Abstract: An apparatus and a method for simultaneously supporting Multiple-Input Multiple-Output (MIMO) and beamforming in a wireless communication system are provided. In the method, two data streams are mapped to each of all of 2N transmission antennas; the two data streams are multiplied by different Cyclic Delay Diversity (CDD) phase sequences; the two data streams multiplied by the different CDD phase sequences for each transmission antenna are added; and the added data stream is multiplied by a beamforming coefficient and transmitted for each transmission antenna.

Abstract: Disclosed are an apparatus and a method for transmitting uplink control information in an OFDMA communication system. The method, in which the uplink control information is transmitted using an ACK channel in the OFDMA communication system, includes the steps of receiving data bits of the uplink control information, outputting transmit symbols of sub-carriers by performing orthogonal modulation with respect to symbols for codewords of the received data bits, and inverse fast fourier transforming and transmitting a transmit signal including bundles of sub-carriers allocated the modulated transmit symbols.

Abstract: A method for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme is provided. A mobile station (MS) selects a target anchor base station (BS) with which the MS desires to communicate through a fast feedback channel, and transmits a codeword allocated to the selected target anchor BS to a current anchor BS. Upon receiving the codeword, transmitting to the MS, by the anchor BS, fast feedback channel allocation information for the selected BS corresponding to the received codeword. The MS switches to a new anchor BS corresponding to the fast feedback channel allocation information.

Abstract: A calibration apparatus and method for supporting a Relay Station (RS) in a multiple antenna communication system are provided. The calibration method in the multiple antenna communication system which supports the RS includes, when a modem stage sends a downlink calibration signal, receiving, at a calibrator, the downlink calibration signal and estimating a downlink path channel, when the calibrator sends an uplink calibration signal, receiving, at the modem stage, the uplink calibration signal and estimating an uplink path channel, determining, at the modem stage, calibration coefficients per path not to generate a phase and amplitude difference with respect to the estimated uplink path channel and the estimated downlink path channel, and applying the calibration coefficients per path to corresponding antennas respectively.

Abstract: An apparatus is provided for transmitting uplink fast feedback information in a wireless communication system. In the apparatus, a channel encoder generates uplink fast feedback information to transmit, and outputs 3-bit codewords being set according to the fast feedback information. A noncoherent modulator modulates transmission symbols corresponding to the codewords using a noncoherent modulation scheme, and allocates the modulated transmission symbols to each of subcarrier bundles. An inverse fast Fourier transform (IFFT) unit IFFT-processes a transmission signal comprised of the subcarrier bundles before transmission.

Abstract: An apparatus and method for eliminating interference in a base station (BS) of a communication system. A first BS receives a first reception signal from a first mobile station located in a cell of the first base station. A second base station being adjacent to the first base station delivers decoding information of a second reception signal to the first base station, the second reception signal received from a second mobile station located in a cell of the second base station. The first BS determines whether an error exists on the second reception signal, based on the decoding information and re-generates an interference signal using the decoding information of the second reception signal when no error exists in the second reception signal, and performing interference elimination on the first reception signal using the re-generated interference signal.

Abstract: A method and apparatus for transmitting uplink acknowledge information (ACK) in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme. The method includes receiving a data bit for the uplink ACK; outputting codewords corresponding to the data bit; performing quadrature phase shift keying (QPSK) modulation on symbols for ACK vector indexes corresponding to the codewords for the received data bit; performing inverse fast Fourier transform (IFFT) on a transmission signal having subcarrier clusters to which the modulated transmission symbols are allocated; and transmitting the IFFT-processed transmission signal.

Abstract: An apparatus and method for transmitting uplink fast feedback information using a fast feedback channel in an orthogonal frequency division multiple access (OFDMA) communication system. A channel encoder selects information data for uplink fast feedback information, and determines a codeword from a pre-determined codeword set corresponding to the selected information data. A non-coherent modulator chooses transmission symbols by performing orthogonal modulation according to the determined codeword based on a predetermined modulation pattern, and maps the chosen symbols into sub-carriers. An inverse fast Fourier transform (IFFT) block performs an inverse fast Fourier transform (IFFT) on the mapped symbols and transmits the IFFT processed mapped symbols.

Abstract: An apparatus and a method for estimating a channel using sliding windows in a broadband wireless communication system are provided. The apparatus includes an estimator, a first calculator, a second calculator, and a third calculator. The estimator estimates a speed of travel. The first calculator calculates a time correlation values using the estimated speed. The second calculator calculates weight factors using the time correlation values. The third calculator calculates a channel estimation value by multiplying corresponding pilot symbols by the weight factors and equalizing the pilot symbols.

Abstract: An apparatus and a method for interference cancellation in a broadband wireless communication system are provided. A receiving apparatus includes an estimator, a channel compensator, and a demodulator. The estimator estimates channels of a desired signal and at least one interference signal, estimates noise, calculates a mean interference power of each interference signal, and calculates a mean noise power. The channel compensator channel-compensates burst data. The demodulator calculates a noise variance value by adding the mean noise power to the at least one mean interference power and creates Log Likelihood Ratio (LLR) by demodulating the channel-compensated data.

