Abstract: A decoding method in a concatenated low-density generator matrix (LDGM) code-based transmission system for detecting a signal using a parity check matrix including a systematic bit part mapped to systematic bits and a parity check part mapped to parity bits. The decoding method includes generating an outer code parity check matrix with a predetermined size using a pseudorandom algorithm; generating an inner code parity check matrix using the outer code parity check matrix; and decoding a received signal using the inner code parity check matrix.

Abstract: Disclosed is a method and system for synchronizing base stations in a communication system. A mobile station receives reference base station information and base station group information, selects a synchronization correction-requiring base station from among a plurality of base stations included in a base station group corresponding to the base station group information, detects a timing offset based on reference signals received from the reference base station and synchronization correction-requiring base station, and transmits the timing offset to the synchronization correction-requiring base station so as to enable the synchronization correction-requiring base station to correct synchronization, thereby synchronizing the base stations in consideration of a real channel environment.

Abstract: An apparatus is provided for detecting a signal in a communication system using a Multiple Input Multiple Output (MIMO) scheme. The signal detection apparatus includes a detector for generating second matrixes by extending a first matrix composed of channel response vectors, generating specific matrixes by decomposing the second matrixes, generating a lattice point of vectors constituting the second matrixes, estimating a signal using the generated specific matrixes and lattice point, and detecting the estimated signal as a received signal if the estimated signal has a value within a predetermined allowable range.

Abstract: Disclosed is a method for efficiently allocating resources in a multi-cell communication system. The method includes feeding back, by a mobile station to a base station, Modulation and Coding Scheme (MCSs) corresponding to loading factors; calculating, by the base station, efficient data rates corresponding to the MCSs fedback from the mobile station; allocating, by the base station, a loading factor according to the MCSs to the mobile station; and allocating resources to the mobile station according to the loading factor.

Abstract: A transmission method based on a Hybrid Automatic Repeat Request (HARQ) scheme for in a communication system. A codeword is generated using a Low Density Parity Check (LDPC) code. Parity bits of the codeword are classified on a basis of a transmission priority. Parity bits with an identical transmission priority are grouped. An information bit group of the codeword and parity bit groups with the identical transmission priority are shuffled in a predefined pattern. A packet is generated from the shuffled information bit group and the shuffled parity bit groups based on the transmission priority. The generated packet is retransmitted in response to a retransmission request. The transmission method can obtain the effect of channel interleaving by setting a transmission priority according to importance of puncturing target blocks, shuffling blocks with the same priority, and shuffling and transmitting bits configuring each block.

Abstract: The present invention relates to a mobile communication system, and more particularly, to a method of allocating a Walsh code resource. The present invention includes determining an available maximum data rate by comparing a channel information value of a forward link with a first threshold value, determining a data rate based on a quantity of data to be transmitted, terminating to allocate the walsh codes or determining a number of the walsh codes to be requested for the data according to a comparison between the data rates, and determining a number of walsh codes for other terminals by checking a number of remaining walsh codes excluding the number of the requested walsh codes from available walsh codes.

Abstract: Disclosed is a method for transmitting an uplink signal by a mobile station in a mobile communication system using an OFDMA scheme. The method includes estimating a downlink channel status by using a signal received from a base station; determining a precoding matrix by using the estimated downlink channel status; and transmitting a signal obtained by multiplying an uplink signal to be transmitted by the precoding matrix to the base station.

Abstract: Provided is a method for puncturing a Low Density Parity Check (LDPC) code that is expressed in a factor graph configured by a bit node and a check node connected to an edge and is decoded by a parity check matrix with an information region and a parity region. A mother code with a code rate is generated. Bit nodes configuring the parity region are grouped in a block unit. A transmission code rate and the number of bits to be punctured in the mother code according to the transmission code rate are set. A puncturing process in either the block unit or a bit unit or both is performed according to the transmission code rate. All codes with required code rates can be obtained. The LDPC code puncturing method can be flexibly applied to Hybrid Automatic Repeat Request (H-ARQ) and Incremental Redundancy (IR) systems.

Abstract: Provided are a system and a method for transmitting/receiving data in a communication system. The method includes calculating a processing matrix of a transmission unit for transmitting data, a processing matrix of a reception unit for receiving the data, a channel matrix formed by a plurality of transmission antennas and a plurality of reception antennas, and a parameter of the transmission data, when the data to be transmitted to the plurality of reception antennas via the plurality of transmission antennas is generated; determining a minimum value of a Minimum Mean Square Error (MMSE) according to the calculated matrixes and parameter; and transmitting/receiving the data using an MMSE multiplexing scheme based on the determined minimum MMSE value.

Abstract: A method for generating a parity check matrix of a Low Density Parity Check (LDPC) code. A base matrix is generated in which elements with a value of 1 are arranged at predefined distances. The elements with the value of 1 in the base matrix are replaced with predefined sub-matrices. The method can improve the performance of the LDPC code by implementing the parity check matrix in which the number of 4-cycles or 6-cycles adversely affecting the LDPC code performance is minimized.

Abstract: Disclosed are an apparatus and a method for determining a transmit/receive antenna in a Multiple Input Multiple Output (MIMO) communication system. At least one sub-channel matrix including transmit antenna information and receive antenna information is generated. From the at least one sub-channel matrix, a sub-channel matrix having a maximum value Frobenius norm is determined. The transmit and receive antenna information are then extracted from the determined sub-channel matrix.

