Abstract: An iterative detection and decoding method in a Multiple Input Multiple Output (MIMO) system includes detecting entire MIMO nodes to generate soft decision values; decoding a first soft decision value among the soft decision values; determining whether to perform an iterative detection and decoding by measuring reliability of the decoded first decoding signal; generating a soft decision value by performing a redetection of a MIMO node containing the soft decision value, when the decoded soft decision value is iteratively detected and decoded; and decoding a second soft decision value among the soft decision values.

Abstract: A method and an apparatus for pre-scheduling in a closed-loop multiple user multiple input multiple output (MU-MIMO) antenna system. A base station receives channel information representing a downlink channel condition of each mobile station from mobile stations in a cell, and determines a candidate user group for each of frequency bands included in an entire frequency band, based on the channel information, the candidate user group including mobile stations to which resources can be simultaneously allocated. The base station also instructs a mobile station included in each candidate user group to transmit a sounding signal through a corresponding frequency band. If the sounding signal is received through the corresponding frequency band, the base station performs a scheduling with regard to the mobile station included in each candidate user group.

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: For cooperative transmission in a broadband wireless communication system, an apparatus and operating method of a Base Station (BS) in a broadband wireless communication system are provided. The method includes receiving a cooperative transmission REQuest (REQ) message which includes at least one of information designating a cooperative Mobile Station (MS), a pilot pattern of the cooperative MS, a variable determining a permutation pattern, and an orthogonal code of the cooperative MS, from a control station, allocating a resource of a predefined Coordinated MultiPoint transmit/receive (CoMP) zone occupying part of a frame, to at least one cooperative MS designated by the cooperative transmission REQ message, and communicating with the at least one cooperative MS according a cooperative transmission scheme using the resource of the CoMP zone.

Abstract: Provided are an apparatus and method for canceling interference in a Broadband Wireless Access (BWA) system. The method includes estimating channel coefficient vectors of a plurality of Mobile Stations (MSs) using the same resource; computing a correlation matrix by subtracting a channel coefficient vector of a corresponding MS from a specific tone input vector within the same resource and by auto-correlating the subtracted vector; canceling interference from the data-tone input vector and the channel matrix by using the correlation matrix; and estimating a transmission symbol for each MS by performing Multiple Input Multiple Output (MIMO) detection by using the interference-cancelled input vector and the interference-cancelled channel matrix.

Abstract: An apparatus and method for generating LLRs in an MIMO communication system. In a receiver for a spatial multiplexing communication system, a determiner performs an MML decoding operation in an ascending or descending order of TX antennas to estimate a plurality of candidate TX vectors. A distance calculator calculates a Euclidean distance for each of the candidate TX vectors from the determiner. An LLR calculator calculates LLRs using the Euclidean distances from the distance calculator. Accordingly, it is possible to generate an LLR with high reliability at low complexity in an MIMO communication system.

Abstract: A method and apparatus for receiving data in a communication system is disclosed. Receiving a first signal from a transmitter, a first canceller cancels from the received first signal a second signal desired to be received from the transmitter. A second canceller detects and cancels an interference signal from the second signal-canceled first signal. A calculator calculates a Log Likelihood Ratio (LLR) of the interference signal-canceled first signal.

Abstract: A method and apparatus for multi-cell calibration in a wireless communication system supporting cooperative Multiple Input Multiple Output (MIMO) are provided. Operations of a Base Station (BS) according to the method include transmitting a first message indicating a start of multi-cell sounding calibration to a reference Mobile Station (MS); estimating an uplink channel matrix of the reference MS using pilot symbols received from the reference MS; transmitting pilot symbols for enabling the reference MS to estimate a downlink channel matrix; when receiving downlink channel information of cooperative BSs from the reference MS, transmitting second messages comprising the downlink channel information to the cooperative BSs; and determining a multi-cell calibration matrix using the uplink channel matrix and the downlink channel information received from the reference MS.

Abstract: An apparatus is operable to control power of a base station in a distributed Multiple Input Multiple Output (MIMO) wireless communication system. At least one beamforming matrix is used for processing transmission signals to terminals included in a terminal set for a multiple access is determined. Minimum power values required for satisfying a minimum transmission rate of the terminals are determined. Whether optimum power values exist is determined using the minimum power values, the beamforming matrix, and a limit transmission power of the base station. When the optimum power values exist, transmission power values for respective terminals are determined in a range meeting the limit transmission power of the base station.

Abstract: An apparatus and a method for determining an optimum integer perturbation vector of a low complexity in a multiple antenna system include a transmitter that transmits data using an optimum integer perturbation vector of a low complexity in a multiple antenna system includes a module pre-processor, a shift pre-processor, and a precoder. The modulo pre-processor adds an integer perturbation vector to a transmission signal vector. The shift pre-processor phase-shifts a pseudo inverse matrix of a channel matrix using a phase angle. The precoder precodes a transmission signal vector perturbed by the integer perturbation vector using the phase-shifted pseudo inverse matrix of the channel matrix.

Abstract: A method and apparatus enhances sounding performance for a broadband wireless communication system of a multi-cell environment. A grouping part groups a plurality of sounding sequences to a plurality of sequence groups. A first determiner determines a correlation between the sequence groups. A second determiner determines a least interference relation between sectors in a cluster. An allocator allocates the sequence groups to the sectors based on the correlation between the sequence groups and the least interference relation between the sectors.