Abstract: A method and apparatus for estimating noise in a signal reception apparatus of a communication system are provided. The method and apparatus include a channel estimator for estimating a channel for a signal vector received from multiple cells, and a noise estimator for estimating noise using the received signal vector, a number of the cells, a number of pilot subcarriers used for the channel estimation and pilot patterns used in the cells. As provided, the noise estimation method and apparatus improve decoding performance which improves cell capacity in a communication system.

Abstract: A Channel estimating apparatus and method for use in a broadband wireless communication system are provided. The receiving method includes determining a control unit for a channel estimation using burst allocation information of selected sectors; extracting pilot symbols from received data based on the control unit; and acquiring a channel estimate value for each transmission unit by performing a Joint Channel Estimation (JCE) with the extracted pilot symbols that are based on the control unit.

Abstract: An interference canceling apparatus and method in a broadband wireless communication system is provided. The method includes deriving a first channel estimate value of a desired signal and a first interference channel estimate value of an interference signal by using burst allocation information of selected sectors or cells; deriving a first noise estimate value using the first channel estimate values and the first interference channel estimate value; detecting an interference signal interfering the desired signal by using the first interference channel estimate value and the noise estimate value; deriving burst allocation information of the detected interference signal and the desired signal; and deriving a second channel estimate value of the desired signal and a second interference channel estimate value of the interference signal using the derived burst allocation information.

Abstract: An apparatus is provided for transmitting uplink fast feedback information in a wireless communication system. In the apparatus, a channel encoder generates uplink fast feedback information to transmit, and outputs 3-bit codewords being set according to the fast feedback information. A noncoherent modulator modulates transmission symbols corresponding to the codewords using a noncoherent modulation scheme, and allocates the modulated transmission symbols to each of subcarrier bundles. An inverse fast Fourier transform (IFFT) unit IFFT-processes a transmission signal comprised of the subcarrier bundles before transmission.

Abstract: A method for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme is provided. A mobile station (MS) selects a target anchor base station (BS) with which the MS desires to communicate through a fast feedback channel, and transmits a codeword allocated to the selected target anchor BS to a current anchor BS. Upon receiving the codeword, transmitting to the MS, by the anchor BS, fast feedback channel allocation information for the selected BS corresponding to the received codeword. The MS switches to a new anchor BS corresponding to the fast feedback channel allocation information.

Abstract: An apparatus and method for processing received signals in a handover of a MS in a BWA communication system including a plurality of BSs capable of providing a service to the MS. According to the method, the MS receives signals of different BSs and detects preambles for each BS from the received signals. Further, the MS measures channel quality information corresponding to each of the detected preambles and compares the measured channel quality information with a preset threshold value. Further, the MS processes the signals received from the different BSs based on a result obtained by comparing the measured channel quality information with the preset threshold value.

Abstract: Disclosed is a method for supporting a serving BS currently providing an MS with a communication service to perform handover in a broadband wireless access communication system which includes the MS, the serving BS and a target BS to which handover of the MS is directed. In such a method, the serving BS allocates the same sub-channel as that allocated to the MS in a specific time period by the target BS in the same time period, and information about the allocated sub-channel is transmitted to the MS.

Abstract: A method and apparatus for transmitting uplink acknowledge information (ACK) in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme. The method includes receiving a data bit for the uplink ACK; outputting codewords corresponding to the data bit; performing quadrature phase shift keying (QPSK) modulation on symbols for ACK vector indexes corresponding to the codewords for the received data bit; performing inverse fast Fourier transform (IFFT) on a transmission signal having subcarrier clusters to which the modulated transmission symbols are allocated; and transmitting the IFFT-processed transmission signal.

Abstract: A method for setting a guard interval for distinguishing a transition from a downlink period to an uplink period in a mobile communication system employing a time division duplexing (TDD) scheme, the mobile communication system including a plurality of base stations. The method includes the steps of, simultaneously transmitting by each of the base stations downlink signals from transmission antennas at a first time point based on a processing delay time for a signal to be transmitted; simultaneously receiving by each of the base stations an uplink signal at reception antennas at a second time point; and setting a time interval from the first time point to the second time point as a guard interval for distinguishing a transition from an uplink period to a downlink period.

Abstract: Disclosed is a method for supporting a handover in a broadband wireless access communication system which includes a mobile subscriber station, a serving base station currently providing service to the mobile subscriber station, and a plurality of adjacent base stations different from the serving base station, in which each of the base stations includes cells using subchannel bands different from each other, the method including establishing a set of base stations which currently provide wireless channels for data transmission/reception to the mobile subscriber station; classifying, by each base station, entire subchannels into a plurality of sets of subchannels; and allocating each of the sets of subchannels obtained by the classification to a PUSC (Partial Usage of Subchannels) subchannel area of each sector, wherein, every base stations included in an active set select an equal number of PUSC subchannels from among a PUSC subchannel area allocated to each of the base stations and allocate the selected PUSC