Abstract: A broadband wireless access (BWA) communication system including a serving BS for servicing an SS in at least one of a plurality of sub-carrier frequency bands, and a plurality of neighbor BSs adjacent to the serving BS. The SS measures CINRs of frequency band signals from the neighbor BSs, requests a handoff for a target BS having the highest CINR to the serving BS, transitions to the frequency band of the target BS, and acquires synchronization to the target BS. The SS transmits ranging information to the target BS in a ranging information region assigned by the target BS, receives from the target BS connection ID information between the target BS and the SS, transmits a handoff registration request message to the target BS according to the connection ID information, and receives a response message for the handoff registration request message from the target BS.

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: A method and apparatus for defining at least one subcarrier as a subchannel, dividing a total frequency band into a plurality of subchannels, and allocating the subchannels to at least one mobile station in an OFDMA mobile communication system. The method includes receiving channel state information; comparing the received channel state information with a predetermined threshold, calculating an average occurrence length of a case in which the received channel state information is greater than the threshold, calculating a state hold prediction value, calculating an estimation value, sorting the calculated estimation values according to subchannels in order of their levels, and allocating subchannels according to the at least one mobile station in the sorted order.

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 PLP transmitting method in a mobile communication system is provided. A base station determines a forward data rate according to DRC information received from a mobile station, reads out temporary EPs of a maximum total size from the buffers, determines whether the temporary EPs can be transmitted at the data rate, forms a combination of logical EPs from the temporary EPs if the temporary EPs can be transmitted at the data rate and the total size of the temporary EPs is equal to or greater than a threshold, and transmits the logical EPs in a PLP.

Abstract: A reverse link controlling method in a mobile communication system. To increase or decrease a reverse data rate, an MS receives threshold power information indicating a power threshold for a pilot channel from the BS and measures the reception power of the pilot channel received from the BS. When the MS is supposed to increase or decrease the current data rate, it increases the current data rate by two levels or decreases the current data rate by one level if the pilot reception power is higher than the power threshold, and increases the current data rate by one level or decreases the current data rate by two levels if the pilot reception power is equal to lower than the power threshold.

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: A reverse transmission controlling method in a mobile communication system, after receiving forward information, commanding the increase or decrease of the reverse data rate received on a forward control channel from a base station, a mobile station determines whether the previous rate increase available information transmitted to the base station on a reverse control channel before reception of the forward information indicates that a reverse data rate increase is available, if the forward information commands a reverse data rate increase. The mobile station increases the current reverse data rate to a data rate equal to or less than a maximum reverse data rate if the rate increase available information indicates that the reverse data rate increase is available, and transmits reverse data at the increased reverse data rate.

Abstract: Disclosed herein is a ranging method for a mobile communication system based on an OFDMA (Orthogonal Frequency Division Multiple Access) scheme. In the communication system for classifying a ranging procedure between a transmission side and reception sides into an initial ranging process, a bandwidth request ranging process, and a periodic ranging process, the ranging method includes the steps of determining the number of initial RCs(ranging codes) for the initial ranging process, the number of bandwidth request RCs for the bandwidth request ranging process, and the number of periodic RCs for the periodic ranging process, determining a backoff value of the periodic RCs according to the number of the periodic RCs, and sending the initial RCs, the bandwidth request RCs, the periodic RCs, and the backoff value of the periodic RCs to the reception sides.

Abstract: A reverse link controlling method in a mobile communication system. To increase or decrease a reverse data rate, an MS receives threshold power information indicating a power threshold for a pilot channel from the BS and measures the reception power of the pilot channel received from the BS. When the MS is supposed to increase or decrease the current data rate, it increases the current data rate by two levels or decreases the current data rate by one level if the pilot reception power is higher than the power threshold, and increases the current data rate by one level or decreases the current data rate by two levels if the pilot reception power is equal to lower than the power threshold.

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: 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: A reverse data transmission apparatus and method in a mobile communication system. A mobile station receives information about an MADR (Maximum Allowable Data Rate) from a base station in a first predetermined frame period, determines a data rate equal to or lower than the MADR, and requests the determined data rate to the base station. If an MADR received from the base station in a second frame period following the first frame period is higher than the requested data rate, the mobile station starts data transmission. Then, the mobile station measures a traffic to pilot ratio (T/P) from the base station and controls the data rate according to the T/P during data transmission.

Abstract: A mobile station in a control hold mode wakes up at a time slot on a wake-up channel received from a base station, assigned thereto, and detects at least one predetermined indicator bit. If the detected indicator bit indicates that the base station has data to transmit, the mobile station starts monitoring a forward packet data control channel from the base station, in order to determine whether to make a transition to an active mode. Otherwise, if the detected indicator bit indicates that the base station has no data to transmit, the mobile station maintains the control hold mode, thus preventing unnecessary power consumption.

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 and apparatus for retransmitting data in a mobile communication system wherein a receiver determines whether an initial data block received from a transmitter has an error. Upon detecting an error from the initial data block, the receiver estimates a current channel state and determines a retransmission frequency and a power level of the initial data block according to the estimated current channel state. Thereafter, the receiver transmits a retransmission request message of the initial data block together with the determined retransmission frequency and the determined power level to the transmitter. The transmitter retransmits the initial data block as many times as the retransmission frequency at the requested power level. The receiver then determines whether the retransmitted data blocks have errors, and provides the retransmitted data blocks to an upper layer upon failure to detect errors from the retransmitted data blocks.

Abstract: A call admission method considering call characteristics and the service level of a subscriber terminal in a CDMA mobile communication system is provided. When a new call is requested in a situation where it cannot be admitted, a call being serviced with a lower service level than the new call is held for admission of the new call. If the held service can be resumed under some circumstances, it is resumed.

Abstract: There is provided a data transmitting/receiving method in an HARQ data communication system. To transmit a physical layer information stream having a plurality of sub-blocks, each sub-block having an error correction code, a QoS (Quality of Service), and a priority if the sub-blocks has a different QoS, the encoded physical layer information stream is divided into a plurality of slots. The slot data are sequentially transmitted to a receiver in predetermined time intervals. If an HARQ (Hybrid Automatic Repeat Request) message for the initial slot data is received from the receiver, indicating that at least one of the sub-block in the initial slot data has a reception error and the other sub-blocks are good in reception, slot data with a sub-block having an error repeated within the number of the sub-blocks is retransmitted after transmission of initial slot data.

Abstract: A method of designating a channel to be dedicated between a base station and a mobile station in a CDMA communication system. The base station generates designation information including a common channel designation indicator, the address of a common power control channel, transmission rate, and action time and transmits a message with the designation information to the mobile station. Then, the mobile station receives the message with the designation information and transmits a response message for the received message to the base station on a designated channel indicated by the designated channel indicator with transmission power set by the common power control channel at the data rate at the action time.

Abstract: The present invention relates to a method for performing a ranging operation according to the priority order in a mobile communication system using a BWA (Broadcast Wireless Access) scheme. The method according to the invention for performing a range operation by a subscriber terminal in a mobile communication system using the BWA (Broadcast Wireless Access) scheme comprises steps of: receiving backoff domains having the start and end values of the backoff corresponding to each ranging operation, the backoff domains being determined from a base station according to the priority order of the ranging operations between the base station and subscriber terminals; performing a ranging operation and, if it is determined that the step of performing the ranging operation fails, selecting backoff domains among the received backoff domains according to the priority order of the performed ranging operations; and, re-performing the ranging operation according to the selected backoff domains.