Abstract: A method for controlling operation modes of a medium access control layer by a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station and a serving base station providing service to the mobile subscriber station is provided. The method includes the steps of: mode-transiting into an idle mode when there is no data transmission between the serving base station and the mobile subscriber station during a predetermined first time interval in an awake mode; detecting movement of the mobile subscriber station in the idle mode into another paging zone covering a target base station, which is different from a paging zone covering the serving base station; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected.

Abstract: A broadband wireless access communication system in which a subscriber station (SS) sends a serving base station (SBS) a handover request to neighbor base stations (NBSs) having a CINR satisfying a handover condition, in response to a handover scan request message, and performs the handover to a particular NBS that transmits a handover response. The SBS transmits the handover scan request message to the SS, sends a handover connection request to NBSs in an order determined by CINRs reported from the SS, and sends, to the SS, information on a particular NBS upon receiving a handover connection response with ACK information from the particular NBS. The particular NBS determines whether it can support handover of the SS, in response to the handover connection request, and sends the handover connection response with the ACK information to the SBS, if it can support handover of the SS.

Abstract: A method for measuring/reporting a channel quality in a broadband wireless access communication system. The method for reporting channel qualities of active BS and neighbor BSs measured by an MSS to the active BS when the MSS exists in a specific area covered by the active BS and neighbor BSs in a communication system includes receiving channel quality report information indicative of channel periods of the channel qualities from the active BS, and receiving channel quality measurement information associated with individual channel qualities of the neighbor BSs and the active BS from the active BS: measuring SINRs of the neighbor BSs and the active BS according to the channel quality measurement information; and reporting the measured SINRs of the neighbor BSs and the active BS to the active BS.

Abstract: Disclosed is a method for recognizing by a Mobile Subscriber Station (MSS) whether a serving Base Station (BS) retains connection information in a mobile communication system including the serving BS for providing a service to the MSS and a target BS adjacent to the serving BS. The method includes the steps of receiving a handover request message from the serving BS, the handover request message including a resource remain type field representing whether the connection information having been set with the serving BS is retained, and a resource retain time field representing a connection information-retaining time by the serving BS, and recognizing that the serving BS retains the connection information during a time determined by a value of the resource retain time field.

Abstract: Disclosed are a system and a method for selecting a new serving base station when a drop occurs in a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station, a serving base station communicating with the mobile subscriber station, and a plurality of neighbor base stations, different from the serving base station. The mobile subscriber station receives information related to the neighbor base stations from the serving base station communicating with the mobile subscriber station. The mobile subscriber station monitors the frequency bands of the neighbor base stations included in the information related to the neighbor base stations if the drop is detected in order to detect target base stations capable of serving as a new serving base station for communicating with the mobile subscriber station when the drop occurs in the mobile subscriber station according to a monitoring result for the frequency bands of the neighbor base stations.

Abstract: A method for measuring/reporting a channel quality in a broadband wireless access communication system. The method for reporting channel qualities of active BS and neighbor BSs measured by an MSS to the active BS when the MSS exists in a specific area covered by the active BS and neighbor BSs in a communication system includes the steps of: a) receiving channel quality report information indicative of channel periods of the channel qualities from the active BS, and receiving channel quality measurement information associated with individual channel qualities of the neighbor BSs and the active BS from the active BS; b) measuring SINRs of the neighbor BSs and the active BS according to the channel quality measurement information; and c) reporting the measured SINRs of the neighbor BSs and the active BS to the active BS.

Abstract: A method for controlling operation modes of a medium access control layer by a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station and a serving base station providing service to the mobile subscriber station is provided. The method includes the steps of: mode-transiting into an idle mode when there is no data transmission between the serving base station and the mobile subscriber station during a predetermined first time interval in an awake mode; detecting movement of the mobile subscriber station in the idle mode into another paging zone covering a target base station, which is different from a paging zone covering the serving base station; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected.

Abstract: A method for controlling operation modes of a medium access control layer by a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station and a serving base station providing service to the mobile subscriber station is provided. The method includes the steps of: mode-transiting into an idle mode when there is no data transmission between the serving base station and the mobile subscriber station during a predetermined first time interval in an awake mode; detecting movement of the mobile subscriber station in the idle mode into another paging zone covering a target base station, which is different from a paging zone covering the serving base station; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected.

Abstract: A method for controlling operation modes of a medium access control layer by a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station and a serving base station providing service to the mobile subscriber station is provided. The method includes the steps of: mode-transiting into an idle mode when there is no data transmission between the serving base station and the mobile subscriber station during a predetermined first time interval in an awake mode; detecting movement of the mobile subscriber station in the idle mode into another paging zone covering a target base station, which is different from a paging zone covering the serving base station; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected.

Abstract: A system and method for allocating a safety channel in a broadband wireless access (BWA) communication system including a serving base station (BS) for providing a service to a mobile station (MS) and neighbor BSs. Upon receiving a request for allocation of the safety channel from the MS, the serving BS sends a request for allocation of the safety channel to a target BS having the best channel condition among the neighbor BSs. Upon receiving information indicating possibility of allocating the safety channel from the target BS, the serving BS controls the MS such that the MS performs communication through the allocated safety channel. Upon detecting a need for receiving a safety channel, the MS sends, to the serving BS, information indicating that the MS should be allocated the safety channel, and receives a safety channel allocated according to a control signal from the serving BS.

