Method and apparatus of operating multiple time alignment timers in mobile communication system supporting carrier aggregation

1. A method performed by a terminal supporting carrier aggregation in a wireless communication system, the method comprising:

receiving, from a base station, first timing advance (TA) information associated with a primary timing advance group (PTAG) which is a group of serving cells using same timing advance value for an uplink transmission and includes a primary cell;

starting or restarting a first timing alignment timer (TAT) associated with the PTAG based on the first TA information;

receiving, from the base station, second TA information associated with a secondary timing advance group (STAG) which is a group of serving cells using same timing advance value and does not include the primary cell;

starting or restarting a second TAT associated with the STAG based on the second TA information;

receiving downlink data on at least one serving cell in the STAG;

identifying that a TAT is expired;

in case that the expired TAT is the second TAT associated with the STAG, notifying a radio resource control (RRC) layer to release at least one physical uplink control channel (PUCCH) for serving cells belonging to the STAG;

in case that the expired TAT is the first TAT associated with the PTAG, notifying the RRC layer to release at least one PUCCH for all serving cells belonging to the PTAG and the STAG;

identifying whether the expired TAT is associated with a TAG which includes a serving cell on which hybrid automatic repeat request (HARQ) feedback is to be transmitted and supporting a PUCCH transmission;

in case that the expired TAT is associated with the TAG including the serving cell, an instruction to generate HARQ positive or negative acknowledgement information for the downlink data is not delivered to a physical layer of the terminal; and

in case that the expired TAT is not associated with the TAG including the serving cell, an instruction to generate the HARQ positive or negative acknowledgement information for the downlink data is delivered to the physical layer.

2. The method of claim 1 , further comprising:

suspending uplink data transmission, in case that the expired TAT is the first TAT associated with the PTAG.

3. The method of claim 1 , further comprising:

flushing all HARQ buffers for all serving cells in the PTAG and the STAG, in case that the expired TAT is the first TAT associated with the PTAG.

4. The method of claim 1 , further comprising:

notifying the RRC layer to release a sounding reference signal (SRS) for the serving cells belonging to the STAG, in case that the expired TAT is the second TAT associated with the STAG; and

notifying the RRC layer to release an SRS for all serving cells belonging to the PTAG and the STAG in case that the expired TAT is the first TAT associated with the PTAG.

5. The method of claim 4 , wherein the notifying the RRC layer to release the at least one PUCCH for the serving cells belonging to the STAG and the SRS for the serving cells belonging to the STAG further comprises delivering an identifier (ID) of the STAG.

6. The method of claim 1 , further comprising:

transmitting the HARQ positive or negative acknowledgement information for the downlink data, to the base station through the primary cell, in case that the expired TAT is not associated with the TAG including the serving cell.

7. The method of claim 1 , wherein the first TA information and the second TA information is received in timing advance command media access control (MAC) control element or in a random access response message.

8. A terminal supporting carrier aggregation in a wireless communication system, the terminal comprising:

a transceiver; and

a controller configured to:

receive, from abase station via the transceiver, first timing advance (TA) information associated with a primary timing advance group (PTAG) which is a group of serving cells using same timing advance value for an uplink transmission and includes a primary cell,

start or restart a first TAT associated with the PTAG,

receive, from the base station via the transceiver, second TA information associated with a secondary timing advance group (STAG) which is a group of serving cells using same timing advance value and does not include the primary cell,

start or restart a second TAT associated with the STAG based on the second TA information,

receive, via the transceiver, downlink data on at least one serving cell in the STAG,

identify that a TAT is expired,

in case that the expired TAT is the second TAT associated with the STAG,

in case that the expired TAT is the first TAT associated with the PTAG, notify the RRC layer to release at least one PUCCH for all serving cells belonging to the PTAG and the STAG,

identify whether the expired TAT is associated with a TAG which includes a serving cell on which hybrid automatic repeat request (HARQ) feedback is to be transmitted and supporting a PUCCH transmission,

in case that the expired TAT is associated with the TAG including the serving cell, an instruction to generate HARQ positive or negative acknowledgement information for the downlink data is not delivered to a physical layer of the terminal, and

in case that the expired TAT is not associated with the TAG including the serving cell, an instruction to generate the HARQ positive or negative acknowledgement information for the downlink data is delivered to the physical layer.

9. The terminal of claim 8 , wherein the controller is further configured to suspend uplink data transmission, in case that the expired TAT is the first TAT associated with the PTAG.

10. The terminal of claim 8 , wherein the controller is further configured to:

flush all HARQ buffers for all serving cells in the PTAG and the STAG, in case that the expired TAT is the first TAT associated with the PTAG.

11. The terminal of claim 8 , wherein the controller is further configured to:

notify the RRC layer to release a sounding reference signal (SRS) for the serving cells belonging to the STAG, in case that the expired TAT is the second TAT associated with the STAG, and

notify the RRC layer to release an SRS for all serving cells belonging to the PTAG and the STAG in case that the expired TAT is the first TAT associated with the PTAG.

12. The terminal of claim 11 , wherein the controller is further configured to deliver an identifier (ID) of the STAG.

13. The terminal of claim 8 , wherein the controller is further configured to:

transmit, via the transceiver, the HARQ positive or negative acknowledgement information for the downlink data, to the base station through the primary cell, in case that the expired TAT is not associated with the TAG including the serving cell.

14. The terminal of claim 8 , wherein the first TA information and the second TA information is received in timing advance command media access control (MAC) control element or in a random access response message.