Dynamic configuration of physical sidelink feedback channel format

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

determining that the first UE is to receive a sidelink transmission from a second UE, the sidelink transmission comprising a sidelink control channel and a sidelink data channel;

receiving, based at least in part on a first resource configuration for a sidelink feedback channel failing to satisfy a resource threshold associated with transmitting a feedback message, an indication of a second resource configuration from the second UE, the second resource configuration for transmitting the feedback message to the second UE for the sidelink transmission, the second resource configuration satisfying the resource threshold;

receiving the sidelink transmission from the second UE; and

transmitting, to the second UE, the feedback message using the second resource configuration.

2. The method of claim 1 , wherein the first resource configuration is configured during a first slot, further comprising:

selecting, based at least in part on the first resource configuration failing to satisfy the resource threshold, a second slot to transmit the feedback message, the second slot being a different slot than the first slot.

3. The method of claim 1 , wherein the first resource configuration is configured during two symbols of a slot, further comprising:

selecting, based at least in part on the first resource configuration failing to satisfy the resource threshold, a set of additional symbols of the slot for the second resource configuration, the set of additional symbols being different symbols than the two symbols allocated to the first resource configuration.

4. The method of claim 3 , further comprising:

transmitting the feedback message over the set of additional symbols or multiplexed over the set of additional symbols and the two symbols.

5. The method of claim 1 , wherein receiving the indication comprises:

receiving a scaler that allocates a first set of symbols to the sidelink data channel and a second set of symbols to the sidelink feedback channel for the feedback message.

6. The method of claim 1 , further comprising:

transmitting sidelink control signaling using the second resource configuration, the sidelink control signaling being different from the feedback message.

7. The method of claim 1 , wherein the second resource configuration is for a slot of the sidelink data channel.

8. The method of claim 7 , further comprising:

transmitting the feedback message during a last two symbols of the slot for the sidelink data channel using a hybrid automatic repeat/request acknowledgement (HARQ-ACK) format message associated with a physical uplink control channel.

9. The method of claim 7 , further comprising:

multiplexing the feedback message with sidelink data to obtain a multiplexed message; and

transmitting the multiplexed message during the slot of the sidelink data channel.

10. The method of claim 7 , further comprising:

transmitting the feedback message, sidelink control signaling, or both, in a sidelink control information two format message via the sidelink data channel.

11. The method of claim 1 , wherein the second resource configuration is for a slot comprising the sidelink feedback channel.

12. The method of claim 11 , further comprising:

identifying, based at least in part on the first resource configuration, a last two symbols of the slot comprising the sidelink feedback channel; and

selecting an additional set of symbols of the slot for the second resource configuration.

13. The method of claim 11 , further comprising:

identifying, based at least in part on the first resource configuration, a last three symbols of the slot comprising the sidelink feedback channel and a gap period occurring prior to the sidelink feedback channel; and

receiving, based at least in part on the second resource configuration, the sidelink transmission via the sidelink data channel during one or more symbols of the last three symbols of the slot.

14. The method of claim 11 , further comprising:

identifying, based at least in part on the first resource configuration, a last three symbols of the slot comprising the sidelink feedback channel and a gap period occurring prior to the sidelink feedback channel; and

transmitting, based at least in part on the second resource configuration, the feedback message via the sidelink feedback channel during one or more symbols of the last three symbols of the slot.

15. A method for wireless communication at a first user equipment (UE), comprising:

determining that the first UE is to transmit a sidelink transmission to a second UE, the sidelink transmission comprising a sidelink control channel and a sidelink data channel;

transmitting, based at least in part on a first resource configuration for a sidelink feedback channel failing to satisfy a resource threshold associated with receiving a feedback message, an indication of a second resource configuration to the second UE for receiving the feedback message from the second UE for the sidelink transmission, the second resource configuration satisfying the resource threshold;

transmitting the sidelink transmission to the second UE; and

receiving, from the second UE, a feedback message using the second resource configuration.

