Method and device for performing handover in mobile communication system

A method performed by a base station in a wireless communication system, the method comprising:

• transmitting, to a terminal, measurement configuration information including measurement target information and measurement report trigger information;
• and
• receiving, from the terminal, a radio resource control (RRC) message including system frame number (SFN) offset information, the SFN offset information including first information indicating a difference between a first SFN of a first cell and a second SFN of a second cell and second information indicating a difference between a specific timing of the first cell and a specific timing of the second cell,
• wherein the SFN offset information is received, in case that reporting for the SFN offset information is indicated.

A terminal in a wireless communication system, the terminal comprising:

• a transceiver;
• and
• a controller configured to:
• receive, from a base station via the transceiver, measurement configuration information including measurement target information and measurement report trigger information,
• obtain system frame number (SFN) offset information, in case that the terminal is required to obtain the SFN offset information based on the measurement configuration information, and
• transmit, to the base station via the transceiver, a radio resource control (RRC) message including the SFN offset information, the SFN offset information including first information indicating a difference between a first SFN of a first cell and a second SFN of a second cell and second information indicating a difference between a specific timing of the first cell and a specific timing of the second cell.

A base station in a wireless communication system, the base station comprising:

• a transceiver;
• and
• a controller configured to:
• transmit, to a terminal via the transceiver, measurement configuration information including measurement target information and measurement report trigger information, and
• receive, from the terminal via the transceiver, a radio resource control (RRC) message including system frame number (SFN) offset information, the SFN offset information including first information indicating a difference between a first SFN of a first cell and a second SFN of a second cell and second information indicating a difference between a specific timing of the first cell and a specific timing of the second cell,
• wherein the SFN offset information is received, in case that reporting for the SFN offset information is indicated.