Abstract: A transmitter and a receiver are disclosed herein that support transmit antenna diversity using space-time block coding in a wireless communication system. The transmitter produces symbol combinations containing, as their elements, input symbols, the inversions and conjugates of the symbols, and symbols obtained by rotating the phases of the symbols once, forms a matrix having symbols in at least two columns orthogonal to each other with the symbol combinations, and transmits the matrix. The receiver detects symbols that minimize maximum likelihood (ML) decoding metrics over all possible symbols using channel gains from transmit antennas to a receive antenna. Also, the receiver selects candidate symbols among all possible symbols according to the characteristics of transmitted modulation symbols and detects symbols that minimize the ML decoding metrics.

Abstract: A method for providing a service in a communication system is provided. A Base Station (BS) supporting a plurality of communication service modes allocates communication resources for each of the plurality of communication service modes according to a ratio determined in accordance with a communication service mode preferred by a terminal. The BS transmits a combination of resources allocated for each of the plurality of communication service modes to the terminal. The communication service mode preferred by the terminal is determined using at least one of channel condition of the terminal, moving velocity, preferred communication mode, required performance, billing system, and user preference.

Abstract: A method for transmitting and receiving data in a communication system. The method generates a frame for mapping each of multiple communication service modes of a base station providing the multiple communication service modes to a user terminal, in units of subframes each having a time interval and a frequency band. The method includes estimating a communication service mode supporting an optimal service among the multiple communication service modes provided by the base station supporting the multiple communication service modes, and sending to the base station a random access message for access to the base station over a shared channel.

Abstract: Disclosed is a method for transmitting a signal in a communication system supporting multiple communication service modes. The base station includes at least one preamble generator for generating a preamble to which a sequence and a cell IDentifier (ID) of the base station are allocated, the sequence being one-to-one mapped to one communication service mode supportable by the base station. By the method, in mobile communication systems after the 3G communication system, it is possible to support multiple communication service modes optimized for multiple communication environments in a single communication system and to provide each mobile station with an optimum communication service mode for a specific communication environment of the mobile station.

Abstract: Provided is a parallel interleaving method and apparatus. The parallel interleaving method includes dividing input information bits into a predetermined number of sub-blocks and interleaving the information bits divided into the sub-blocks according to a predetermined first interleaving rule.

Abstract: A method and an apparatus for transmitting a signal in a communication system are provided. An information vector is encoded according to a Low Density Parity Check (LDPC) encoding scheme, thereby generating an LDPC codeword. Minimum surviving check nodes are reserved for recovery of punctured nodes in the LDPC codeword. A check node is selected having a smallest cost function from among unreserved check nodes. A variable node is selected being unpunctured and having a smallest cost function from among variable nodes connected to the selected check node. The selected variable node is punctured when the selected variable node is not connected to the reserved check node. A stopping set check is performed when the selected variable node is connected to the reserved check node. The variable node is punctured when the stopping set check has been successfully performed. The check node is selected until there remains no variable node to be punctured and puncturing the variable node.

Abstract: Provided is a transmitter apparatus in a MIMO wireless communication system. The transmitter apparatus includes a controller and a space-time encoder. The controller generates a space-time encoding code according to a multiplexing order, the number of transmitter antennas, and the number of receiver antennas. The space-time encoder space-time-encodes a TX signal using the generated space-time-encoding code.

Abstract: An apparatus uses transmission antenna diversity to compensate for fading. An encoder according to a first embodiment forms 4 combinations each including 3 symbols so that 4 input symbols should be transmitted only once at each antenna and each time interval, and delivers the combinations to the 3 transmission antennas for 4 time intervals, and two or more symbols selected from the 4 input symbols are phase-rotated by predetermined phase values before being transmitted via the transmission antennas. An encoder according to a second embodiment forms 3 combinations each including 3 symbols so that 3 input symbols should be transmitted only once at each antenna and each time interval, and delivers the combinations to the 3 transmission antennas for 3 time intervals, and two or more symbols selected from the 3 input symbols are phase-rotated by predetermined phase values before being transmitted via the transmission antennas.

Abstract: A mobile communication system includes at least three transmission antennas of first to third transmission antennas, and uses an overlapped antenna scheme for grouping the first and second transmission antennas into a first transmission antenna group and grouping the second and third transmission antennas into a second transmission antenna group. First and second modulators modulate L information bit streams to be transmitted through the first transmission antenna group and output first and second modulation symbol streams. Third and fourth modulators modulate L other information bit streams to be transmitted through the second transmission antenna group and output third and fourth symbol streams. First to fourth puncturers puncture at least one modulation symbol in a predetermined position among the first to fourth modulation symbol streams.

Abstract: A method for performing ranging by a mobile station in a communication system. The method includes transmitting a ranging sequence to a relay station; receiving an added signal of a reference sequence of the relay station and the ranging sequence, from the relay station; performing a correlation operation on each of the ranging sequence and the reference sequence in the added signal; estimating a time difference between the ranging sequence and the reference sequence depending on the correlation operation; and transmitting the signal to the relay station taking the time difference into account.

