Timing advance update for non-serving cell

1. A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory the one or more processors configured to cause the UE to:

receive or determine, based at least in part on a timing advance group identifier of a non-serving cell, information indicating a timing advance for the non-serving cell of the UE; and

perform an inter-cell mobility operation based at least in part on the timing advance for the non-serving cell of the UE.

2. The UE of claim 1 , wherein the inter-cell mobility operation is a Layer 1 or Layer 2-based inter-cell mobility operation.

3. The UE of claim 1 , wherein the non-serving cell is a neighbor cell of the UE.

4. The UE of claim 1 , wherein the non-serving cell is identified by a physical cell identifier of the non-serving cell.

5. The UE of claim 1 , wherein the timing advance is associated with a timing advance group to which the non-serving cell belongs.

6. The UE of claim 5 , wherein the one or more processors are further configured to cause the UE to:

receive signaling indicating that the non-serving cell belongs to the timing advance group.

7. The UE of claim 1 , wherein the information indicating the timing advance indicates a physical cell identifier of the non-serving cell or the timing advance group identifier for a timing advance group to which the non-serving cell belongs.

8. The UE of claim 7 , wherein the timing advance group identifier is signaled using at least one of: radio resource control signaling, a medium access control control element, or downlink control information.

9. The UE of claim 7 , wherein the timing advance is for all cells of the timing advance group.

10. The UE of claim 1 , wherein the timing advance is based at least in part on a random access channel (RACH) preamble transmitted to the non-serving cell by the UE.

11. The UE of claim 10 , wherein the RACH preamble is triggered by a physical downlink control channel order received from a serving cell of the UE or from the non-serving cell.

12. The UE of claim 10 , wherein the information indicating the timing advance is received in a RACH response.

13. The UE of claim 1 , wherein the timing advance is based at least in part on a sounding reference signal (SRS) transmitted by the UE to at least one of a serving cell or the non-serving cell.

14. The UE of claim 13 , wherein the SRS is scheduled by the serving cell.

15. The UE of claim 13 , wherein the SRS is triggered by downlink control information.

16. The UE of claim 1 , wherein the one or more processors are further configured to cause the UE to:

receive, from the non-serving cell and a serving cell, respective signals, wherein determining the information indicating the timing advance is based at least in part on measuring a reception timing difference between the respective signals.

17. The UE of claim 16 , wherein the one or more processors are further configured to cause the UE to:

transmit information indicating the reception timing difference to at least one of the serving cell or the non-serving cell.

18. The UE of claim 16 , wherein the respective signals comprise synchronization signal blocks.

19. A base station for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, the one or more processors configured to:

determine, based at least in part on a timing advance group identifier of a non-serving cell, information indicating a timing advance for the non-serving cell of a user equipment (UE); and

transmit the information indicating the timing advance to the UE.

20. The base station of claim 19 , wherein the one or more processors are further configured to cause the UE to:

perform a Layer 1 or Layer 2-based inter-cell mobility operation based at least in part on the timing advance for the non-serving cell of the UE.

21. The base station of claim 19 , wherein the non-serving cell is a neighbor cell of the UE.

22. The base station of claim 19 , wherein the non-serving cell is identified by a physical cell identifier of the non-serving cell.

23. The base station of claim 19 , wherein the timing advance is associated with a timing advance group to which the non-serving cell belongs.

24. The base station of claim 23 , wherein the one or more processors are further configured to cause the UE to:

transmit signaling indicating that the non-serving cell belongs to the timing advance group.

25. The base station of claim 19 , wherein the information indicating the timing advance indicates a physical cell identifier of the non-serving cell or the timing advance group identifier for a timing advance group to which the non-serving cell belongs.

26. The base station of claim 19 , wherein the timing advance is based at least in part on a random access channel (RACH) preamble transmitted to the non-serving cell by the UE.

27. The base station of claim 19 , wherein the timing advance is based at least in part on receiving a sounding reference signal (SRS) from the UE.

28. The base station of claim 27 , wherein the one or more processors are further configured to cause the UE to:

schedule the SRS to be transmitted to the serving cell or the non-serving cell.

29. A method of wireless communication performed by a user equipment (UE), comprising:

receiving or determining, based at least in part on a timing advance group identifier of a non-serving cell, information indicating a timing advance for the non-serving cell of the UE; and

performing an inter-cell mobility operation based at least in part on the timing advance for the non-serving cell of the UE.

30. A method of wireless communication performed by a base station, comprising:

determining, based at least in part on a timing advance group identifier of a non-serving cell, information indicating a timing advance for the non-serving cell of a user equipment (UE); and

transmitting the information indicating the timing advance to the UE.