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: A system and method for transmitting a traffic indication message in a Broadband Wireless Access communication system. A base station (BS) transmits the traffic indication message to mobile subscriber stations (MSSs). The traffic indication message includes information on a number of MSS groups and information on a number of traffic indication indexes, each of the MSS groups includes a predetermined number of MSSs, and each of the traffic indication indexes is assigned to each of the MSS groups, and includes a bitmap including a predetermined number of bits. The predetermined number of bits is identical to the number of the MSSs included in each of the MSS groups, each of the predetermined number of the bits is assigned to each of the MSSs included in each of the MSS groups, and represents operation instruction information for each of the MSSs.

Abstract: A method for determining a number of ranging slots by a base station (BS) in a broadband wireless access (BWA) communication system. The method includes counting the number of mobile stations (MSs) that succeeded in ranging in a current frame, determining a ranging slot occupation ratio in the current frame, comparing a ranging slot occupation ratio of a previous frame with the ranging slot occupation ratio of the current frame, detecting an increase in the number of ranging-requesting MSs, if the ranging slot occupation ratio of the current frame is greater than the ranging slot occupation ratio of the previous frame, and determining the number of ranging slots of a next frame such that the number of ranging slots of the next frame is greater than the number of ranging slots of the current frame.

Abstract: Disclosed is a system and a method for controlling a handover of a mobile subscriber station in a broadband wireless access communication system. When serving base station determines to perform a handover of the mobile subscriber station, neighbor base stations to which the mobile subscriber station can be handed over, from among neighbor base stations of the mobile subscriber station, are determined based on a service quality level of service being currently provided to the mobile subscriber station. A handover request signal containing information related to the determined neighbor base station to which the mobile subscriber station can be handed over is transmitted to the mobile subscriber station.

Abstract: A system and method for updating a sleep identifier (SLPID) of a mobile station (MS) in a broadband wireless access (BWA) communication system having a sleep mode in which there is no transmission data and an awake mode in which there is transmission data. Upon recognizing a need to update an SLPID allocated to an MS in the sleep mode in the initial phase of the sleep mode, a base station (BS) reallocates a new SLPID to be allocated to the MS and transmits SLPID update information to the MS. Upon receiving the SLPID update information for its current SLPID during the sleep mode, the MS updates its current SLPID with the reallocated SLPID according to the received update information.

Abstract: In a communication system, a mobile station (MS) sends a target base station (BS) a notification indicating that it is to perform a handover from a serving BS to the target BS. The target BS transmits to the MS handover process optimization information indicating a possibility of omitting at least one process required by the MS to perform a network re-entry operation with the target BS according to the handover notification from the MS. The MS receives the handover process optimization information and performs a network re-entry operation with the target BS according to the handover process optimization information.

Abstract: A communication system using an OFDM (Orthogonal Frequency Division Multiplexing) scheme. The communication system receives neighbor BS (Base Station) information of a plurality of neighbor BSs associated with a plurality of cells adjacent to a cell and uplink-associated information needed for transmitting data to the first BS from the first BS, requests synchronization information needed for establishing synchronization acquisition between the SS and the first BS from the first BS, monitors the plurality of neighbor BSs on the basis of the neighbor BS information associated with the neighbor BSs, and establishing a handoff with the second BS, which is one of the neighbor BSs, based on the result of the neighbor BSs.

Abstract: A system and method for controlling data rates of a reverse packet data in mobile communication system for transmitting reverse packet data from a mobile station to a base station over a reverse packet data channel at a plurality of data rates. The present invention provides an apparatus and method for improving throughput of an entire system by enabling a base station's scheduler to rapidly assign reverse resource for a mobile station that has completed its data transmission to other mobile stations.

Abstract: A broadband wireless access communication system including a serving BS which broadcasts a MOB_NBR-ADV message to an MS is provided. A method for configuring the MOB_NBR-ADV message is also provided, and includes adding a specific field, which represents whether at least one information field constituting the MOB_NBR-ADV message exists, to the MOB_NBR-ADV message, determining if at least one information field is included in the MOB_NBR-ADV message, and determining a bit value of the specific field according to whether at least one information field is included in the MOB_NBR-ADV message.

Abstract: An information frame of a new format transmitted according to a radio link protocol (RLP), and a device and method for transmitting and receiving the information frame in a mobile communication system. The information frame is comprised of a plurality of consecutive multiplex frames each having a given length. The multiplex frames each are comprised of a header and a succeeding RLP frame, and the RLP frame includes transmission data. At least one of the multiplex frames is comprised of a plurality of sub-multiplex frames, and each sub-multiplex frame is comprised of a header including an RLP service identifier field and a length indication field for indicating a length of the transmission data, and a data block associated to the succeeding RLP frame.

