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 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: 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 generates uplink fast feedback information to be transmitted, and outputs codewords designed such that a minimum Hamming distance between the codewords is maximized, according to the uplink fast feedback information. A non-coherent modulator performs orthogonal modulation on transmission symbols corresponding to the codewords and allocates the orthogonal-modulated transmission symbols to subcarrier cluster. An inverse fast Fourier transform (IFFT) block performs IFFT on a transmission signal having the subcarrier cluster and transmits the IFFT-processed transmission signal.

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 and apparatus for efficiently allocating subcarriers for data and/or a control signal requiring frequency diversity within the same symbol and for data or a control signal which needs to be transmitted in a frequency band with successive subcarriers, so as to transmit the signals simultaneously, satisfying the different requirements of frequency diversity and successive subcarrier allocation. Therefore, signal interference is reduced for a data signal having a frequency diversity gain and requiring a high data rate or a signal interfered by other signals.

Abstract: A method of allocating sub-channel signal interleaving patterns to BSs forming a wireless communication system that divides a frequency band into a plurality of sub-carriers and including a plurality of sub-channels, which are a set of predetermined adjacent sub-carriers. The method includes: creating a basic orthogonal sequence having a length identical to a number of the sub-carriers forming the sub-channel; creating a plurality of sequences having a same length as the basic orthogonal sequence by cyclic-shifting the basic orthogonal sequence a predetermined number of times or performing a modulo operation based on a number of the sub-carriers forming the sub-channel, after adding a predetermined offset to the cyclic-shifted basic orthogonal sequence; selecting a predetermined number of sequences corresponding to a number of the BSs from among the plurality of sequences; and allocating the selected sequences as the sub-channel signal interleaving patterns for the BSs.

Abstract: A method and apparatus for allocating subcarriers in a broadband wireless communication system using multiple carriers are provided. In the wireless communication system where the total available frequency band is divided into a plurality of subcarriers and subchannels each are formed with a predetermined number of subcarriers, the subcarriers are grouped into subcarrier groups, subcarriers are selected from the subcarrier groups according to predetermined sequences, and the selected subcarriers are allocated as a subchannel to a cell in a predetermined time period.

Abstract: A method for allocating a subchannel in a transmitter of an Orthogonal Frequency Division Multiple Access (OFDMA) cellular communication system in which an entire frequency band includes a plurality of bands, each of the bands includes a plurality of bins, and each of the bins includes a plurality of subcarriers. The method includes dividing a predetermined time interval into an Adaptive Modulation and Coding (AMC) subchannel time interval and a diversity subchannel time interval; selecting any one of the plurality of bands in the AMC subchannel time interval; selecting a predetermined number of bins among the plurality of bins in the selected band; and allocating the selected bins to the AMC subchannel.

Abstract: An apparatus and a method are provided for reducing a peak-to-average power ratio of a forward link signal in a code division multiple access (CDMA) communication system. The apparatus and method include a power control object determination unit for determining a power control object by detecting a peak signal having a highest power for a predetermined period of time from among input signals including a plurality of sub-peak signals, a power correction signal generation unit for outputting at least one correction waveform in order to correct an input signal determined to be the power control object, and a power correction unit for outputting an input signal to which at least one correction waveform is applied.