Abstract: An apparatus and method for supporting Hybrid Automatic Repeat reQuest (HARQ) in a broadband wireless communication system are provided. A method of performing HARQ by a Mobile Station (MS) in a wireless communication system includes receiving a control message including resource allocation information, decoding the control message, if the decoding is successful, determining whether a previous control message is lost, and if the previous control message is lost, transmitting one of a null signal and a specific indicator through a response channel.

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.

Abstract: A Low Density Parity Check (LDPC) encoding apparatus and method are provided. The LDPC encoding apparatus includes a controller for determining a number of zeros b to be inserted in an input information vector when a length of the input information vector is less than a length of a use information vector of a parity-check matrix, for selecting b stopping sets Sd using the parity-check matrix, for selecting one variable node from each of the b stopping sets Sd using a selection scheme, and for determining positions corresponding to the selected variable node from each of the b stopping sets Sd as positions where zeros are to be inserted.

Abstract: A resource allocation for reducing overhead in a mobile communication system is provided. An operating method of a base station for changing a fixed resource allocation to reduce overhead in a mobile communication system includes calculating a total amount of resources allocated to a corresponding subframe in a period of a corresponding fixed allocation resource; when the total amount of the resources allocated to the corresponding subframe is greater than a threshold, temporarily canceling one or more corresponding fixed allocation resources to make the total amount of the resources allocated to the corresponding subframe less than or equal to the threshold; and reallocating the one or more canceled fixed allocation resources according to a corresponding rule.

Abstract: An apparatus and method for controlling a Hybrid Automatic Repeat reQuest (HARQ) operation in a transmitter of a wireless mobile communication system using each frame constituted by a plurality of subframes are provided. In the method for controlling an HARQ operation, indication information indicating a subframe position where transmission of a data burst starts and the number of subframes required for transmission of the data burst is transmitted to a receiver through an i-th frame. When the number of subframes does not exceed a threshold, it is determined that the data burst at the subframe position indicated by indication information of an (i+1)-th frame is retransmitted to the receiver. When the number of subframes exceeds the threshold, it is determined that the data burst at the subframe position indicated by indication information of an (i+n)-th frame, where n is a positive integer exceeding 1, is retransmitted to the receiver.

Abstract: An apparatus and method for transmitting a signal in a communication system using a Hybrid Automatic Repeat reQuest (HARQ) scheme are provided. The method includes generating a codeword vector by encoding an information vector by using a first parity check matrix of Low Density Parity Check (LDPC) codes, generating a transmission vector by processing the codeword vector, and transmitting the transmission vector. When the first parity check matrix includes a plurality of square matrix columns, each square matrix includes a size of L×L, the first parity check matrix is one of p parity check matrixes stored in the signal transmission apparatus, the p parity check matrixes support different numbers of information vector square matrix columns, and each of the numbers of information vector square matrix columns indicates the number of square matrix columns corresponding to the information vector from among the plurality of square matrix columns.

Abstract: Disclosed is an apparatus and method for transmitting/receiving a control message in a wireless communication system that is designed to reduce overhead associated with transmission/reception of the control message. To this end, a transmission apparatus generates a control message, generates a compressed control message by compressing the generated control message, based on a control message that has been lastly received by a reception apparatus from among previously transmitted control messages, selects one of the generated control message and the generated compressed control message according to whether or not the control message lastly received by the reception apparatus exists, and transmits the selected one of the generated control message and the generated compressed control message to the reception apparatus. Therefore, it is possible to reduce resources used for control message transmission, and thus increase the use efficiency of the resources.

Abstract: An apparatus and method for operating a Fractional Frequency Reuse (FFR) scheme in a broadband wireless communication system is provided. The method includes broadcasting a reference value for determining an FFR region, receiving region information determined by using the reference value from at least one Mobile Station (MS), and determining a communication band of at least one MS by using the region information received from the at least one MS.

Abstract: A system and method are disclosed for transmitting/receiving a signal in a communication system in which a first communication system and a second communication system coexist, the second communication system being evolved from the first communication system and being capable of using a control signal and a broadcast signal used in the first communication system. The method of transmitting a signal includes the steps of transmitting a first message including common control information and frame control information for the first communication system in a first frame, transmitting a second message including common control information and frame control information for the second communication system in a second frame, and signaling location information of the transmitted second message in the second frame.

Abstract: A method and apparatus for transmitting and receiving forward channel status information in a multi-carrier mobile communication system. An MS transmits to a BS forward channel status information representing an average C/I of forward signals with respect to a plurality of carriers, the maximum of the forward signal C/Is, or each of the forward signal C/Is. The forward channel status information is absolute C/I information representing a current C/I, or relative C/I information representing a difference of the current C/I from a previous C/I.

