Handover method in a wireless mobile communication system and a system therefor

A method for supporting handover of a mobile station by a target base station in a wireless mobile communication system, the method comprising:

• receiving a handover confirmation message that indicates the mobile station to be handed over to the target base station;
• transmitting a ranging response message, that comprises authentication information required for the mobile station to authenticate the target base station, to the mobile station;
• allocating fast ranging resources to the mobile station;
• and
• receiving a ranging response acknowledgement (ACK) message, that comprises authentication information required for the target base station to authenticate the mobile station, from the mobile station after allocating the fast ranging resources.

A wireless mobile communication system comprising:

• a mobile station;
• a serving base station which is providing a service to the mobile station;
• and
• a target base station to which the mobile station is to be handed over,
• wherein the mobile station transmits a handover indication message comprising information about the target base station to the serving base station, receives a ranging response message comprising authentication information required for the mobile station to authenticate the target base station from the target base station, being allocated fast ranging resources from the target base station, and transmits a ranging response acknowledgement (ACK) message comprising authentication information required for the target base station to authenticate the mobile station to the target base station.