Cell synchronization and timing management in a wireless network

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

one or more memories; and

one or more processors coupled to the one or more memories, the one or more processors being configured to:

communicate with a network entity using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

update timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activate, using L1-L2 signaling, a first cell of the plurality of cells; and

update, using L1-L2 signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

2. The UE of claim 1 , wherein a set of cells of the plurality of cells in a same TAG of the one or more TAGS are configured to use a same timing advance (TA) value.

3. The UE of claim 1 , wherein the one or more TAGs comprise a first TAG and a second TAG that is different from the first TAG in terms of configured timing advance (TA) values of the respective cells included in the first TAG and the second TAG.

4. The UE of claim 1 , wherein each of the plurality of cells is assigned to a corresponding TAG of the one or more TAGS, based on at least one of frequency band, repeater usage, cell location, or UE location.

5. The UE of claim 1 , wherein, the one or more TAGS comprise a first TAG and a second TAG, the one or more processors are further configured to:

perform a first random access channel procedure with the PCell to obtain initial uplink (UL) timing for a first set of cells included in the first TAG that comprises the PCell; and

perform a second random access channel procedure with the SCell to obtain initial UL timing for a second set of cells included in the second TAG that comprises exclusively one or more SCells.

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

receive, from the network entity using L1-L2 centric signaling, a command to activate a first cell of the plurality of cells; and

determine a timing advance (TA) value of the first cell based on whether the first cell is assigned to a timing adjustment group (TAG) including at least one activated second cell among the plurality of cells.

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

set the TA value of the first cell the same as a TA value of the at least one activated second cell in response to the first cell and the at least one activated second cell being included in the same TAG.

8. The UE of claim 6 , wherein the command comprises a TA value of the first cell in response to the first cell being associated with a TAG including no activated cell.

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

receive a physical downlink control channel (PDCCH) order to initiate a random access channel procedure with the first cell to obtain the TA value.

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

receive, from the network entity using L1-L2 centric signaling, a TAG update that updates the association between the plurality of cells and the one or more TAGS.

11. A method of wireless communication at a user equipment (UE), comprising:

communicating with a network entity using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

updating timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activating, using L1-L2 signaling, a first cell of the plurality of cells; and

updating, using L1-L2 signaling, a designation of a TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

12. The method of claim 11 , wherein a set of cells of the plurality of cells in a same TAG of the one or more TAGS are configured to use a same timing advance (TA) value.

13. The method of claim 11 , wherein the one or more TAGs comprise a first TAG and a second TAG that is different from the first TAG in terms of configured timing advance (TA) values of the respective cells included in the first TAG and the second TAG.

14. The method of claim 11 , wherein each of the plurality of cells is assigned to a corresponding TAG of the one or more TAGS, based on at least one of frequency band, repeater usage, cell location, or UE location.

15. The method of claim 11 , wherein, the one or more TAGs comprise a first TAG and a second TAG, the method further comprising:

performing a first random access channel procedure with the PCell to obtain initial uplink (UL) timing for a first set of cells included in the first TAG that comprises the PCell; and

performing a second random access channel procedure with the SCell to obtain initial UL timing for a second set of cells included in the second TAG that comprises exclusively one or more SCells.

16. The method of claim 11 , further comprising:

receiving, from the network entity using L1-L2 centric signaling, a command to activate a first cell of the plurality of cells; and

determining a timing advance (TA) value of the first cell based on whether the first cell is assigned to a timing adjustment group (TAG) including at least one activated second cell among the plurality of cells.

17. The method of claim 16 , further comprising:

setting the TA value of the first cell the same as a TA value of the at least one activated second cell in response to the first cell and the at least one activated second cell being included in the same TAG.

18. The method of claim 16 , wherein the command comprises a TA value of the first cell in response to the first cell being associated with a TAG including no activated cell.

19. The method of claim 16 , further comprising:

receiving a physical downlink control channel (PDCCH) order to initiate a random access channel procedure with the first cell to obtain the TA value.

20. The method of claim 11 , further comprising:

receiving, from the network entity using L1-L2 centric signaling, a TAG update that updates the association between the plurality of cells and the one or more TAGS.

21. A network entity for wireless communication, comprising:

one or more memories; and

one or more processors coupled to the one or more memories, the one or more processors being configured to:

communicate with a user equipment (UE) using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

update timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activate, using L1-L2 signaling, a first cell of the plurality of cells; and

update, using L1-L2 signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

22. The network entity of claim 21 , wherein a set of cells of the plurality of cells in a same TAG of the one or more TAGs are configured to use a same timing advance (TA) value.