Abstract: An apparatus and a method for transmitting uplink feedback data in a broadband wireless mobile communication are provided. The method comprises dividing tiles used as a feedback channel into a preset number of groups, selecting one group among the preset number of groups using a downlink channel, selecting a number of tiles, the number of tiles being equal to a number of tiles required for feedback data transmission in the selected group, and mapping feedback data to each selected tile. Thereby, feedback information can be transmitted via a tile selected by a terminal based on a channel state without a process of allocating and reallocating an additional feedback channel, thus enhancing efficiency of uplink wireless resources.

Abstract: Disclosed is a method of transmitting common control information by a base station in a communication system including a first communication system and a second communication system different from each other. In the communication system, a frame for carrying the common control information includes an uplink sub-frame and a downlink sub-frame, each of which includes a resource allocation area for the first communication system and a resource allocation area for the second communication system. The method includes: configuring the common control information to be received by a mobile station belonging to the second communication system; and transmitting the common control information through the resource allocation area for the second communication system included in one of the uplink sub-frame and the downlink sub-frame.

Abstract: A method and system for transmitting/receiving data in a heterogeneous communication system. A terminal accesses a first controller of a first communication system supporting a first communication service to make a communication path to the first communication system. After making the communication path to the terminal, the first controller determines whether it is possible to provide the first communication service to the terminal over the first communication system. If it is not possible, the first controller transmits to an interworking unit a first request indicating that the terminal requires the first communication service over the second communication system. The interworking unit transmits a second request to a second controller of the second communication system in response to the first request, the second request indicating that the second controller provides the first communication service to the terminal.

Abstract: A method for communicating with a network by a terminal in a wireless communication system, wherein the terminal receives, from the network, signaling information representing a transmission period and a time offset for uplink transmission of a feedback information, and determines a time to transmit the feedback information based on the transmission period and the time offset. The terminal transmits the feedback information to the network based on the determined time.

Abstract: An apparatus and method support various system bandwidths in a broadband wireless communication system. A Mobile Station (MS) operation includes determining a system bandwidth through a primary preamble for frame synchronization, which a Base Station (BS) transmits. A Fast Fourier Transform (FFT) size, the number of guard subcarriers, and the number of used subcarriers corresponding to the system bandwidth are determined using a first table. An operation parameter of a modem is set according to the FFT size, the number of guard subcarriers, and the number of used subcarriers.

Abstract: Disclosed is a system and method for service interworking between heterogeneous communication systems. The service interworking system includes a first system and a second system that is evolved from the first system and can decode control and broadcast signals used in the first system. The first and second systems provide services by using frequency bands that do not overlap with each other.

Abstract: Provided is an apparatus and method for estimating an uplink frequency offset in a wireless communication system. In a receiving apparatus of a wireless communication system using a random access channel composed of two equivalent sequences, the apparatus includes a channel receiver which extracts samples corresponding to the two sequences from an input random access channel signal; a correlator which computes first and second correlation values by correlating preceding and trailing samples among the samples output from the channel receiver with a predetermined sequence; and a frequency offset estimator which estimates a frequency offset by using a ratio of the second correlation value to the first correlation value output from the correlator.

Abstract: A method is provided for controlling power in a communication system. The power control method includes allocating a first data transmission region and a second data transmission region corresponding to a first communication scheme and second communication scheme; providing a communication service to a receiver through the first data transmission region, and receiving power control information from the receiver through the second data transmission region while providing the communication service; and adjusting a level of transmission power used for providing the communication service according to the received power control information, and providing the communication service to the receiver using the adjusted transmission power.

Abstract: A method and apparatus for joint unicast using multi-user superposition coding in a wireless relay system are provided. A BS superposition-encodes first and second data messages directed to first and second MSs, respectively, scheduled at a current scheduling instant. The first and second data messages carry first and second information bit streams for the first and second MSs, respectively. The first MS has a relatively good direct link to the BS, and the second MS has a relatively bad direct link to the BS. The superposition-coded data is transmitted to the first MS and an RS connected between the BS and the first and second MSs. The RS receives the superposition-coded data from the BS, extracts the second information bit stream by decoding the superposition-coded data, and transmits a third data message carrying the second information bit stream to the first and second MSs.

Abstract: An apparatus and method for Automatic Repeat reQuest (ARQ) in a Multi Input Multi Output (MIMO) system. The method includes computing weights of erroneous packets and weights of transmitting antennas by using channel information; sorting the weights of the erroneous packets in descending order; sorting the weights of the transmitting antennas in ascending order; and assigning the transmitting antennas to the erroneous packets according to sorting results.