Patent ID: 7890107

Claim:
A method for a mobile station (MS) for performing a handover operation in a wireless communication system, the method comprising: performing a scanning procedure to measure qualities of signals transmitted from neighboring base stations, wherein the scanning procedure comprises transmitting a scan request message for requesting a scanning interval to a serving base station (BS) and receiving a scan response message in response to the scan request message to assign the scanning interval for scanning the neighboring base stations; transmitting a handover request message to the serving BS if the MS has determined that a handover needs to be performed; receiving a handover response message including information pertaining to at least one neighboring handover target BS from the serving BS; transmitting a handover indication message to release a connection to the serving BS, wherein the handover indication message comprises a handover indication type which is set to release the serving BS and an identifier of the at least one neighboring handover target BS; receiving fast ranging information from the at least one neighboring handover target BS, wherein the fast ranging information comprises resources which are allocated for a ranging request; transmitting a ranging request message using the resources allocated by the fast ranging information to the at least one neighboring handover target BS and receiving a ranging response message from the at least one neighboring handover target BS to establish an uplink synchronization and power adjustment with the at least one neighboring handover target BS; and being released by the serving BS if a predetermined time duration passes after the serving BS receives the handover indication message.