1. A method for performing a handover by a Mobile Subscriber Station (MSS) in a Broadband Wireless Access (BWA) communication system including a serving Base Station (BS) for providing a service to the MSS and a target BS adjacent to the serving BS, the method comprising the steps of;
receiving a handover request message from the serving BS, the handover request message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;
recognizing whether the serving BS retains the connection information according to a value of the resource remain type field;
transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
releasing connection with the serving BS upon transmitting the handover indication message;
determining a reentry to the serving BS during a handover to the target BS; and
reopening communication with the serving BS using the connection information, when the serving BS retains the connection information.', 'receiving a handover request message from the serving BS, the handover request message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;', 'recognizing whether the serving BS retains the connection information according to a value of the resource remain type field;', 'transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS;', 'releasing connection with the serving BS upon transmitting the handover indication message;', 'determining a reentry to the serving BS during a handover to the target BS; and', 'reopening communication with the serving BS using the connection information, when the serving BS retains the connection information.

2. The method as claimed in claim 1, wherein the time duration value represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS.

3. A method for performing a handover by a Mobile Subscriber Station (MSS) in a Broadband Wireless Access (BWA) communication system including a serving Base Station (BS) for providing a service to the MSS and a target BS adjacent to the serving BS, the method comprising the steps of:
transmitting a handover request message to the serving BS;
receiving a handover response message from the serving BS, the handover response message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;
recognizing whether the serving BS retains the connection information according to a value of the resource remain type field;
transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
releasing connection with the serving BS upon transmitting the handover indication message;
determining a reentry to the serving BS during a handover to the target BS; and
reopening communication with the serving BS using the connection information, when the serving BS retains the connection information.', 'transmitting a handover request message to the serving BS;', 'receiving a handover response message from the serving BS, the handover response message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;', 'recognizing whether the serving BS retains the connection information according to a value of the resource remain type field;', 'transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS;', 'releasing connection with the serving BS upon transmitting the handover indication message;', 'determining a reentry to the serving BS during a handover to the target BS; and', 'reopening communication with the serving BS using the connection information, when the serving BS retains the connection information.

4. The method as claimed in claim 3, wherein the time duration value represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS.

5. A method for performing a handover by a serving Base Station (BS) for providing a service to a Mobile Subscriber Station (MSS) in a Broadband Wireless Access (BWA) communication system including a target BS adjacent to the serving BS, the method comprising the steps of:
transmitting a handover request message to the MSS, the handover request message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;
receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;
releasing connection with the MSS upon receiving the handover indication message
retaining the connection information according to a value of the resource remain type field; and
reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'transmitting a handover request message to the MSS, the handover request message including a resource remain type field representing whether connection information having been set between the serving BS and the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;', 'receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;', 'releasing connection with the MSS upon receiving the handover indication message', 'retaining the connection information according to a value of the resource remain type field; and', 'reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.

