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 and a method for beamforming in a wireless communication using a Base Station (BS) cooperative scheme are provided. The beamforming method includes exchanging channel status information with at least one cooperative BS which provides a BS cooperative service, generating a beamforming weight based on the channel status information, determining channel variation caused by a time delay in the channel status information exchange with the cooperative BS, updating the generated beamforming weight based on the channel variation, and precoding a transmit signal based on the updated beamforming weight.

Abstract: An apparatus for use in a relay wireless communication system is capable of bidirectional relaying with precoding. A Base Station (BS) includes a plurality of antennas. The BS can receive a relay signal that includes a transmit symbol vector of the BS and a transmit symbol vector of a Mobile Station (MS) from a Relay Station. The BS determines power difference values corresponding to all of symbol vectors available as the transmit symbol vector of the MS. The BS further determines the transmit symbol vector of the MS or per bit Log Likelihood Ratios using the power difference values.

Abstract: An apparatus and method for operating a Codebook Subset Pattern (CSP) of a Base Station (BS) in a Multiple Input Multiple Output (MIMO) system are provided.

Abstract: A base station is capable of transmitting a signal in a wireless communication network. The base station decides channel state information matrices of respective channels by determining a state of the channels corresponding to respective transmission antennas. The base station calculates transmission beam forming vectors for the respective transmission antennas by a combination of a dot product and a cross product of the channel state information matrices. Thereafter, the base station beam-forms signals for the respective transmission antennas by using the respective transmission beam forming vectors, and transmitting the beam-formed signals.

Abstract: A cluster-based cooperative communication system and method is provided for mitigating inter-cell interference effectively. A cluster-based cooperative communication method of a mobile station includes receiving allocation of a resource of a weighted subband mapped to one of preset cooperative base station clusters, the selected cooperative base station cluster having a group including a serving base station of the mobile station and dominant interfering base stations found by channel estimation, and communicating with the serving base station in cooperation with the dominant interfering base stations.

Abstract: A mobile communication system for modulating input data with a specific size into an OFDM (Orthogonal Frequency Division Multiplexing) symbol and transmitting the OFDM symbol through at least two different antennas. A replica generator generates replica data by cyclically-circulating the input data. An encoder generates a first antenna signal and a second antenna signal by encoding the input data and the replica data. A first IFFT (Inverse Fast Fourier Transform) block generates a first OFDM symbol by performing IFFT on the first antenna signal, and a second IFFT block generates a second OFDM symbol by performing IFFT on the second antenna signal. A first antenna transmits the first OFDM symbol, and a second antenna transmits the second OFDM symbol.

Abstract: A Mobile Station (MS) is operable to select a precoding matrix in a multi-antenna wireless communication system. The method includes receiving, from a serving Base Station (BS), information on a precoding matrix of which use is prohibited and a precoding matrix to be used by a neighbor BS, estimating an interference signal for the precoding matrix to be used by the neighbor BS, and selecting a precoding matrix to be used by the serving BS by considering the estimated interference signal from the remaining precoding matrixes except for the precoding matrix of which use is prohibited among precoding matrixes used by the serving BS.

Abstract: An apparatus and method for reducing pilot overhead in a multi-antenna system are provided. The method generates postcodes and pre-codes for streams used to transmit signals to at least two receivers. The method allocates a pilot signal to at least one of the streams, and allocates an additional pilot signal shared by at least one of the streams. The method precodes the pilot signal allocated to at least one of the streams, the additional pilot signal, and data to be transmitted to each of the receivers, based on the pre-code for each of the streams, prior to transmission.

Abstract: An apparatus and method for detecting signals based on a Lattice Reduction (LR) algorithm in a Multiple Input Multiple Output (MIMO) wireless communication system are provided.

