Apparatus and method for detecting cause of radio link failure or handover failure in mobile communication system

1. A method for operating a base station (BS) in a mobile communication system, the method comprising:

receiving a radio link failure (RLF) information report generated by a terminal after an RLF or a handover failure from another BS; and

determining a cause of the RLF or the handover failure based on the RLF information report,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.

2. The method of claim 1 , wherein the elapsed time is used to determine whether there is a recent handover of the terminal.

3. The method of claim 1 , wherein the determining of the cause of the RLF or the handover failure comprises determining the cause of the RLF or the handover failure based on a timer.

4. The method of claim 3 , wherein the timer is configured to measure an amount of time elapsed since the last handover until the RLF or the handover failure occurred.

5. The method of claim 1 , wherein the cause of the RLF or the handover failure is determined as the too early handover if the elapsed time is less than a threshold.

6. The method of claim 1 , wherein the cause of the RLF or the handover failure is determined as the too late handover if the elapsed time is greater than a threshold.

7. The method of claim 1 , wherein the cause of the RLF or the handover failure is determined as the handover to a wrong cell if the elapsed time is less than a threshold and the terminal receives a command for a handover from the another BS.

8. The method of claim 1 , wherein the cause of the RLF or the handover failure is determined as the handover to a wrong cell if the elapsed time is less than a threshold and the RLF or the handover failure occurs between the terminal and the another BS.

9. A method for operating a terminal in a mobile communication system, the method comprising:

performing a connection re-establishment or connection establishment in response to a radio link failure (RLF) or a handover failure; and

transmitting an RLF information report to a base station (BS) after the connection,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.

10. A method for operating a base station (BS) in a mobile communication system, the method comprising:

performing a connection re-establishment or connection establishment for a terminal in response to a radio link failure (RLF) or a handover failure in a cell of another BS;

receiving an RLF information report from the terminal; and

transmitting the RLF information report to the another BS,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.

11. A base station (B S) for use in a mobile communication system, the BS comprising:

a backhaul communication unit configured to receive a radio link failure (RLF) information report generated by a terminal after an RLF or a handover failure from another B S; and

a controller configured to determine a cause of the RLF or the handover failure based on the RLF information report,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.

12. The base station of claim 11 , wherein the elapsed time is used to determine whether there is a recent handover of the terminal.

13. The base station of claim 11 , wherein the controller is further configured to determine the cause of the RLF or the handover failure based on a timer.

14. The base station of claim 13 , wherein the timer is configured to measure an amount of time elapsed since the last handover until the RLF or the handover failure occurred.

15. The base station of claim 11 , wherein the controller is further configured to determine that the cause of the RLF or the handover failure is the too early handover if the elapsed time is less than a threshold.

16. The base station of claim 11 , wherein the controller is further configured to determine that the cause of the RLF or the handover failure is the too late handover if the elapsed time is greater than a threshold.

17. The base station of claim 11 , wherein the controller is further configured to determine that the cause of the RLF or the handover failure is handover to a wrong cell if the elapsed time is less than a threshold and the terminal receives a command for a handover from the another BS.

18. The base station of claim 11 , wherein the controller is further configured to determine that the cause of the RLF or the handover failure is handover to a wrong cell if the elapsed time is less than a threshold and the RLF or the handover failure occurs between the terminal and the another BS.

19. A terminal for use in a mobile communication system, the terminal comprising:

a controller configured to perform a connection re-establishment or connection establishment, if a radio link failure (RLF) or a handover failure occurs; and

a transmitter configured to transmit an RLF information report from the terminal to a base station (BS) after the process,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.

20. A base station (BS) for use in a mobile communication system, the BS comprising:

a controller configured to perform a connection re-establishment or connection establishment for a terminal in response to a radio link failure (RLF) or a handover failure in a cell of another BS;

a receiver configured to receive an RLF information report from the terminal; and

a backhaul communication unit configured to transmit the RLF information report to the another BS,

wherein the RLF information report comprises information regarding time elapsed since a reception of a command for a handover until the RLF or the handover failure, and

wherein the cause of the RLF or the handover failure comprises a too early handover, a too late handover, or a handover to a wrong cell.