6. The method as claimed in claim 5, wherein retaining the connection information starts from a point in time at which the handover indication message is received from the MSS, when the value of the resource remain type field represents retaining of the connection information.', '7. The method as claimed in claim 5, wherein the handover indication message includes a handover indication type represents releasing connection with the serving BS, that is HO_IND_type=00.', '8. The method as claimed in claim 5, wherein the time duration value represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS.', '9. The method as claimed in claim 5, wherein the connection information MSS is deleted when the value of the resource remain type field does not represent retaining of the connection information.', '10. A method for performing a handover by a serving Base Station (BS) for providing a service to a Mobile Subscriber Station (MSS) in a Broadband Wireless Access (BWA) communication system including a target BS adjacent to the serving BS, the method comprising the steps of:
receiving a handover request message from the MSS;
transmitting a handover response message to the MSS, the handover response message including a resource remain type field representing whether connection information having been set with the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;
receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;
releasing connection with the MSS upon receiving the handover indication message;
retaining the connection information according to a value of the resource remain type field; and
reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'receiving a handover request message from the MSS;', 'transmitting a handover response message to the MSS, the handover response message including a resource remain type field representing whether connection information having been set with the MSS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information;', 'receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;', 'releasing connection with the MSS upon receiving the handover indication message;', 'retaining the connection information according to a value of the resource remain type field; and', 'reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', '11. The method as claimed in claim 10, wherein retaining the connection information starts from a point in time at which the handover indication message is received from the MSS, when the value of the resource remain type field represents retaining of the connection information.', '12. The method as claimed in claim 10, wherein the handover indication message includes a handover indication type represents releasing connection with the serving BS, that is HO_IND_type=00.', '13. The method as claimed in claim 10, wherein the time duration value represents handover request message includes a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS.', '14. A system for performing a handover in a Broadband Wireless Access (BWA) communication system including a Mobile Subscriber Station (MSS), a serving Base Station (BS) for providing a service to the MSS, and a target BS adjacent to the serving BS, the system comprising:
an MSS for transmitting a handover request message to the serving BS, receiving a handover response message from the serving BS, the handover response message including a resource remain type field representing whether preset connection information is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, recognizing whether the serving BS retains the connection information according to a value of the resource remain type field, transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS, releasing connection with the serving BS upon transmitting the handover indication message, determining a reentry to the serving BS during a handover to the target BS, and reopening communication with the serving BS using the connection information, when the serving BS retains the connection information; and
the serving BS for receiving the handover request message from the MSS, transmitting the handover response message to the MSS, the handover response message including the resource remain type field representing whether the connection information having been set with the MSS is retained and the resource retain time field representing the time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS, releasing the connection with the MSS upon receiving the handover indication message, retaining the connection information according to the value of the resource remain type field, and reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'an MSS for transmitting a handover request message to the serving BS, receiving a handover response message from the serving BS, the handover response message including a resource remain type field representing whether preset connection information is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, recognizing whether the serving BS retains the connection information according to a value of the resource remain type field, transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS, releasing connection with the serving BS upon transmitting the handover indication message, determining a reentry to the serving BS during a handover to the target BS, and reopening communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'the serving BS for receiving the handover request message from the MSS, transmitting the handover response message to the MSS, the handover response message including the resource remain type field representing whether the connection information having been set with the MSS is retained and the resource retain time field representing the time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS, releasing the connection with the MSS upon receiving the handover indication message, retaining the connection information according to the value of the resource remain type field, and reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', '15. A system for performing a handover in a Broadband Wireless Access (BWA) communication system including a Mobile Subscriber Station (MSS), a serving Base Station (BS) for providing a service to the MSS, and a target BS adjacent to the serving BS, the system comprising:
an MSS for receiving a handover request message from the serving BS, the handover request message including a resource remain type field representing whether connection information having been set with the serving BS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, recognizing whether the serving BS retains the connection information according to a value of the resource remain type field, transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS, releasing connection with the serving BS upon transmitting the handover indication message, determining a reentry to the serving BS during a handover to the target BS, and reopening communication with the serving BS using the connection information, when the serving BS retains the connection information; and
the serving BS for transmitting the handover request message to the MSS, the handover request message including the resource remain type field representing whether the connection information having been set with the MSS is retained and the resource retain time field representing the time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS, releasing the connection with the MSS upon receiving the handover indication message, retaining the connection information according to the value of the resource remain type field, and reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'an MSS for receiving a handover request message from the serving BS, the handover request message including a resource remain type field representing whether connection information having been set with the serving BS is retained and a resource retain time field representing a time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, recognizing whether the serving BS retains the connection information according to a value of the resource remain type field, transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retaining of the connection information starts from a point in time at which the handover indication message is received by the serving BS, releasing connection with the serving BS upon transmitting the handover indication message, determining a reentry to the serving BS during a handover to the target BS, and reopening communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'the serving BS for transmitting the handover request message to the MSS, the handover request message including the resource remain type field representing whether the connection information having been set with the MSS is retained and the resource retain time field representing the time duration value during which the serving BS will retain the connection information when the resource remain type field represents retaining of the connection information, receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS, releasing the connection with the MSS upon receiving the handover indication message, retaining the connection information according to the value of the resource remain type field, and reopening communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.']