Method and device for performing a logged measurement in a wireless communication system

1. A method for performing a logged measurement in wireless communication system, the method comprising:

receiving, by a user equipment (UE), a measurement configuration from a network;

logging, by the UE, an MDT (Minimization of Driving Tests) measurement; and

upon entering a state of resuming logging from a state of suspending logging, setting, by the UE, state transition information related to a state transition from the suspending logging to the resuming logging,

wherein the state transition information indicates a time spent related to the state transition.

2. The method of claim 1 , wherein the state transition information further includes an indicator indicating that the state transition has been made to the state of the resuming logging from the suspending logging.

3. The method of claim 2 , wherein the state transition information further includes a condition for the suspending logging.

4. The method of claim 3 , wherein the condition for suspending logging includes at least one of:

leaving, of the UE, from the RRC (radio resource control) state, which is configured to perform logging;

leaving, of the UE, from the RAT (Radio Access Technology), which is configured to perform logging;

leaving, of the UE, from logging area;

leaving, of the UE, from logging PLMN (Public Land Mobile Network);

leaving, of the UE, from a state of normal camping; and

whether total sum of the contents of the log, including the logged MDT measurement and the state transition information, reaches a predetermined value.

5. The method of claim 1 , wherein the state transition includes:

a state transition of the UE to a state in which logging is available; and

logging of MDT measurement by the UE when a condition for whether state transition occurred is a condition for resuming logging.

6. The method of claim 5 , wherein the state transition information includes an indicator indicating that a state transition has been made to the state in which logging is available.

7. The method of claim 6 , wherein the state transition information further includes the condition for resuming logging.

8. The method of claim 7 , wherein the condition for resuming logging includes at least one of:

entering, of the UE, to RRC (radio resource control), which is configured to perform logging;

entering, of the UE, to RAT (Radio Access Technology), which is configured to perform logging;

entering, of the UE, to a logging area;

entering, of the UE, to logging PLMN (Public Land Mobile Network); and

entering, of the UE, to a state of normal camping.

9. The method of claim 1 , wherein the UE is configured to periodically perform logging of the MDT measurement.

10. The method of claim 1 , wherein the UE is configured to perform logging based on a generation of events.

11. The method of claim 1 , further comprising:

receiving, by the UE, a request for reporting log contents from the network; and

transferring, by the UE, in response to the request for reporting, log contents including the logged MDT measurement and the state transition information to the network.

12. A device for performing logged measurement in wireless communication system, comprising:

a RF (Radio Frequency) unit configured to receive and transmit a radio signal; and

a processor connected to the RF unit, the processor configured to:

receive a measurement configuration from a network;

log an MDT (Minimization of Driving Tests) measurement; and

upon entering a state of resuming logging from a state of suspending logging, set state transition information related to a state transition from the suspending logging to the resuming logging,

wherein the state transition information indicates a time spent related to a state transition.