Abstract: In a communication system, information regarding a first modulation scheme applied to a frequency domain in a serving base station is received from the serving base station. A signal of the frequency domain is received. A second modulation scheme is set by estimating a modulation scheme applied to the frequency domain in at least one neighbor base station from the received signal. Channel state information is generated by estimating the received signal. An operation for selecting whether to use interference cancellation is performed using the channel state information, the first modulation scheme information and the second modulation scheme.

Abstract: A terminal is capable of transmitting an orthogonal sequence in a broadband wireless communication system. Operations of a transmitting end include generating a sequence corresponding to sequence allocation information of the transmitting end among a plurality of candidate sequences; generating a signal string corresponding to the sequence; and transmitting the signal string over a channel defined for transmission of the signal string.

Abstract: A Log-Likelihood Ratio (LLR) generating apparatus and method in a communication system using a spatial multiplexing scheme. The reception method includes acquiring at least one estimated transmit vector by demodulating a receive vector using at least one Multiple Input Multiple Output (MIMO) detection process; selecting one of the at least one estimated transmit vector as an optimum estimated transmit vector; calculating LLRs with respect to the optimum estimated transmit vector; calculating a weight to be applied to each of elements constructing the optimum estimated transmit vector; and applying the weight to each of the calculated LLRs. Accordingly, the present invention can generate the LLRs with high reliability similar to the LLRs of a Maximum Likelihood receiver by applying the weight to the LLRs generated from the estimated transmit vector.

Abstract: An Iterative Detection and Decoding (IDD) receiving apparatus and method in a multiple input multiple output (MIMO) communication system. The IDD receiving apparatus includes an MIMO detector which generates soft decision values of coded bits by MIMO-decoding a receive vector, feedback priori information, and a list of candidate coded symbol vectors; a decoder which Soft-Input/Soft-Output (SISO)-decodes the soft decision values generated at the MIMO detector and feeds back soft decision values of the coded bits to the MIMO detector; a hard decision part which generates a coded symbol vector by performing a hard decision on the soft decision values generated at the decoder; and a list updater which generates a list of candidate coded symbol vectors using the receive vector and provides the list to the MIMO detector at a first iteration, updates the list using the coded symbol vector fed from the hard decision part, and provides the updated list to the MIMO detector at subsequent iterations.

Abstract: An apparatus and method for controlling a transmit power of a sounding signal in a wireless communication system are provided. The method includes estimating a downlink Carrier to Interference and Noise Ratio (CINR) using at least one signal received from a Base Station (BS), determining a transmit power level for a sounding signal using a target CINR for the sounding signal, wherein the target CINR is determined based on the downlink CINR and multi-target CINR information, and transmitting the sounding signal according to the transmit power level.

Abstract: A terminal is operable to transmit and receive CQI in a broadband wireless communication system. An operating method of the terminal for transmitting a CQI in a broadband wireless communication system includes requesting a band Adaptive Modulation and Coding (AMC) subchannel to a base station; after requesting the band AMC subchannel, transmitting a broadband CQI to the base station over a first control channel; and transmitting a first differential CQI relating to a band AMC allocated using the broadband CQI, over a second control channel. Thus, the overhead in the CQI feedback can be minimized and the CQI reception performance can be enhanced through the most robust encoding.

Abstract: Apparatuses and methods for transmission and reception in a Closed-Loop (CL)-Multiple Input Multiple Output (MIMO) system are provided. A codebook generation method includes determining weight vectors vi(i=1, . . . ,2L) for a codebook V(4, 1, L), where Nt of a codebook V(Nt,s,L) denotes a number of antennas, s denotes a number of streams, and L denotes a number of codebook index bits, determining a unitary matrix Ti using an i-th vector vi of the codebook V(4, 1, L), and determining an i-th matrix of the codebook V(4, 2, L) by selecting a first column of the unitary matrix Ti as a first column of a weight matrix and selecting a column selected from other columns excluding the first column of the unitary matrix Ti in a particular pattern, as a second column of the weight matrix.

Abstract: An apparatus and method for beamforming in a broadband wireless communication are provided. The apparatus includes a first calculator for determining a degradation factor to indicate a degradation degree of a target signal due to interference cancellation by using a target channel matrix and at least one interfering channel matrix, a second calculator for determining a new noise power value to be used to calculate a beamforming vector if the degradation factor is greater than or equal to a threshold, and for determining the beamforming vector by using the new noise power value, and a beamformer for performing beamforming on a signal transmitted/received with a target Mobile Station (MS) by using the beamforming vector.

Abstract: A method and apparatus for performing codebook-based precoding in a Multiple Input Multiple Output (MIMO) wireless communication system are provided. In a method for operating a Base Station (BS) in a MIMO wireless communication system, a reference signal including pilot signals, which are divided by a predefined number of bands and are multiplied by respective codes in a codebook, is transmitted. One or more Mobile Stations (MSs) destined for spatial multiple access are selected using an index of a band and CQI of the band corresponding to the index, which are fed back from one or more MSs. A precoding matrix is generated to process data streams of the selected one or more MSs.