Abstract: An apparatus and a method for efficient resource allocation using a cognitive radio communication in Orthogonal Frequency Division Multiple Access (OFDMA)-based moving networks are provided. The method includes determining a minimum transmit power value of the MRS, which enables the internal terminal to have a receive Signal to Interference and Noise Ratio (SINR) greater than a first threshold; determining a transmit power value of the MRS by taking into account the determined minimum transmit power value; determining a transmit power value of the MRS per cellular terminal, which is transmittable at maximum while exerting interference less than a second threshold on a corresponding cellular terminal; searching one or more cellular terminals having the maximum transmittable transmit power value determined per cellular terminal greater than the determined transmit power value; and borrowing and allocating a resource allocated to the searched cellular terminal to the internal terminal.

Abstract: A method for beamforming by a transmission device in a multiantenna multiuser communication system. The method includes grouping codebook indexes included in a codebook into codebook index combinations, and calculating a sum of transmission rate for each of the codebook index combinations; selecting a codebook index combination with a maximum sum of transmission rate as an optimal codebook index combination; and transmitting a codebook index corresponding to a particular reception device among codebook indexes included in the optimal codebook index combination, to the particular reception device.

Abstract: An apparatus and method for beamforming in a multi-antenna system are provided. The method includes assuming at least one codeword comprised in a codebook as a precoding weight of a reference receive end and generating post-processing weights of at least two receive ends, confirming a codeword maximizing a sum rate using the post-processing weights, generating preceding weights of the receive ends using the codeword maximizing the sum rate, and precoding a transmit signal using the generated precoding weights and transmitting the precoded transmit signal to each receive end.

Abstract: A Multiple-Input Multiple-Output (MIMO) wireless communication system is provided. A receiving end includes a selector for selecting at least one stream for a MultiUser (MU) mode; a first generator for generating per stream channel quality information for the at least one selected stream as at least one candidate for channel information for the MU mode; and a determiner for determining one per stream channel quality information of the candidates as channel information for the MU mode.

Abstract: An apparatus and method for pilot transmission in a wireless communication system are provided. The method includes generating a precode and a postcode for coordinated beamforming using channel information of one or more streams for transmitting signals to one or more receive ends, selecting one or more streams to be allocated pilots, updating the precode according to a reference point for representing an effective channel of non-selected streams orthogonal to an effective channel of the selected streams, and precoding signals transmitted through the streams.

Abstract: In the present invention, an apparatus and a method for generating feedback information for a Maximum Likelihood (ML) detection scheme in a Multiple-Input Multiple-Output (MIMO) wireless communication system are provided. An apparatus of the invention includes a generator for generating constellation difference points by converting a constellation domain representing values of symbols into a constellation difference domain representing values of distance between symbols, a calculator for calculating per stream Symbol Error Rates (SERs) using the constellation difference points, and a determiner for determining per stream Effective Signal to Noise Ratios (ESNRs) using the per stream SER.

Abstract: An apparatus and method for supporting a multiple antenna service in a wireless communication system are provided. The apparatus includes at least one antenna, a form determining unit for determining a form of an MS, and an antenna constructing unit for constructing an antenna structure according to the form of the MS using the at least one antenna.

Abstract: A mobile communication system modulates input data with a specific size into an OFDM symbol and transmits the OFDM symbol through an antenna. In the mobile communication system, a replica generator generates OFDM symbol data by cyclic-circulating the input data by a predetermined cyclic circulation distance d, and outputs a stream of the input data and the replica data as a data stream.

Abstract: A Maximum Likelihood (ML) detection apparatus and method in a wireless communication system are provided, in which a Euclidean distance are calculated using at least one of channel matrix information, noise power information and modulation order information of each stream, Pairwise Error Rate (PER) are calculated using the Euclidean distance, an error probability of the each stream is calculated using the PER, the error probability of the each stream is ordered and sorted, and ML detection is performed using a result of the ordering and sorting.

Abstract: A multiple-input multiple-output (MIMO) wireless communication system includes a first calculator for calculating pairwise error rates (PERs) for each modulation scheme combination which comprise elements smaller than or equal to receive antennas in number; a second calculator for calculating symbol error rates (SERs) for the each modulation scheme combination using the PERs; a converter for converting the SERs to effective signal to noise ratios (SNRs); and a determiner for determining one among sets of effective SNR per stream acquired from the modulation scheme combinations, as a final effective SNR per stream.