Method and apparatus for performing handover

A method for performing a handover by a destination base station, the method comprising:

• receiving a handover request message from a destination base station gateway, the handover request message for requesting a handover to the destination base station of a user equipment (UE) receiving a service from a source base station;
• allocating a resource to the UE;
• transmitting a handover request acknowledgement message to the destination base station gateway, the handover request acknowledgement message indicating that the handover to the destination base station of the UE is possible;
• and
• when a handover acknowledgement message is received from the UE, the handover acknowledgement message indicating that the handover to the destination base station of the UE is to be performed, transmitting to the destination base station gateway a handover notification message for notifying the handover of the UE,
• wherein the handover request message comprises a Next-hop Chaining Counter (NCC) of the source base station and an encryption key for a communication between the UE and the destination base station, and
• wherein the NCC and the encryption key are transmitted to the destination base station gateway from a source base station gateway, after the NCC and the encryption key are delivered to the source base station gateway from the source base station.

A source base station comprising:

• a receiver configured to receive a handover command message, indicating a performing of a handover to a destination base station of a user equipment (UE), from a source base station gateway, and receive a UE context release command message from the source base station gateway;
• a controller configured to release a context of the UE when the UE context release command message is received from the source base station gateway;
• and
• a transmitter configured to transmit to the source base station gateway a handover requirement message for the handover to the destination base station of the UE, transmit the handover command message to the UE when the handover command message is received from the source base station gateway, and transmit to the source base station gateway a UE context release completion message representing that the context of the UE is released when the context of the UE is released according to a reception of the UE context release command message,
• wherein the handover requirement message comprises a Next-hop Chaining Counter (NCC) and an encryption key for a communication between the UE and the destination base station, and
• wherein the NCC and the encryption key are transmitted to the destination base station from a destination base station gateway, after the NCC and the encryption key are delivered to the destination base station gateway from the source base station gateway.

A destination base station comprising:

• a receiver configured to receive a handover request message from a destination base station gateway, the handover request message representing a message for requesting a handover to the destination base station of a user equipment (UE) receiving a service from a source base station, and receive a handover acknowledgement message from the UE, the handover acknowledgement message indicating that the handover to the destination base station of the UE is to be performed;
• a controller configured to allocate a resource the UE when the handover request message is received;
• and
• a transmitter configured to transmit a handover request acknowledgement message to the destination base station gateway when the resource is allocated to the UE, the handover request acknowledgement message indicating that the handover to the destination base station of the UE is possible, and transmit to the destination base station gateway a handover notification message for notifying the handover of the UE when the handover acknowledgement message is received,
• wherein the handover request message comprises a Next-hop Chaining Counter (NCC) of the source base station and an encryption key for a communication between the UE and the destination base station, and
• wherein the NCC and the encryption key are transmitted to the destination base station gateway from a source base station gateway, after the NCC and the encryption key are delivered to the source base station gateway from the source base station.