Method and apparatus for handling feedback resource for groupcast in sidelink in a wireless communication system
A method and apparatus are disclosed from the perspective of a first device to determine sidelink feedback resource associated with sidelink communication. In one embodiment, the method includes the first device receiving an identifier from an upper layer of the first device. The method also includes the first device receiving a sidelink transmission from a second device. The method further includes the first device determining a sidelink feedback resource associated with the sidelink transmission at least based on the identifier and a source ID (Identity) associated with the sidelink transmission. In addition, the method includes the first device using the sidelink feedback resource to transmit a feedback in response to the sidelink transmission to the second device.
1. A method for a first device to determine sidelink feedback resource associated with sidelink communication, comprising:
receiving an identifier from an upper layer of the first device;
receiving a sidelink transmission from a second device;
determining a sidelink feedback resource associated with the sidelink transmission at least based on the identifier and a source Identity (ID) associated with the sidelink transmission and further based on a remainder of the identifier divided by a total number of sidelink feedback resources associated with the sidelink transmission; and
using the sidelink feedback resource to transmit a feedback in response to the sidelink transmission to the second device.
2. The method of claim 1 , wherein the sidelink feedback resource is associated with an index.
3. The method of claim 1 , wherein the upper layer is Vehicle-to-Everything (V2X) application layer of the first device or V2X layer of the first device.
4. The method of claim 1 , wherein the identifier is member ID of the first device associated with a group.
5. The method of claim 4 , wherein the first device performs the sidelink communication for the group.
6. The method of claim 4 , wherein each device in the group is associated with a member ID different from member IDs associated with other devices in the group.
7. The method of claim 1 , wherein the source ID is a part of layer-2 source ID of the second device.
8. The method of claim 1 , wherein the sidelink transmission is groupcast transmission.
9. The method of claim 1 , wherein the first device transmits the feedback as Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK) on the sidelink feedback resource if the first device successfully decodes the sidelink transmission.
10. The method of claim 1 , wherein the first device transmits the feedback as Hybrid Automatic Repeat Request-Negative Acknowledgement (HARQ-NACK) on the sidelink feedback resource if the first device does not successfully decode the sidelink transmission.
11. A method for a second device to receive sidelink feedback associated with sidelink communication, comprising:
transmitting a sidelink transmission to at least a first device in a group; and
receiving, on a sidelink feedback resource, a feedback associated with the sidelink transmission from the first device, wherein the sidelink feedback resource is determined at least based on an identifier of the first device and a source Identity (ID) associated with the sidelink transmission and further based on a remainder of the identifier divided by a total number of sidelink feedback resources associated with the sidelink transmission.
12. The method of claim 11 , wherein the sidelink feedback resource is associated with an index.
13. The method of claim 11 , wherein the identifier of the first device is received from an upper layer of the first device, and/or the upper layer is Vehicle-to-Everything (V2X) application layer of the first device or V2X layer of the first device.
14. The method of claim 11 , wherein the identifier is member ID of the first device associated with the group.
15. The method of claim 14 , wherein each device in the group is associated with a member ID different from member IDs associated with other devices in the group.
16. The method of claim 11 , further comprising:
the second device transmits the sidelink transmission to a plurality of devices in a group; and
the second device receives, on a plurality of sidelink feedback resources, a plurality of feedbacks associated with the sidelink transmission from the plurality of devices in the group,
wherein each of the plurality of sidelink feedback resources is determined at least based on an identifier of one corresponding device among the plurality of devices and the source ID associated with the sidelink transmission.
17. The method of claim 16 , wherein the identifier of the one corresponding device is member ID of the one corresponding device associated with the group.
18. The method of claim 11 , wherein the source ID is a part of layer-2 source ID of the second device.
19. The method of claim 11 , wherein the sidelink transmission is groupcast transmission.
20. The method of claim 11 , wherein if the sidelink transmission receives the feedback as Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK) on the sidelink feedback resource, the second device considers the sidelink transmission successfully decoded by the first device, and/or
if the second devices receives the feedback as Hybrid Automatic Repeat Request-Negative Acknowledgement (HARQ-NACK) on the sidelink feedback resource, the second device considers the sidelink transmission not successfully decoded by the first device.