Receiver feedback about potential collisions

1. A method of wireless communication at a receiving device, comprising:

before identifying a collision between a first set of resources and a second set of resources, receiving a first resource reservation message for scheduling a reservation of the first set of resources for future transmission from a first transmitting device, the first resource reservation message being received on resources different from the first set of resources, and receiving a second resource reservation message for scheduling a reservation of the second set of resources for future transmission from a second transmitting device, the second resource reservation message being received on resources different from the second set of resources;

identifying the collision between the first set of resources reserved by a first transmitting device and the second set of resources reserved by the second transmitting device based on the received first resource reservation message and the received second resource reservation message; and

transmitting a collision indication to one of the first transmitting device or the second transmitting device based on the identified collision.

2. The method of claim 1 , wherein the identification of the collision is based on an overlap between the first set of resources and the second set of resources.

3. The method of claim 2 , wherein the identification of the collision is further based on a difference in a measured reference signal received power (RSRP) for a first signal indicating the first set of resources reserved by the first transmitting device and a second signal indicating the second set of resources reserved by the second transmitting device.

4. The method of claim 2 , wherein the identification of the collision is further based on a distance between the receiving device and the first transmitting device and the second transmitting device or between the first transmitting device and the second transmitting device.

5. The method of claim 1 , further comprising:

receiving the first resource reservation message from the first transmitting device; and

receiving the second resource reservation message from the second transmitting device after receiving the first resource reservation message,

wherein the transmission of the collision indication is to the second transmitting device based on the second resource reservation message being received after the first resource reservation message.

6. The method of claim 1 , further comprising:

determining to transmit the collision indication to the first transmitting device or the second transmitting device based, at least in part, on a first priority of communication associated with the first transmitting device and a second priority of communication associated with the second transmitting device.

7. The method of claim 1 , further comprising:

receiving the first resource reservation message from the first transmitting device within a same slot as receiving the second resource reservation message from the second transmitting device, wherein the first transmitting device and the second transmitting device have a same priority; and

determining to transmit the collision indication to the first transmitting device or the second transmitting device based, at least in part, on a starting resource block for the first set of resources and a starting resource block (RB) for the second set of resources.

8. The method of claim 1 , further comprising:

receiving the first resource reservation message from the first transmitting device within a same slot as receiving the second resource reservation message from the second transmitting device, wherein the first transmitting device and the second transmitting device have a same priority; and

determining to transmit the collision indication to the first transmitting device or the second transmitting device based, at least in part, on an ending resource block for the first set of resources and an ending RB for the second set of resources.

9. The method of claim 1 , further comprising:

receiving the first resource reservation message from the first transmitting device within a same slot as receiving the second resource reservation message from the second transmitting device, wherein the first transmitting device and the second transmitting device have a same priority and a same resource allocation; and

determining to transmit the collision indication to the first transmitting device or the second transmitting device based, at least in part, on first device identifier (ID) for the first transmitting device and second device ID for the second transmitting device.

10. The method of claim 1 , further comprising:

receiving the first resource reservation message from the first transmitting device within a same slot as receiving the second resource reservation message from the second transmitting device, wherein the first transmitting device and the second transmitting device have a same priority, a same resource allocation, and are associated with a same set of bits for a device identifier (ID); and

randomly determining to transmit the collision indication to the first transmitting device or the second transmitting device.

11. The method of claim 1 , wherein the collision indication is transmitted on a resource reserved for the collision indication by the first transmitting device or the second transmitting device.

12. The method of claim 11 , further comprising:

receiving the first resource reservation message from the first transmitting device having an associated first collision indication resource; and

receiving the second resource reservation message from the second transmitting device after receiving the first resource reservation message having a second collision indication resource,

wherein the collision indication is transmitted using the associated first collision indication resource or an associated second collision indication resource.

13. The method of claim 1 , wherein the collision indication is transmitted on a feedback channel.

14. The method of claim 13 , wherein the collision indication comprises a feedback sequence for a non-clear to send (non-CTS) indication.

15. A method of wireless communication at a transmitting device, comprising:

before receiving a collision indication between a first set of resources and a second set of resources from a receiving device of at least one receiving device, transmitting a resource reservation for a transmission from the transmitting device to the at least one receiving device;

receiving the collision indication from the receiving device of the at least one receiving device for a collision between the first set of resources reserved by the resource reservation and the second set of resources reserved by another transmitting device, the collision indication being received on a third set of resources different from the first set of resources and the second set of resources; and

backing off from transmitting on the first set of resources reserved by the resource reservation in response to receiving the collision indication from the receiving device.