Abstract: In a BWA communication system, an MSS changes its connection from the serving BS to the target BS, and sends the target BS a report indicating that the MSS will change its connection upon detecting occurrence of a pingpong effect in a process of performing a network re-entry operation with the target BS. The target BS sends the serving BS a notification indicating that the MSS will change its connection. Upon receiving from the MSS a report indicating that it will change its connection to the serving BS, the serving BS allocates a contention-free-based ranging resource to the MSS so that the MSS connects a communication service with the serving BS using the contention-free-based ranging resource, minimizing a service delay.

Abstract: A system and method for updating a sleep identifier (SLPID) of a mobile station (MS) in a broadband wireless access (BWA) communication system having a sleep mode in which there is no transmission data and an awake mode in which there is transmission data. Upon recognizing a need to update an SLPID allocated to an MS in the sleep mode in the initial phase of the sleep mode, a base station (BS) reallocates a new SLPID to be allocated to the MS and transmits SLPID update information to the MS. Upon receiving the SLPID update information for its current SLPID during the sleep mode, the MS updates its current SLPID with the reallocated SLPID according to the received update information.

Abstract: An apparatus and method for transmitting and receiving a signal according to a change of downlink channel information by a mobile station in a broadband wireless access communication system. The method includes: detecting the change of the downlink channel information; receiving a report from a base station that there is data for the mobile station; and reporting the change of the downlink channel information to the base station, so that the base station and the mobile station have same downlink channel information.

Abstract: A system and method for dynamically allocating channels in a wireless communication system including multiple sub-channels and multiple frame cells, each of the sub-channels being an assembly including a preset number of sub-frequency bands divided from an overall frequency band, the frame cells using each of the sub-channels as a basic transmission unit and having a frequency domain and a time domain occupied by the sub-channels. A mobile station transmits channel quality information of frame cells to an access point. An access router transmits channel allocation information about the multiple frame cells and sub-channels determined according to the received channel quality information to the access point, and the access point receives the channel allocation information about the multiple frame cells and sub-channels, compares the channel allocation information with newest channel quality information, and allocates a sub-channel of a frame cell selected according to the comparison to the mobile station.

Abstract: Disclosed are a system and a method for assigning ranging codes in a communication system. The communication system classifies rangings between a transmission unit and a reception unit of the broadband wireless access communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a drop ranging. The communication system creates a first number of ranging codes used for the rangings and assigning a second number of ranging codes selected from the first number of ranging codes as drop ranging codes used for the drop ranging.

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: Disclosed is a method for controlling an operational state of a medium access control layer in a broadband wireless access communication system. The method includes the steps of performing an uplink access of a contention-based scheme to an access point using resources required to perform the uplink access according to the contention-based scheme when data to be transmitted in an access state is detected, and being allocated resources required to perform an uplink access of a contention-free scheme from the access point in a case of failing in the uplink access of the contention-based scheme; and performing a state transition from the access state into the traffic state in a case of having been allocated the resource required for the contention-free scheme, and performing the uplink access of the contention-free scheme to the access point using the allocated resource in the traffic state.

Abstract: A system and method for performing a handover operation in a broadband wireless access (BWA) communication system. The BWA communication system includes a serving BS (Base Station),(Subscriber Station), and a plurality of neighbor BSs adjacent to the serving BS. The SS handover method upon receiving a handover request from the SS in the BWA communication system includes the steps of: a) receiving from the serving BS information of the plurality of neighbor BSs; b) measuring CINRs (Carrier to Interference and Noise Ratios) of pilot signals transferred from the neighbor BSs upon receipt of the neighbor BSs information; c) transmitting to the serving BS a handover request signal along with pilot signal CINR information of the neighbor BSs; d) upon receipt of the handover request signal, receiving from the serving BS information of a handover enable target BS contained in the neighbor BSs; and e) performing a handover function from the serving BS to the target BS.

Abstract: Disclosed is a system and a method for controlling a handover of a mobile subscriber station in a broadband wireless access communication system. When serving base station determines to perform a handover of the mobile subscriber station, neighbor base stations to which the mobile subscriber station can be handed over, from among neighbor base stations of the mobile subscriber station, are determined based on a service quality level of service being currently provided to the mobile subscriber station. A handover request signal containing information related to the determined neighbor base station to which the mobile subscriber station can be handed over is transmitted to the mobile subscriber station.

Abstract: Dynamically allocating a frame cell (FC)/subchannel in a mobile communication system by an access point that receives channel quality information (CQIs) fed back from access terminals, determines a modulation and coding scheme (MCS) to be applied to the access terminals based on the CQIs, and if access terminals whose FCs/subchannels must be changed are detected from the access terminals, sends an FC/subchannel change request to an access router. The access router allocates an FC/subchannel set by selecting a number of FCs/subchannels according to the FC/subchannel change request, and transmits information on the allocated FC/subchannel set to the access point. The access point selects and allocates a particular FC/subchannel from among FCs/subchannels in the FC/subchannel set information to the access terminals whose FCs/subchannels must be changed, based on CQIs last received from the access terminals.