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

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.