Abstract: A system and method for performing a handover in a wireless communication system are provided. In the system and method an MS receives a mobile neighbor advertisement message including PDR information about a serving BS and neighbor BSs from the serving BS, selects candidate BSs based on a location of the MS and the PDR information, determines communication states of the candidate BSs, determines a target BS for the handover according to the determined communication states, and performs the handover to the target BS.

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.

Abstract: Method and system by which a base station without a Global Positioning System (GPS) receiver acquires time synchronization in a Broadband Wireless Access (BWA) communication system. The method includes scanning neighbor base stations around a first base station and requesting time synchronization information from the scanned neighbor base stations by the first base station; receiving responses from predetermined neighbor base stations having already acquired time synchronization from among the neighbor base stations, the responses including time synchronization information of the predetermined neighbor base stations; and selecting a second base station from among the predetermined neighbor base stations and acquiring time synchronization based on the time synchronization information of the second base station.

Abstract: In a method of configuring connection identifier (CID) update information in a broadband wireless access (BWA) communication system where each service between an mobile station (MS) and a base station (BS) has a unique CID, a registration request message is received from the MS, requesting updating of at least one old CID used for the MS. The CID update information is configured to include a bitmap area indicating whether a service corresponding to the at least one old CID is available, and a new CID area including at least one new CID in correspondence with a predetermined bit value in the bitmap area.

Abstract: In a method of configuring connection identifier (CID) update information in a broadband wireless access (BWA) communication system where each service between an mobile station (MS) and a base station (BS) has a unique CID, a registration request message is received from the MS, requesting updating of at least one old CID used for the MS. The CID update information is configured to include a bitmap area indicating whether a service corresponding to the at least one old CID is available, and a new CID area including at least one new CID in correspondence with a predetermined bit value in the bitmap area.

Abstract: Provided is a method supporting a Hybrid Automatic Repeat Request (HARQ) between a subscriber station and a base station in a broadband wireless access communication system. The method includes transmitting at least one HARQ enabled uplink burst from the subscriber station to the base station; generating ACKnowledgment/Negative ACKnowledgment (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; and transmitting the bitmap through a downlink information from the base station to the subscriber station.

Abstract: A method for controlling a sleep-mode operation in a communication system is provided, in which a Mobile Station (MS) transitions to an awake state in a listening interval of the sleep mode, performs one of a first operation, a second operation, and a third operation in the awake state, and transitions to a sleep state if the MS determines that there is no data to transmit to a BS and no data to receive from the Base Station (BS) after the one operation is performed. The first operation is for receiving data from the BS, the second operation is for transmitting data to the BS, and the third operation is receiving data from the BS and transmitting data to the BS.

Abstract: An apparatus and method for providing an urgent call service in a communication system are provided. A base station receives from a mobile station a message ranging request with a Medium Access Control (MAC) address in which a priority is set. If the priority set in the MAC address is a highest priority, the base station processes the message ranging request with the highest priority and provides the urgent call service to the mobile station. Upon detecting a request for the urgent call service, the mobile station sends a message ranging request to a base station using a Medium Access Control (MAC) address in which a highest priority is set, and receives the urgent call service in response to the message ranging request.

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 allocating a safety channel to a handover subscriber station (SS) for data communication in an Orthogonal Frequency Division Multiple Access (OFDMA) communication system. In the method, a base station (BS) determines a bin offset indicating a safety channel to be allocated to the handover SS and the number of subchannels every frame, generates a MAP information element (IE) with a set indicator indicating allocation of the safety channel, the MAP IE including SS identifier information indicating the handover SS, information on the determined bin offset and information on the determined number of subchannels, and transmits the generated MAP IE at a MAP IE transmission time in the frame. The handover SS receives the MAP IE from the BS every frame, and transmits/receives data for a predetermined number of frames in the allocated safety channel according to the MAP IE.

Abstract: A method for providing service in a communication system. A base station (BS) receives a request message for requesting a service from a mobile station (MS) located in a first service zone; and transmits to the MS a response message including information on a BS located in a service zone supporting the requested service. The MS transmits a request message for requesting a service to the BS located in the first service zone, and receives a response message including information on a BS located in a service zone supporting the requested service, from the BS located in the first service zone.

Abstract: Disclosed is a system and method for performing soft handover in a broadband wireless access communication system. An anchor base station transmits first information including channel assignment information of an active non-anchor base station when it is determined that a mobile station is to perform the soft handover, and when there are signals to be transmitted to the mobile station from the non-anchor base station, the non-anchor base station transmits second information including channel assignment information of the anchor base station when it is determined that the mobile station is to perform the soft handover, and when there are signals to be transmitted to the mobile station from the anchor base station, and the mobile station receives signals from the anchor base station and the non-anchor base station corresponding to the first information and the second information when it is determined that the mobile station is to perform the soft handover.

Abstract: Disclosed is a system and method for performing soft handover in a broadband wireless access communication system. An anchor base station transmits first information including channel assignment information of an active non-anchor base station when it is determined that a mobile station is to perform the soft handover, and when there are signals to be transmitted to the mobile station from the non-anchor base station, the non-anchor base station transmits second information including channel assignment information of the anchor base station when it is determined that the mobile station is to perform the soft handover, and when there are signals to be transmitted to the mobile station from the anchor base station, and the mobile station receives signals from the anchor base station and the non-anchor base station corresponding to the first information and the second information when it is determined that the mobile station is to perform the soft handover.

Abstract: An apparatus and method for using an Automatic Repeat reQuest (ARQ) in a Broadband Wireless Access (BWA) communication system are provided. In a transmitting method of a wireless communication system, a Media Access Control (MAC) layer creates a packet and transmits it to a physical layer, the physical layer generates a Hybrid ARQ (HARQ) burst using the packet received from the MAC layer and transmits it, the physical layer generates a HARQ ending signal and transmits it to the MAC layer when HARQ transmission of the packet is discontinued, and the MAC layer drives an ARQ retransmission timer for the packet in response to the HARQ ending signal.

Abstract: In a communication system, second encryption information is generated using first encryption information when data to be transmitted is generated. The data is encrypted using the second encryption information and third encryption information. A signal including the encrypted data and the first encryption information is generated and transmitted.

Abstract: An apparatus and a method for processing media data so that an MBS is supported in a BWA communication system. A traffic processing method supports an MBS in a broadband wireless access communication system having a number of base stations and at least one contents server for transmitting various media traffics to the base stations. The method includes reserving a resource for MBS burst assignment with regard to the base stations; requesting the contents server to provide a traffic to be transmitted to the base stations when the resource has been successfully reserved; shaping a media traffic transmitted by the contents server; and transmitting the media traffic to the base stations.

Abstract: A method of providing LBS (Location-Based Services) in a mobile communication system is provided. A Mobile Station (MS) entering an incoming call rejection service area is precluded from receiving incoming calls. When a call connection to the MS is requested, the call connection is blocked from the MS, and a call connection unavailable message is transmitted to a calling MS.

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 is provided for transmitting a MAP message in a wireless communication system. A base station transmits the MAP message including operation mode information indicating a data burst allocation scheme, to a mobile station. The mobile station identifies a data burst according to the operation mode information included in the MAP message received from the base station.

Abstract: A method and system for allocating data bursts in a wireless communication system. The system has a frame set by a symbol interval axis and a frequency band axis. The frame includes a first region in which a MAP message is transmitted and a second region to which the data bursts are allocated. A third region based on a symbol interval and a frequency band is set in the second region. The data bursts are sequentially allocated to the third region from a first symbol interval along the frequency band axis.