Apparatus and method for managing radio resource control connection in wireless communication system supporting device to device scheme

1. A method of an evolved NodeB (eNB) in a wireless communication system supporting a device to device (D2D) scheme, the method comprising:

starting an inactivity timer to control a user equipment (UE) to transit into a radio resource control (RRC) idle state after setting up an RRC connection with the UE;

allocating a D2D resource to the UE when a resource request message to request the D2D resource for a direct communication between UEs is received from the UE;

transmitting a resource response message including information related to the allocated D2D resource to the UE and stopping the inactivity timer; and

releasing the allocated D2D resource and restarting the inactivity timer based on a predetermined option.

2. The method of claim 1 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool which is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

releasing the allocated D2D resource and restarting the inactivity timer when a resource release request message to request a release for the allocated D2D resource is received from the UE; and

transmitting a resource release complete message indicating that the allocated D2D resource is released to the UE.

3. The method of claim 1 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool that is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

when a resource release indication message indicating that the allocated D2D resource will be released is transmitted to the UE, releasing the allocated D2D resource and restarting the inactivity timer.

4. The method of claim 1 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool that is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

when a time indicating a period during which the allocation for the D2D resource is maintained expires, releasing the allocated D2D resource and restarting the inactivity timer.

5. The method of claim 1 , further comprising:

when uplink traffic or downlink traffic for the UE occurs while running the inactivity timer, reconfiguring the inactivity timer; and

starting the reconfigured inactivity timer.

6. The method of claim 1 , further comprising:

releasing the RRC connection when the inactivity timer expires.

7. The method of claim 1 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

releasing the allocated D2D resource and restarting the inactivity timer when a discovery operation termination indication message indicating that the discovery operation is terminated is received from the UE; and

transmitting a discovery operation termination confirm message indicating that the allocated D2D resource is released to the UE in response to receiving the discovery operation termination indication message.

8. The method of claim 1 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

when a discovery operation termination indication message indicating that the discovery operation is terminated is transmitted to the UE, releasing the allocated D2D resource and restarting the inactivity timer.

9. The method of claim 1 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, releasing the allocated D2D resource and restarting the inactivity timer based on the predetermined option comprises:

when a discovery operation permission time during which the discovery operation is permitted expires, releasing the allocated D2D resource and restarting the inactivity timer.

10. The method of claim 9 , wherein information about the resource included in the common resource pool includes at least one of an index of the common resource pool, information related to a size of the common resource pool, and information related to a time during which allocation for the resource included in the common resource pool is maintained.

11. An evolved NodeB (eNB) in a wireless communication system supporting a device to device (D2D) scheme, the eNB comprising:

a receiver configured to receive a resource request message to request a D2D resource for a direct communication between user equipments (UEs) from a UE;

a controller configured to start an inactivity timer to control the UE to transit into a radio resource control (RRC) idle state after setting up an RRC connection with the UE, allocate a D2D resource to the UE when the resource request message is received, stop the inactivity timer when a resource response message including information related to the allocated D2D resource is transmitted, and release the allocated D2D resource and restart the inactivity timer based on a predetermined option; and

a transmitter configured to transmit the resource response message to the UE.

12. The eNB of claim 11 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a resource release request message to request a release for the allocated D2D resource is received from the UE, and

wherein the transmitter is configured to transmit a resource release complete message indicating that the allocated D2D resource is released to the UE.

13. The eNB of claim 11 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a resource release indication message indicating that the allocated D2D resource will be released is transmitted to the UE.

14. The eNB of claim 11 , wherein, when the D2D resource is a dedicated resource selected from a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a time indicating a period during which the allocation for the D2D resource is maintained expires.

15. The eNB of claim 11 , wherein the controller is configured to reconfigure the inactivity timer when uplink traffic or downlink traffic for the UE occurs while running the inactivity timer, and start the reconfigured inactivity timer.

16. The eNB of claim 11 , wherein the controller is configured to release the RRC connection when the inactivity timer expires.

17. The eNB of claim 11 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a discovery operation termination indication message indicating that the discovery operation is terminated is received from the UE, and

wherein the transmitter is configured to transmit a discovery operation termination confirm message indicating that the allocated D2D resource is released to the UE in response to receiving the discovery operation termination indication message.

18. The eNB of claim 11 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a discovery operation termination indication message indicating that the discovery operation is terminated is transmitted to the UE.

19. The eNB of claim 11 , wherein, when the D2D resource is a resource included in a common resource pool that is allocated for a discovery operation of the UE, the controller is configured to release the allocated D2D resource and restart the inactivity timer when a discovery operation permission time during which the discovery operation is permitted expires.

20. The eNB of claim 19 , wherein information about the resource included in the common resource pool includes at least one of an index of the common resource pool, information related to a size of the common resource pool, and information related to a time during which allocation for the resource included in the common resource pool is maintained.