Enhanced Mechanism of Uplink Time Alignment Maintenance for Inter-eNB Carrier Aggregation

A user equipment (UE), comprising:

• a transceiver that transmits and receives radio signals;
• a memory;
• and
• a processor coupled to the memory, the processor configured to detect an inter-eNB CA and assigns serving cells with uplink group identifiers, wherein the serving cells are served by a first or a second base station in a wireless network;
• retrieve a first cell group with a first cell group identifier containing one or more serving cells with the same or different uplink group identifiers served by the first base station and a second cell group with a second cell group identifier containing one or more serving cells with the same or different uplink group identifiers served by the second base station, and wherein the uplink group identifier is associated with a cell time advancing group (TAG) and the cell group identifier is associated with a group TAG, and wherein each cell TAG associates with the same base station belongs to the same group TAG, and wherein each cell TAG has a time advance timer (TAT);
• and perform uplink alignment, monitoring and management procedures linking to the first or the second cell group identifier.