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: An apparatus and a method for scheduling packets in a wireless communication system. The method includes the steps of dividing a transmission deadline of the packets for a destination into a first deadline, which is an end point of the transmission deadline, and a second deadline, which is allocated before the first deadline in consideration of a transmission channel state and a quality of service (QoS) of the packets, scheduling and transmitting the packets according to transmission priorities thereof, which are determined by a predetermined scheme, before the second deadline, and scheduling and transmitting the packets according to an approaching order of the packets with respect to the first deadline, if the packets have passed through the second deadline.

Abstract: A system for performing network re-entry upon handover of a mobile subscriber station (MSS) to a target base station (BS). Upon detecting handover of the MSS, the target BS detects network re-entry information necessary for network re-entry of the MSS from the serving BS, and transmits, to the MSS, the detected network re-entry information, information on an acknowledge (ACK) channel through which the MSS will respond that it has received the network re-entry information upon receipt of the network re-entry information, and ACK request information requesting the MSS to respond whether it has received the network re-entry information. The MSS receives the ACK channel information, and thereafter receives, from the target BS, the network re-entry information and the ACK request information, and a response transmits to the target BS which indicates that it has received the network re-entry information, through the ACK channel in response to the ACK request information.

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: In a Broadband Wireless Access (BWA) communication system having at least two FAs, a base station (BS) requests a subscriber station (SS) to change its FA from the first FA to the second FA, upon detecting a need to change an FA of the SS from the first FA to the second FA while communicating with the SS. The SS informs the BS that it will change its FA from the first FA to the second FA in response to the FA change request, and then changes its FA from the first FA to the second FA. After changing the FA, the SS communicates with the BS through the second FA.

Abstract: A method for performing a handover by a subscriber station (SS) in a broadband wireless communication system including a serving base station (BS) communicating with the SS, and at least one neighbor BS neighboring the serving BS. The SS receives downlink signals from the serving BS and the neighbor BS; measures an arrival time difference between the downlink signal received from the serving BS and the downlink signal received from the neighbor BS; and transmits the measured arrival time difference to the serving BS.

Abstract: An apparatus and method for controlling operation states of a medium access control layer by a mobile subscriber station (MSS) in a broadband wireless access communication system. The method includes: state-transitioning into a sleep state or an idle state when there is no data transmitted between a base station and the MSS during a predetermined first time interval in an awake state; and performing a location change in the idle state when the mobile subscriber station moves from a first paging zone to a second paging zone, and state-transiting into the awake state when the mobile subscriber station in the idle state detects a paging to the mobile subscriber station. The method minimizes power consumption and maximizes efficiency in use of radio resources.

Abstract: A mobile communication system using an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) scheme. The method for assigning ranging codes in the OFDM/OFDMA communication system includes classifying rangings between a base station and a mobile subscriber station (MSS) of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging. A first number of ranging codes used for the rangings are created and a second number of ranging codes selected from the first number of ranging codes are assigned as handover ranging codes used for the handover ranging.

Abstract: A method for transmitting common control information from a base station to a plurality of subscriber stations in a wireless communication. The common control information includes first information transmitted in common to all of the subscriber stations and second information separately transmitted to the subscriber stations according to channel states of the subscriber stations. The first information is transmitted using an MCS (Modulation and Coding Scheme) level having a modulation scheme with a lowest order and a coding scheme with a lowest coding rate among all MCS levels available in the base station. The second information is transmitted using MCS levels that are adjusted by a predetermined level against MCS levels corresponding to channel states of the subscriber stations.

Abstract: Disclosed is a method for controlling an operational state of at least one subscriber stations in an OFDM/OFDMA communication system having ranging slots and ranging codes to be used for rangings.

Abstract: A method for transmitting a ranging code from a base station to subscriber stations to prevent collision during a random access by the subscriber stations in an Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access (OFDM/OFDMA) communication system. The method includes allocating connection identifiers (CIDs) for identifying the subscriber stations, allocating group IDs to the CIDs to divide the subscriber stations into a predetermine number of groups, and allocating ranging codes for distinguishing subscriber stations in a group corresponding to each of the allocated group IDs.

Abstract: An method and apparatus for transmitting ranging information from at least one base station to subscriber stations and generating a ranging signal by the subscriber station using received ranging information in a Broadband Wireless Access (BWA) communication system including a plurality of neighbor cells and a plurality of the subscriber stations located in each cell region. A first code generator generates a first code using different first code information received from the base stations in the neighbor cells allocated the first code information. A second code generator generates a second code using second code information received by each of the subscriber stations existing in cell regions of the neighbor cells. A ranging signal generator generates a new ranging signal by combining the first code with the second code.

Abstract: Disclosed is an echo path delay estimating apparatus and method for estimating the echo path delay using decimators and an adaptive filter, so that a short computation time is used by the echo canceller.