transmitting the unicast downlink shared channel after a first scheduled feedback message corresponding to the multicast data message is scheduled to be transmitted, the transmitting of the unicast downlink shared channel being in accordance with a retransmission timing rule.

31. The method of claim 14 , further comprising:

decoding either the multicast data message or the retransmission of the multicast data message without soft-combining decoding results from the multicast data message and the retransmission of the multicast data message, wherein transmitting the feedback is based on decoding only one of the multicast data message or the retransmission of the multicast data message.

32. The method of claim 14 , wherein the unicast downlink shared channel is scheduled to be received without overlap of the multicast downlink shared channel, in accordance with a scheduling rule that prohibits overlap of multiple downlink transmissions associated with a same feedback process identifier.

33. The method of claim 14 , wherein transmitting the feedback pertaining to the multicast data message further comprises:

transmitting the feedback via at least one of a first scheduled feedback message corresponding to the multicast data message or a second scheduled feedback message corresponding to the retransmission of the multicast data message, wherein the second scheduled feedback message is scheduled to be transmitted after transmission of the first scheduled feedback message in accordance with a scheduling rule that prohibits transmission of the second scheduled feedback message prior to transmission of the first scheduled feedback message.

34. The method of claim 14 , wherein the retransmission of the multicast data message is scheduled to be received after a last symbol of the multicast data message, in accordance with a scheduling rule that prohibits scheduling the retransmission of the multicast data message to begin prior to the last symbol of the multicast data message when the second downlink control information message is received after the first downlink control information message.

35. The method of claim 14 , wherein

the retransmission of the multicast data message is scheduled to be received at least a threshold number of symbols after a last symbol of a system information message, in accordance with a scheduling rule that prohibits scheduling a retransmission within less than the threshold number of symbols after the last symbol of the system information message, and

the threshold number of symbols is based at least in part on a subcarrier spacing configuration.

36. An apparatus for wireless communications at a user equipment (UE), comprising:

a processor;

memory in communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to:

receive a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a feedback process identifier associated with the multicast data message;

receive a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating the feedback process identifier as being associated with the unicast downlink shared channel; and

transmit feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the feedback process identifier being associated with both the multicast data message and the retransmission of the multicast data message.

37. An apparatus for wireless communications at a base station, comprising:

a processor;

memory in communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to:

transmit, to a user equipment (UE), a first downlink control information message scheduling transmission of a multicast data message in a multicast downlink shared channel, the first downlink control information message also indicating a feedback process identifier associated with the multicast data message;

transmit a second downlink control information message scheduling a unicast downlink shared channel that includes a retransmission of the multicast data message, the second downlink control information message also indicating the feedback process identifier as being associated with the unicast downlink shared channel; and

receive feedback pertaining to the multicast data message based at least in part on at least one of the multicast downlink shared channel or the unicast downlink shared channel and the feedback process identifier being associated with both the multicast data message and the retransmission of the multicast data message.