Base station and operation method thereof

1. An operation method of a base station in a mobile communication network, the operation method comprising:

determining to disconnect a radio resource control (RRC) connection;

transmitting a RRC connection release message to a terminal;

maintaining the RRC connection during a second time before releasing the RRC connection after transmitting the RRC connection release message; and

receiving a RRC connection resume request message from the terminal,

wherein, when the RRC connection resume request message is received before a time of maintaining the RRC connection exceeds the second time, the RRC connection is not released.

2. The operation method according to claim 1 , wherein the RRC connection release message includes information on the second time.

3. The operation method according to claim 1 , wherein the RRC connection release message includes information on a timing advance (TA) of the terminal.

4. The operation method according to claim 3 , wherein, when the RRC connection resume request message is received without receiving a random access channel from the terminal after transmitting the RRC connection release message, information on a new TA is not transmitted.

5. An operation method of a terminal, the operation method comprising:

receiving a radio resource control (RRC) connection release message including information on a timing advance (TA) of the terminal from a base station;

maintaining a RRC connection between the terminal and the base station for a predetermined time after receiving the RRC connection release message;

releasing the RRC connection after a lapse of the predetermined time;

verifying a validity of the TA based on a traveled distance of the terminal; and

when the TA is valid, transmitting a RRC connection resume request message by using the TA.

6. A base station in a mobile communication network, the base station comprising a processor and a memory storing at least one instruction executed by the processor, wherein the at least one instruction is configured to:

determine to disconnect a radio resource control (RRC) connection;

transmit a RRC connection release message including information on a timing advance (TA) of a terminal to the terminal;

release the RRC connection with the terminal while maintaining an S1-U bearer set up between the base station and a serving gateway (S-GW); and

release the S1-U bearer after maintaining the S1-U bearer for a first time, wherein

when a RRC connection resume request message is received without receiving a random access channel from the terminal after transmitting the RRC connection release message, information on a new TA is not transmitted, and the RRC connection is resumed.

7. The base station according to claim 6 , wherein the at least one instruction is further configured to maintain the RRC connection for a second time before releasing the RRC connection after transmitting the RRC connection release message.

8. The base station according to claim 7 , wherein the RRC connection release message includes information on the second time.

9. The base station according to claim 6 , wherein the at least one instruction is further configured to transmit a user equipment (UE) context release request message to a mobility management entity (MME).