Patent ID: 7885656

Claim:
A method of performing a handover operation in a wireless communication system, the method comprising: receiving a handover message from a serving base station, wherein the serving base station determines that the handover needs to be performed by triggering a procedure to release a connection to the serving base station, and the handover message comprises information pertaining to one or more target base stations available for the handover; performing a scanning procedure to measure qualities of signals transmitted from neighboring base stations if the scanning procedure is required, wherein the scanning procedure comprises transmitting a scan request message for requesting a scanning interval to the serving base station 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 indication message to release the connection to the serving base station, wherein the handover indication message comprises a handover indication type which is set to release the serving base station and an identifier of a handover target base station; receiving fast ranging information from the handover target base station, 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 and receiving a ranging response message to establish an uplink synchronization and power adjustment with the handover target base station; and being released by the serving base station if a predetermined time duration passes after the serving base station receives the handover indication message.