16. The method of claim 15 , wherein the first resource configuration is configured during a first slot, further comprising:

selecting, based at least in part on the first resource configuration failing to satisfy the resource threshold, a second slot to transmit the feedback message, the second slot being a different slot than the first slot.

17. The method of claim 15 , wherein the first resource configuration is configured during two symbols of a slot, further comprising:

selecting, based at least in part on the first resource configuration failing to satisfy the resource threshold, a set of additional symbols of the slot for the second resource configuration, the set of additional symbols being different symbols than the two symbols allocated to the first resource configuration.

18. The method of claim 17 , further comprising:

transmitting the feedback message over the set of additional symbols or multiplexed over the set of additional symbols and the two symbols.

19. The method of claim 15 , wherein transmitting the indication comprises:

transmitting a scaler that allocates a first set of symbols to the sidelink data channel and a second set of symbols to the sidelink feedback channel for the feedback message.

20. The method of claim 15 , further comprising:

receiving sidelink control signaling using the second resource configuration, the sidelink control signaling being different from the feedback message.

21. The method of claim 15 , wherein the second resource configuration is for a slot of the sidelink data channel.

22. The method of claim 21 , further comprising:

receiving the feedback message during a last two symbols of the slot for the sidelink data channel using a hybrid automatic repeat/request acknowledgement (HARQ-ACK) format message associated with a physical uplink control channel.

23. The method of claim 21 , further comprising:

receiving a multiplexed message during the slot of the sidelink data channel, the multiplexed message obtained by the second UE multiplexing the feedback message with sidelink data.

24. The method of claim 21 , further comprising:

receiving the feedback message, sidelink control signaling, or both, in a sidelink control information two format message via the sidelink data channel.

25. The method of claim 15 , wherein the second resource configuration is for a slot comprising the sidelink feedback channel.

26. The method of claim 25 , further comprising:

identifying, based at least in part on the first resource configuration, a last two symbols of the slot comprising the sidelink feedback channel; and

selecting an additional set of symbols of the slot for the second resource configuration.

27. The method of claim 25 , further comprising:

identifying, based at least in part on the first resource configuration, a last three symbols of the slot comprising the sidelink feedback channel and a gap period occurring prior to the sidelink feedback channel; and

transmitting, based at least in part on the second resource configuration, the sidelink transmission via the sidelink data channel during one or more symbols of the last three symbols of the slot.

28. The method of claim 25 , further comprising:

identifying, based at least in part on the first resource configuration, a last three symbols of the slot comprising the sidelink feedback channel and a gap period occurring prior to the sidelink feedback channel; and

receiving, based at least in part on the second resource configuration, the feedback message via the sidelink feedback channel during one or more symbols of the last three symbols of the slot.

29. An apparatus for wireless communication at a first user equipment (UE), comprising:

a processor;

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

determine that the first UE is to receive a sidelink transmission from a second UE, the sidelink transmission comprising a sidelink control channel and a sidelink data channel;

receive, based at least in part on a first resource configuration for a sidelink feedback channel failing to satisfy a resource threshold associated with transmitting a feedback message, an indication of a second resource configuration from the second UE, the second resource configuration for transmitting the feedback message to the second UE for the sidelink transmission, the second resource configuration satisfying the resource threshold;

receive the sidelink transmission from the second UE; and

transmit, to the second UE, the feedback message using the second resource configuration.

30. An apparatus for wireless communication at a first user equipment (UE), comprising:

a processor;

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

determine that the first UE is to transmit a sidelink transmission to a second UE, the sidelink transmission comprising a sidelink control channel and a sidelink data channel;

transmit, based at least in part on a first resource configuration for a sidelink feedback channel failing to satisfy a resource threshold associated with receiving a feedback message, an indication of a second resource configuration to the second UE for receiving the feedback message from the second UE for the sidelink transmission, the second resource configuration satisfying the resource threshold;

transmit the sidelink transmission to the second UE; and

receive, from the second UE, a feedback message using the second resource configuration.