23. The network entity of claim 21 , wherein the one or more TAGS comprise a first TAG and a second TAG that is different from the first TAG in terms of configured timing advance (TA) values of the respective cells included in the first TAG and the second TAG.

24. The network entity of claim 21 , wherein each of the plurality of cells is assigned to a corresponding TAG of the one or more TAGS, based on at least one of frequency band, repeater usage, cell location, or UE location.

25. The network entity of claim 21 , wherein, the one or more TAGs comprise a first TAG and a second TAG, the one or more processors are further configured to:

perform a first random access channel procedure with the PCell to obtain initial uplink (UL) timing for a first set of cells included in the first TAG that comprises the PCell; and

perform a second random access channel procedure with the SCell to obtain initial UL timing for a second set of cells included in the second TAG that comprises exclusively one or more SCells.

26. The network entity of claim 21 , wherein the one or more processors are further configured to:

transmit, to the UE using L1-L2 centric signaling, a timing advance (TA) value assigned to the TAG including the first cell.

27. The network entity of claim 26 , wherein the TA value of the first cell is the same as a TA value of at least one activated cell in response to the first cell and the at least one activated cell being included in the same TAG.

28. The network entity of claim 26 , wherein the one or more processors are further configured to:

transmit, to the UE, a physical downlink control channel (PDCCH) order to initiate a random access channel procedure with the first cell to obtain the TA value.

29. The network entity of claim 21 , wherein the one or more processors are further configured to:

transmit, to the UE using L1-L2 centric signaling, a TAG update that updates the association between the plurality of cells and the one or more TAGS.

30. A method of wireless communication at a network entity, comprising:

communicating with a user equipment (UE) using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

updating timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activating, using L1-L2 signaling, a first cell of the plurality of cells; and

updating, using L1-L2 signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

31. The method of claim 30 , wherein a set of cells of the plurality of cells in a same TAG of the one or more TAGS are configured to use a same timing advance (TA) value.

32. The method of claim 30 , wherein the one or more TAGS comprise a first TAG and a second TAG that is different from the first TAG in terms of configured timing advance (TA) values of the respective cells included in the first TAG and the second TAG.

33. The method of claim 30 , wherein each of the plurality of cells is assigned to a corresponding TAG of the one or more TAGS, based on at least one of frequency band, repeater usage, cell location, or UE location.

34. The method of claim 30 , wherein the one or more TAGS comprise a first TAG and a second TAG, further comprising:

performing a first random access channel procedure with the PCell to obtain initial uplink (UL) timing for a first set of cells included in the first TAG that comprises the PCell; and

performing a second random access channel procedure with the SCell to obtain initial UL timing for a second set of cells included in the second TAG that comprises exclusively one or more SCells.

35. The method of claim 30 , further comprising:

transmitting, to the UE using L1-L2 centric signaling, a timing advance (TA) value assigned to the TAG including the first cell.

36. The method of claim 35 , wherein the TA value of the first cell is the same as a TA value of at least one activated cell in response to the first cell and the at least one activated cell being included in the same TAG.

37. The method of claim 35 , further comprising:

transmitting, to the UE, a physical downlink control channel (PDCCH) order to initiate a RACH procedure with the first cell to obtain the TA value.

38. The method of claim 30 , further comprising:

transmitting, to the UE using L1-L2 centric signaling, a TAG update that updates the association between the plurality of cells and the one or more TAGS.

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

means for communicating with a network entity using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

means for updating timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

means for activate, using L1-L2 signaling, a first cell of the plurality of cells; and

means for update, using L1-L2 signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

40. A non-transitory computer-readable storage medium comprising code executable by an apparatus for wireless communication, the code causing the apparatus to:

communicate with a network entity using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

update timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activate, using L1-L2 centric signaling, a first cell of the plurality of cells; and

update, using L1-L2 centric signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

41. A network entity for wireless communication, comprising:

means for communicating with a user equipment (UE) using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

means for updating timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

means for activate, using L1-L2 centric signaling, a first cell of the plurality of cells; and

means for update, using L1-L2 centric signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).

42. A non-transitory computer-readable storage medium comprising code executable by an apparatus for wireless communication, the code causing the apparatus to:

communicate with a user equipment (UE) using one or more cells of a plurality of cells that are configured for mobility operations,

the plurality of cells grouped into one or more timing adjustment groups (TAGs);

update timing advance of the plurality of cells per group according to the one or more TAGs in response to the mobility operations;

activate, using L1-L2 centric signaling, a first cell of the plurality of cells; and

update, using L1-L2 centric signaling, a designation of a timing adjustment group (TAG) of the one or more TAGS, the TAG including the first cell based on whether the first cell is a primary serving cell (PCell) or a secondary serving cell (SCell).