Method and apparatus for performing MIMO operation on a set of cells based on layer 2 mobility in mobile wireless communication system

1. A wireless device comprising:

a wireless transceiver;

at least one processor; and

a memory storing instructions that, when executed by the at least one processor, cause the wireless device to:

receive, from a base station, at least one Radio Resource Control (RRC) message, wherein the at least one RRC message comprises:

first configuration information indicating a Transmission Configuration Index (TCI) state list of a first cell; and

second configuration information indicating a TCI state list of a second cell;

receive, from the base station and via the second cell, a first Medium Access Control (MAC) Control Element (CE), wherein the first MAC CE comprises an identifier associated with the first configuration information and associated with a first TCI state identifier, and wherein the first TCI state identifier indicates a first TCI state of the TCI state list of the first cell;

monitor, based on the first MAC CE and based on the first TCI state, Physical Downlink Control Channel (PDCCH) associated with the first cell;

receive, from the base station and via the first cell, a second MAC CE, wherein the second MAC CE comprises an identifier associated with the second configuration information and associated with a second TCI state identifier, and wherein the second TCI state identifier indicates a second TCI state of the TCI state list of the second cell; and

monitor, based on the second MAC CE and based on the second TCI state, PDCCH associated with the second cell.

2. The wireless device of claim 1 , wherein the instructions, when executed by the at least one processor, cause the wireless device to, while the first configuration information and the second configuration information are configured for the wireless device,

receive the first MAC CE; and

receive the second MAC CEb.

3. The wireless device of claim 1 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

apply, based on the first MAC CE, at least one parameter of the first configuration information; and

apply, based on the second MAC CE, at least one parameter of the second configuration information.

4. The wireless device of claim 3 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

perform, based on the applied at least one parameter of the first configuration information, wireless communication via the first cell; and

perform, based on the applied at least one parameter of the second configuration information, wireless communication via the second cell.

5. The wireless device of claim 1 , wherein the first cell is associated with a first layer-2 mobility group, and wherein the second cell is associated with a second layer-2 mobility group.

6. The wireless device of claim 5 , wherein the instructions, when executed by the at least one processor, cause the wireless device to, while the first configuration information and the second configuration information are configured for the wireless device,

receive the first MAC CE; and

switch, based on the first MAC CE, from the second layer-2 mobility group to the first layer-2 mobility group.

7. The wireless device of claim 6 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

while the first configuration information and the second configuration information are configured for the wireless device,

receive the second MAC CE; and

switch, based on the second MAC CE, from the first layer-2 mobility group to the second layer-2 mobility group.

8. The wireless device of claim 1 , wherein the instructions, when executed by the at least one processor, cause the wireless device to receive the at least one RRC message by:

receiving, from the base station, a first RRC message, wherein the first RRC message comprises the first configuration information; and

receiving, from the base station, a second RRC message, wherein the second RRC message comprises the second configuration information.

9. A wireless device comprising:

a wireless transceiver;

at least one processor; and

a memory storing instructions that, when executed by the at least one processor, cause the wireless device to:

receive, from a base station, at least one Radio Resource Control (RRC) message, wherein the at least one RRC message comprises:

first configuration information associated with at least one first cell; and

second configuration information associated with at least one second cell; and

while the first configuration information and the second configuration information are configured for the wireless device:

perform, based on the second configuration information, wireless communication via at least one cell of the at least one second cell;

after performing the wireless communication via at least one cell of the at least one second cell, receive a first Medium Access Control (MAC) Control Element (CE), wherein the first MAC CE comprises an identifier associated with the first configuration information and associated with a Transmission Configuration Index (TCI) state list of the at least one first cell; and

based on the first MAC CE, perform, using at least one TCI state of the TCI state list of the at least one first cell, wireless communication via at least one cell of the at least one first cell.

10. The wireless device of claim 9 , wherein:

the first configuration information indicates the TCI state list of the at least one first cell; and

the second configuration information indicates a TCI state list of the at least one second cell.

11. The wireless device of claim 9 , wherein:

the identifier is associated with a first TCI state identifier; and

the first TCI state identifier indicates a first TCI state of the TCI state list of the at least one first cell.

12. The wireless device of claim 9 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

while the first configuration information and the second configuration information are configured for the wireless device, and after performing the wireless communication via at least one cell of the at least one first cell, receive a second MAC CE, wherein the second MAC CE comprises an identifier associated with the second configuration information and associated with a TCI state list of the at least one second cell; and

based on the second MAC CE, perform, using at least one TCI state of the TCI state list of the at least one second cell, wireless communication via at least one cell of the at least one second cell.

13. The wireless device of claim 12 , wherein:

the identifier associated with the second configuration information is associated with a second TCI state identifier; and

the second TCI state identifier indicates a second TCI state of the TCI state list of the at least one second cell.

14. The wireless device of claim 9 , wherein the at least one first cell is associated with a first layer-2 mobility group, and wherein the at least one second cell is associated with a second layer-2 mobility group.

15. The wireless device of claim 14 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

while the first configuration information and the second configuration information are configured for the wireless device, switch, based on the first MAC CE, from the second layer-2 mobility group to the first layer-2 mobility group.

16. The wireless device of claim 15 , wherein the instructions, when executed by the at least one processor, cause the wireless device to:

while the first configuration information and the second configuration information are configured for the wireless device, switch, based on a second MAC CE, from the first layer-2 mobility group to the second layer-2 mobility group, and

wherein the second MAC CE comprises an identifier associated with the second configuration information and associated with a TCI state list of the at least one second cell.

17. The wireless device of claim 9 , wherein the instructions, when executed by the at least one processor, cause the wireless device to receive the at least one RRC message by:

receiving, from the base station, a first RRC message, wherein the first RRC message comprises the first configuration information; and

receiving, from the base station, a second RRC message, wherein the second RRC message comprises the second configuration information.