Abstract: A method for supporting handover in a BWA communication system is provided. The system includes an MS, a serving BS, and a plurality of neighbor BSs. The coverage area of each of the BSs is divided into sectors using different subcarrier bands. The MS collects information broadcast from the serving BS on the serving BS and the neighbor BS, measures a signal level for each of the sectors of the serving BS and the neighbor BSs according to the collected information, and sends a handover request based on the measured signal level for each of the sectors. The serving BS broadcasts information on the serving BS and the neighbor BS to the MS, determines if the MS can perform a soft handover from its current sector to another sector upon receiving the handover request from the MS, and permits the MS to perform the soft handover if possible.

Abstract: In a broadband wireless access communication system which includes a mobile station, a serving base station and neighbor base stations located adjacent to the serving base station, the serving base station collects the information of the neighbor base stations, determines if the collected information of the neighbor base stations matches the information of the serving base station, sets up predetermined groups by classifying the neighbor base stations according to a result of the determination, and broadcasts a predetermined message including information of the setup groups, and the mobile station receives the predetermined message broadcasted, confirms the information of the neighbor base stations included in the received message, and performs location information update in accordance with the confirmed information.

Abstract: A system for a periodic ranging in a BWA communication system. In the system, a receiver in a sleep mode of a wireless communication system receives a sleep mode transition message, which including first information relating to a timing point at which the periodic ranging is performed, from a transmitter, transits to the sleep mode, and performs the periodic ranging at a timing point corresponding to the first information. Accordingly, the periodic ranging of the receiver in the sleep mode can be performed.

Abstract: A broadband wireless access (BWA) communication system includes a mobile subscriber station (MSS), a serving base station (BS) with which the MSS performs communication, and a plurality of neighbor BSs. The serving BS transmits, to the MSS, a handover request message including information on at least one recommended BS to which the MSS can perform a handover, among the neighbor BSs, and indication information indicating a fast handover, and transmits, to each of the recommended BSs, a handover confirm message indicating that the MSS will perform the fast handover.

Abstract: Disclosed is a method and a system for performing a handover capable of minimizing a service delay in a broadband wireless access communication system including a mobile station (MS), a serving base station (BS) providing services to the MS, and a target BS to which the MS hands over. The method comprises the steps of detecting that the handover from the serving BS to the target BS is necessary; and transmitting a request to the serving BS in order to perform portions of a handover process prior to the handover to the target BS.

Abstract: A method for managing a service flow of a mobile subscriber station (MSS) in a serving base station (BS) for a mobile communication system including the serving BS in communication with the MSS through a wireless access channel, and at least one active BS included in an active BS set of the MSS. Upon receiving a service flow management request from the MSS, the serving BS updates a service flow with the MSS, and transmits the updated service flow to the active BS using a predetermined message. Upon receiving a response message for the updated service flow from the active BS, the serving BS transmits service flow information of each active BS included in the response message to the MSS.

Abstract: A method for allocating a band Adaptive Modulation and Coding (AMC) channel in a wireless communication system that divides a full frequency band into a plurality of subcarrier bands and includes subchannels, each of which is a set of a predetermined number of neighbor subcarrier bands. Upon recognizing a need for a band AMC channel, a subscriber station (SS) sends a request for allocation of the band AMC channel to a base station (BS). Upon receiving the band AMC channel allocation request, the BS determines if it can allocate the band AMC channel requested by the SS, considering a resource situation of the BS, and transmits information on the determination to the SS.

Abstract: Disclosed is a method for allocating a safety channel in a wireless communication system which divides a full frequency band into a plurality of subcarrier bands and includes subchannels, each of which is a set of a predetermined number of subbands, each of which is a set of a predetermined number of contiguous subcarriers, where the subchannels include a safety subchannel allocated to particular subscriber stations (SSs), which is unused in a neighbor base station. The method comprises the steps of: transmitting, by the SS, its channel quality information to the base station (BS) when a channel quality of a subchannel allocated to the SS is less than to predetermined reference channel quality; and allocating a safety subchannel to the SS, by the BS upon receiving the channel quality information indicating that the channel quality of the subchannel is less than to the reference channel quality.

Abstract: A method supporting a Hybrid Automatic Repeat Request (HARQ) between a subscriber station and a base station in a broadband wireless access communication system including. The method includes the steps of: transmitting at least one H-ARQ enabled uplink burst from the subscriber station to the base station; generating ACK/NACK information according to the received HARQ enabled uplink burst at the base station; mapping the generated ACK/NACK information to a bitmap at the base station; transmitting the bitmap through a downlink information from the base station to the subscriber station.

Abstract: A divided Media Access Control (MAC) protocol structure, a data transmission and reception method, and a handover method and system using the structure in a wireless communication system for efficiently managing session information in handover of an MSS (Mobile Subscriber Station). In the MAC protocol structure, a MAC is divided into a MAC-high layer and a MAC-low layer. The MAC-high layer performs session information-related functions and the MAC-low layer performs functions sensitive to a time delay in relation to handover of an MSS. In the handover method, when an MSS in the wireless communication system performs handover between Access Points (APs), session information is managed at a fixed position by an Access Point Controller (APC) including an MAC-high layer or a serving AP. Therefore, the system load can be reduced and communication quality can be improved.