16. The method of claim 15 , wherein the collision indication is received on a collision indication resource reserved for the collision indication.

17. The method of claim 16 , wherein the resource reservation includes the collision indication resource.

18. The method of claim 15 , wherein the collision indication is received on a feedback channel.

19. The method of claim 18 , wherein the collision indication comprises a feedback sequence for a non-clear to send (non-CTS) indication.

20. The method of claim 15 , wherein the backing off from transmitting on the first set of resources reserved by the resource reservation comprises:

refraining from transmitting the transmission on the first set of resources reserved by the resource reservation for at least a duration of a backoff timer; and

transmitting another resource reservation for the transmission from the transmitting device to the at least one receiving device after the duration of the backoff timer.

21. An apparatus for wireless communication by a receiving device, comprising:

a memory; and

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

before identifying a collision between a first set of resources and a second set of resources, receive a first resource reservation message for scheduling a reservation of the first set of resources for future transmission from a first transmitting device, the first resource reservation message being received on resources different from the first set of resources, and receive a second resource reservation message for scheduling a reservation of the second set of resources for future transmission from a second transmitting device, the second resource reservation message being received on resources different from the second set of resources;

identify the collision between the first set of resources reserved by the first transmitting device and the second set of resources reserved by the second transmitting device based on the received first resource reservation message and the received second resource reservation message; and

transmit a collision indication to one of the first transmitting device or the second transmitting device based on the identified collision.

22. The apparatus of claim 21 , wherein the identification of the collision is based on an overlap between the first set of resources and the second set of resources.

23. The apparatus of claim 22 , wherein the identification of the collision is further based on a difference in a measured reference signal received power (RSRP) for a first signal indicating the first set of resources reserved by the first transmitting device and a second signal indicating the second set of resources reserved by the second transmitting device.

24. The apparatus of claim 22 , wherein the identification of the collision is further based on a distance between the receiving device and the first transmitting device and the second transmitting device or between the first transmitting device and the second transmitting device.

25. The apparatus of claim 21 , wherein the collision indication is transmitted on a resource reserved for the collision indication by the first transmitting device or the second transmitting device.

26. The apparatus of claim 21 , wherein the collision indication is transmitted on a feedback channel, and the collision indication comprises a feedback sequence for a non-clear to send (non-CTS) indication.

27. An apparatus for wireless communication by a transmitting device, comprising:

a memory; and

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

before receiving a collision indication between a first set of resources and a second set of resources from a receiving device of at least one receiving device, transmit a resource reservation for a transmission from the transmitting device to the at least one receiving device;

receive the collision indication from the receiving device of the at least one receiving device for a collision between the first set of resources reserved by the resource reservation and the second set of resources reserved by another transmitting device, the collision indication being received on a third set of resources different from the first set of resources and the second set of resources; and

back off from transmitting on the first set of resources reserved by the resource reservation in response to receiving the collision indication from the receiving device.

28. The apparatus of claim 27 , wherein the collision indication is received on a collision indication resource reserved for the collision indication.

29. The apparatus of claim 28 , wherein the resource reservation includes the collision indication resource.

30. The apparatus of claim 27 , wherein the collision indication is received on a feedback channel.

31. The apparatus of claim 21 , wherein the collision indication is transmitted to the first transmitting device or the second transmitting device based, at least in part, on a first priority of communication associated with the first transmitting device and a second priority of communication associated with the second transmitting device.

32. The apparatus of claim 21 , wherein the collision indication is transmitted on a resource reserved for the collision indication by the first transmitting device or the second transmitting device.

33. The apparatus of claim 21 , wherein the collision indication is transmitted on a feedback channel.

34. The method of claim 1 , wherein the receiving device, the first transmitting device, and the second transmitting device each comprise a user equipment (UE), and wherein the collision indication is transmitted in a sidelink communication.

35. The method of claim 15 , wherein the transmitting device, the receiving device, and the another transmitting device each comprise a user equipment (UE), and wherein the collision indication is transmitted in a sidelink communication.

36. The apparatus of claim 21 , wherein the receiving device, the first transmitting device, and the second transmitting device each comprise a user equipment (UE), and wherein the collision indication is transmitted in a sidelink communication.

37. The apparatus of claim 27 , wherein the transmitting device, the receiving device, and the another transmitting device each comprise a user equipment (UE), and wherein the collision indication is transmitted in a sidelink communication.