Abstract: Provided are a relaying method and system in a communication system having a BS, a MS for communicating with the BS, and an RS for relaying signals between the BS and the MS, in which the RS receives a first pilot sequence from the BS, replaces the first pilot sequence with a second pilot sequence, and transmits the second pilot sequence to the MS. Here, a partial cross correlation between the first and second pilot sequences is always ‘0’.

Abstract: A relaying method and system in a communication system having a Base Station (BS), a Mobile Station (MS) for communicating with the BS, and a Relay Station (RS) for relaying signals between the BS and the MS are provided. In the relaying method and system, the BS generates a BS pilot sequence and transmits the generated BS pilot sequence to the RS. wherein a partial cross correlation between the BS pilot sequence and an RS pilot sequence, being the BS pilot sequence relayed by the RS is always ‘0’. Accordingly, system capacity is more efficiently utilized.

Abstract: A method and system for selecting an RS in an MS in a communication system are provided, in which the MS measures channel qualities between the MS and at least two RSs, and selects an RS for relaying signals between the MS and a BS from among the at least two RSs according to the channel quality measurements.

Abstract: A mobile communication system having M transmission antennas for receiving P information bit streams and encoding the received information bit streams with a space-time trellis code (STTC) according to an optimal generator polynomial; modulating the encoded P information bit streams in a predetermined modulation scheme and outputting modulation symbol streams; and puncturing at least one modulation symbol in a predetermined position from each of the M modulation symbol streams, and transmitting the punctured modulation symbol streams through the M transmission antennas, thereby increasing a data rate while maintaining maximum diversity gain.

Abstract: An apparatus and method for removing interference in a transmitting end of a multi-antenna system is provided. The method includes decomposing a channel matrix comprising channel coefficients for a plurality of terminals, calculating a value proportional to an interference signal for each of antennas, and calculating a sum of a transmission signal and the calculated value for each terminal and multiplying the calculated sum by the decomposed channel matrix. Accordingly, channel capacity can be improved by optimizing a data transfer rate and transmission power for each terminal.

Abstract: An apparatus and method for feeding back Channel Quality Information (CQI) in a wireless communication system are provided. Total channels are grouped into certain number of groups according to downlink channel estimates. Group indexes are determined for the channels. Feedback information is generated using the group indexes of the channels and representative values of the groups. Then, the generated feedback information can be transmitted.

Abstract: A multiple access method in a wireless communication system using a plurality of multiple access techniques is provided. When a call is established with a wireless terminal, the terminal transmits a duplexing mode determination factor to the base station to set a time or frequency division duplexing mode for reverse transmission and determine access and hopping modes according to each of the division duplexing modes, and establishes forward and reverse channels according to the set time or frequency division duplexing mode for reverse transmission to communicate with the base station. The base station receives the duplexing mode determination factor from the terminal, sets a time or frequency division duplexing mode for reverse transmission and sets a time division duplexing mode for forward transmission based on the received factor, and determines frequency hopping and multiple access modes to communicate with the terminal according to the determined frequency and multiple access modes.

Abstract: A mobile communication system, a transmitter includes a first transmission antenna and a second transmission antenna, and the first and second transmission antennas transmit signals through at least one odd carrier and at least one even carrier. The transmitter determines a first symbol and a second symbol to be used for initial channel estimation of a receiver, encodes the first symbol and the second symbol by a preset transmit diversity scheme for a preset time, and transmits the encoded first and second symbols to the receiver through odd carriers and even carriers of the first transmission antenna and the second transmission antenna.

Abstract: A receiver for receiving complex symbols in a radio communication system, in which a symbol arranger collects signals from at least three transmitter antennas through at least one receiver antenna over four time intervals; a channel estimator estimates at least three channel gains from the three transmitter antennas to the receiver antenna; first and second decoders each compute metrics for all possible pairs of symbols using the received signals and channel gains, and detect two symbols having a minimum metric; And a P/S (Parallel to Serial) converter arranges the detected symbols in the right order. Each decoder linearly operates the received signals and channel gains, pre-detects two symbols using threshold detection, and outputs the pre-detected symbols as final symbols if the product of the product of the pre-detected symbols and a constant determined by the channel gains is a minimum.

Abstract: An apparatus using transmitting antenna diversity to combat degradation due to fading in a wireless communication system. At least two symbols of four symbols to be transmitted through four transmitting antennas are rotated by predetermined phase values. An encoder configures four combinations for four input symbols so that a sequence of four symbols can be transmitted once by each transmitting antenna during each time interval. The combinations are transferred to the four transmitting antennas during four time intervals. Before the four input symbols are transmitted to the transmitting antennas, at least two symbols selected from the four input symbols are rotated by predetermined phase values. Therefore, the maximum diversity order can be obtained, a transmission delay time can be reduced, and the effect of fast fading can be reduced.