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;
determining whether the serving BS retains the connection information according to a value of the resource remain type field and determining a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention 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 transmission of 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;', 'determining whether the serving BS retains the connection information according to a value of the resource remain type field and determining a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;', 'transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention 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 transmission of 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. 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;
determining whether the serving BS retains the connection information according to a value of the resource remain type field and determining a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention 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 transmission of 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;', 'determining whether the serving BS retains the connection information according to a value of the resource remain type field and determining a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;', 'transmitting a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention 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 transmission of 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.

3. 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;
receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;
releasing connection with the MSS upon reception of the handover indication message;
retaining the connection information according to a value of the resource remain type field during a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS; and
reopening communication with the MSS using the connection information, when the serving BS retains the connection information during 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;', 'receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;', 'releasing connection with the MSS upon reception of the handover indication message;', 'retaining the connection information according to a value of the resource remain type field during a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS; and', 'reopening communication with the MSS using the connection information, when the serving BS retains the connection information during a reentry of the MSS.', '4. The method as claimed in claim 3, 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 retention of the connection information.', '5. The method as claimed in claim 3, wherein the handover indication message includes a handover indication type (HO_IND_type) that represents release of the serving BS when the HO_IND_type=00.', '6. The method as claimed in claim 3, wherein the connection information is deleted when the value of the resource remain type field does not represent retention of the connection information.', '7. 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;
receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;
releasing connection with the MSS upon reception of the handover indication message;
retaining the connection information according to a value of the resource remain type field during a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS; and
reopening communication with the MSS using the connection information, when the serving BS retains the connection information during 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;', 'receiving a handover indication message including information reporting performance of a handover by the MSS from the MSS;', 'releasing connection with the MSS upon reception of the handover indication message;', 'retaining the connection information according to a value of the resource remain type field during a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS; and', 'reopening communication with the MSS using the connection information, when the serving BS retains the connection information during a reentry of the MSS.', '8. The method as claimed in claim 7, 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 retention of the connection information.', '9. The method as claimed in claim 7, wherein the handover indication message includes a handover indication type (HO_IND_type) that represents release of the connection with the serving BS when the HO_IND_type=00.', '10. 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 adapted to:
transmit a handover request message to the serving BS,
receive 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;
determine whether the serving BS retains the connection information according to a value of the resource remain type field and determine a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
release connection with the serving BS upon transmission of the handover indication message;
determine a reentry to the serving BS during a handover to the target BS; and
reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and

a serving BS adapted to:
receive the handover request message from the MSS;
transmit the handover response message to the MSS, the handover response message including the resource remain type field;
receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;
release the connection with the MSS upon reception of the handover indication message;
retain the connection information according to the value of the resource remain type field during the system retaining time; and
reopen communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'an MSS adapted to:', 'transmit a handover request message to the serving BS,', 'receive 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;
determine whether the serving BS retains the connection information according to a value of the resource remain type field and determine a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
release connection with the serving BS upon transmission of the handover indication message;
determine a reentry to the serving BS during a handover to the target BS; and
reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'determine whether the serving BS retains the connection information according to a value of the resource remain type field and determine a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;', 'transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;', 'release connection with the serving BS upon transmission of the handover indication message;', 'determine a reentry to the serving BS during a handover to the target BS; and', 'reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'a serving BS adapted to:
receive the handover request message from the MSS;
transmit the handover response message to the MSS, the handover response message including the resource remain type field;
receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;
release the connection with the MSS upon reception of the handover indication message;
retain the connection information according to the value of the resource remain type field during the system retaining time; and
reopen communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', 'receive the handover request message from the MSS;', 'transmit the handover response message to the MSS, the handover response message including the resource remain type field;', 'receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;', 'release the connection with the MSS upon reception of the handover indication message;', 'retain the connection information according to the value of the resource remain type field during the system retaining time; and', 'reopen communication with the MSS using the connection information, when the serving BS retains the connection information in a reentry of the MSS.', '11. 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 adapted to:
receive 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;
recognize whether the serving BS retains the connection information according to a value of the resource remain type field and recognizing a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
release connection with the serving BS upon transmission of the handover indication message;
determine a reentry to the serving BS during a handover to the target BS; and
reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and

a serving BS adapted to:
transmit the handover request message to the MSS, the handover request message including the resource remain type field;
receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;
release the connection with the MSS upon reception of the handover indication message;
retain the connection information according to the value of the resource remain type field during the system retaining time; and
reopen communication with the MSS using the connection information, when the serving BS retains the connection information during a reentry of the MSS.', 'an MSS adapted to:
receive 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;
recognize whether the serving BS retains the connection information according to a value of the resource remain type field and recognizing a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;
transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;
release connection with the serving BS upon transmission of the handover indication message;
determine a reentry to the serving BS during a handover to the target BS; and
reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'receive 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;', 'recognize whether the serving BS retains the connection information according to a value of the resource remain type field and recognizing a resource retain time during which the serving BS will retain the connection information when the resource remain type field represents retention of the connection information, wherein the resource retain time represents a system retaining time representing a pre-negotiated time agreed to when a registration is performed between the serving BS and the MSS;', 'transmit a handover indication message to the serving BS, the handover indication message including information reporting performance of the handover and representing that retention of the connection information starts from a point in time at which the handover indication message is received by the serving BS;', 'release connection with the serving BS upon transmission of the handover indication message;', 'determine a reentry to the serving BS during a handover to the target BS; and', 'reopen communication with the serving BS using the connection information, when the serving BS retains the connection information; and', 'a serving BS adapted to:
transmit the handover request message to the MSS, the handover request message including the resource remain type field;
receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;
release the connection with the MSS upon reception of the handover indication message;
retain the connection information according to the value of the resource remain type field during the system retaining time; and
reopen communication with the MSS using the connection information, when the serving BS retains the connection information during a reentry of the MSS.', 'transmit the handover request message to the MSS, the handover request message including the resource remain type field;', 'receive the handover indication message including the information reporting performance of the handover by the MSS from the MSS;', 'release the connection with the MSS upon reception of the handover indication message;', 'retain the connection information according to the value of the resource remain type field during the system retaining time; and', 'reopen communication with the MSS using the connection information, when the serving BS retains the connection information during a reentry of the MSS.']