Method for managing tracking area identity list and user equipment using the same and communication system using the same

1. A method for managing a tracking area identity (TAI) list to be used by a user equipment (UE), and the method comprising:

storing, by the UE, a forbidden TAI list;

receiving, by the UE, a first message comprising a TAI list from a mobile management entity (MME), wherein the first message is one of ATTACH ACCEPT or GUTI REALLOCATION COMMAND;

determining, by the UE, whether the received TAI list and the forbidden TAI list contain a first tracking area which is on both the received TAI list and the forbidden tracking area list;

in response to obtaining the first tracking area through comparing the TAI list received from the first message and the forbidden TAI list stored in the UE, revising, by the UE, the received TAI list by removing the first tracking area from the received TAI list such that the first tracking area is only on the forbidden TAI list;

updating, by the UE, a previous TAI list stored in the UE by using the revised TAI list not including the first tracking area; and

synchronizing, by the UE, the revised TAI list with the MME of a serving network.

2. The method of claim 1 , wherein updating the previous TAI list further comprises:

removing all tracking areas which are on both the TAI list and the forbidden list from the previous TAI list.

3. The method of claim 1 , wherein determining whether the TAI list and the forbidden TAI list contain the first tracking area which is on both the TAI list and the forbidden tracking area list comprises:

determining whether the TAI list and the forbidden TAI list contain overlapping tracking areas during a tracking area update (TAU) event.

4. The method of claim 1 further comprising: updating the forbidden TAI list and synchronizing the forbidden TAI list with a serving network.

5. A user equipment comprising:

a storage medium for storing a forbidden TAI list;

a transceiver for receiving a first message comprising a TAI list from a mobile management entity (MME), wherein the first message is one of ATTACH ACCEPT or GUTI REALLOCATION COMMAND; and

a processor coupled to the storage and the transceiver and configured for determining whether the received TAI list and the forbidden TAI list contain a first tracking area which is on both the received TAI list and the forbidden tracking area list, in response to obtaining the first tracking area through comparing the TAI list received from the first message and the forbidden TAI list stored in the user equipment, revising the received TAI list by removing the first tracking area from the received TAI list such that the first tracking area is only on the forbidden TAI list, and updating a previous TAI list stored in the UE by using the revised TAI list not including the first tracking area, and synchronizing the revised TAI list with the MME of a serving network.

6. The user equipment of claim 5 , wherein the processor is configured for updating the previous TAI list further comprises removing all tracking areas which are on both the TAI list and the forbidden list from the previous TAI list.

7. The user equipment of claim 5 , wherein the processor is configured for determining whether the TAI list and the forbidden TAI list contain the first tracking area which is on both the TAI list and the forbidden TAI list comprises determining whether the TAI list and the forbidden TAI list contain overlapping tracking areas during a tracking area update (TAU) event.

8. The user equipment of claim 5 , wherein the processor is further configured for comprising: updating the forbidden TAI list and synchronizing the forbidden TAI list with a serving network.

9. A communication system comprising a network control node and a user equipment (UE) which stores a forbidden TAI list, wherein the network control node is configured for transmitting a first message comprising a TAI list, wherein the first message is one of ATTACH ACCEPT or GUTI REALLOCATION COMMAND; and the UE is configured for determining from the first message whether the received TAI list and the forbidden TAI list contain a first tracking area which is on both the received TAI list and the forbidden tracking area list, in response to obtaining the first tracking area through comparing the TAI list received from the first message and the forbidden TAI list stored in the UE, revising the received TAI list by removing the first tracking area from the received TAI list such that the first tracking area is only on the forbidden TAI list, and updating a previous TAI list stored in the UE by using the revised TAI list not including the first tracking area, and synchronizing the revised TAI list with the network control node of a serving network.

10. The communication system of claim 9 , wherein the UE updating the previous TAI list comprising removing all tracking areas which are on both the TAI list and the forbidden list from the previous TAI list.

11. The communication system of claim 9 , wherein the UE determining whether the TAI list and the forbidden TAI list contain the first tracking area which is on both the TAI list and the forbidden tracking area list comprises:

determining whether the TAI list and the forbidden TAI list contain overlapping tracking areas during a tracking area update (TAU) event.