Abstract: A system and method are provided for controlling a data rate in a communication system. A transmitter sets threshold values for classifying Modulation and Coding Scheme (MCS) levels. When receiving information about an MCS level desired to be used in the receiver, the transmitter sets an MCS level to be actually used in the receiver and transmits information about the set MCS level to the receiver. When detecting that the information is to be transmitted to the transmitter, the receiver computes instantaneous link capacity using a channel estimation result, sets an MCS level mapped to the instantaneous link capacity, and transmits information about the set MCS level to the transmitter. The receiver receives the information about the MCS level to be actually used from the transmitter.

Abstract: Provided is a two-dimensional equalization method in a receiver of a communication system using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme. The receiver sets as a first value a value of a 1-tap frequency domain equalizer (FEQ) corresponding to a sub-channel allocated to the receiver , and sets as a second value a value of a 1-tap FEQ corresponding to sub-channels other than the allocated sub-channel. Upon receipt of a signal, the receiver performs Fast Fourier Transform (FFT) on the received signal, and equalizes the FFT-processed signal according to the values of the 1-tap FEQs.

Abstract: Detection of a signal in a receiver of a MIMO communication system includes a transmitter for signals transmission via K antennas and a receiver for receiving the signals via L reception antennas, such that L is greater than or equal to K and the system has a K×L-dimensional channel matrix, by converting the channel matrix into a plurality of matrixes having an upper triangle structure; dividing each of the matrixes into at least two sub-matrixes having a dimension lower than that of the channel matrix; detecting transmission symbols from corresponding antennas through decoding of a) lowest sub-matrix signal received which sub-matrix is constituted of components having only the channel characteristics of two antennas among the two sub-matrixes; and b) an upper sub-matrix signal using the transmission symbols; and outputting all of the detected transmission symbols, if transmission symbols by a highest sub-matrix among at least two sub-matrixes are detected.

Abstract: Disclosed is a method for generating a frame in an Orthogonal Frequency Division Multiple Access communication system. The method includes generating a frame having a global information zone and a local information zone, wherein the global information zone includes information that is necessary to be received commonly in all of user terminals; and the local information zone includes user terminal-by-user terminal or service-by-service traffic that is unnecessary to be received commonly in all of the user terminals.

Abstract: A method is provided for recognizing the frequency bandwidth of a base station in a mobile communication system with frequency bandwidth scalability where the transmission frequency bands of base stations and mobile stations having different frequency bandwidths are overlaid with one another. The base stations transmit to a mobile station first information, including information about their frequency bandwidths at the same frequency position over a minimum frequency bandwidth with the same center frequency. The mobile station recognizes the presence of the base stations by comparing the first information from the base stations and detects the frequency bandwidth information in the first information.

Abstract: Disclosed is a cellular-based wireless communication system, and more particularly a method for allocating resources for data transmission in a cellular-based wireless communication system employing a multicarrier scheme. Frequency resources are divided into time slots defined by one frame and the divided time slots are allocated to an uplink and the downlink. During a predetermined time period, the frequency resources are allocated as resources for transmitting sync preambles. During a next predetermined time period, the frequency resources are allocated in such a manner that the frequency resources for sectors are successively and repeatedly used as resources for transmitting broadcasting messages on a sector-by-sector basis. In the remaining time slots, except the time slots for transmitting the preambles and the broadcasting messages, the frequency resources are allocated as resources for transmitting channel estimation midambles for dynamic channel allocation.

Abstract: A transmission apparatus and method for a communication system based on Orthogonal Frequency Division Multiplexing-Code Division Multiplexing (OFDM-CDM). A frequency spreader multiplies symbols to be transmitted by a frequency spreading factor and outputs frequency spread symbols whose number corresponds to the frequency spreading factor. Buffers whose number corresponds to the frequency spreading factor temporarily store the frequency spread symbols in a unit of a predefined number of symbols. A time spreader multiplies parallel frequency spread symbols from the buffers by a time spreading factor and outputs frequency-time spread symbols. An Inverse Fast Fourier Transform (IFFT) processor performs IFFT on the frequency-time spread symbols, and outputs an OFDM symbol. A Guard Interval (GI) inserter inserts a GI into a signal output from the IFFT processor and transmits the signal.

Abstract: Provided are a spatial multiplexing apparatus and method in a Multiple Input Multiple Output (MIMO) system. The spatial multiplexing detection method includes estimating channels of a received signal, and sorting the estimated channels in descending order according to a scheme; generating a subsystem of a minimum unit by nulling an arbitrary channel among the sorted channels; performing a modified maximum likelihood (MML) in the subsystem of the minimum unit to calculate a number of transmission signal vectors; and calculating Euclidean distances of the number of the transmission signal vectors, and selecting a transmission signal vector having a minimum Euclidean distance. Accordingly, the receiver exhibits a performance level similar to a Maximum Likelihood (ML) and can obtain the complexity similar to successive interference cancellation (SIC).

Abstract: Disclosed is a signal transmitting and receiving method and system in a mobile communication system provided with a plurality of antennas. The signal transmitting method in the mobile communication system that transmits a signal through a plurality of antennas includes separating by layers and primarily encoding input data for an independent signal generation interleaving in space and time the primarily encoded data of the respective layers, receiving and secondarily encoding the interleaved data, and transmitting the secondarily encoded data through the plurality of antennas.