Abstract: A multiple antenna communication method and a multiple antenna communication system are provided. The multiple antenna communication method includes: determining a weighting vector with respect to a plurality of transmit antennas, using a spread spectrum code; determining a target transmission rate of each of the transmit antennas using the determined weighting vector; transmitting information associated with the target transmission rate to a multiple antenna reception apparatus; receiving, from the multiple antenna reception apparatus, channel information including information regarding whether to accept the transmitted target transmission rate information; and transmitting data to the multiple antenna reception apparatus using the received channel information.

Abstract: There are provided a multi-relay transmission apparatus and method. The multi-relay transmission apparatus includes: a source node repeatedly alternately performing a first phase in which preceding data is transmitted during a first transmission period equivalent to a transmission period during which unit frames are transmitted and a second phase in which subsequent data that follows the preceding data is transmitted during a second transmission period that follows the first transmission period; and a relay network including a plurality of relay nodes receiving data from the source node, in which, in the first phase, a predetermined relay node, among the plurality of relay nodes, receives the preceding data from the source node and the remaining relay nodes, among the plurality of relay nodes, and in the second phase, the remaining relay nodes receive the subsequent data from the source node.

Abstract: A multi-antenna system using adaptive beamforming includes a phase shift unit, a signal combination unit, a frequency down-converter, and an analog-to-digital (A/D) converter, and a beamforming control unit. The phase shift unit includes a plurality of phase shifters which shift the phases of signals received from a plurality of antennas. The signal combination unit combines phase-shifted signals output from the plurality of phase shifters. The frequency down-converter down-converts a signal output from the signal combination unit into a baseband signal. The A/D converter converts the baseband signal into a digital signal. The beamforming control unit searches for a weight vector higher than a preset threshold signal-to-noise ratio (SNR) when a reception SNR of the digital signal output from the A/D converter is lower than the threshold SNR, and changes a currently set weight vector into the searched weight vector to provide to the phase shift unit.

Abstract: A data transmission system transmitting data using a relay is provided. The relay selects a transmission terminal from a plurality of terminals connected to a base station. During a first time slot, the base station transmits base station data to the relay and the transmission terminal transmits terminal data to the relay. The relay transmits the terminal data to the base station and transmits the base station data to the transmission terminal during a second time slot.

Abstract: The present invention relates to a symbol-wise beamforming apparatus and method in an OFDM communication system using multiple antennas. A weight vector calculator calculates a transmit weight vector using a signal received through the multiple antennas as an input on the basis of channel information in the time domain and covariance matrix information about interference and noise and computes a receive weight vector using the calculated transmit weight vector. At least one of the calculated transmit weight vector and receive weight vector is transmitted to a transmission apparatus through a transmitter.

Abstract: A data transmission system transmitting data using a relay is provided. The relay selects a transmission terminal from a plurality of terminals connected to a base station. During a first time slot, the base station transmits base station data to the relay and the transmission terminal transmits terminal data to the relay. The relay transmits the terminal data to the base station and transmits the base station data to the transmission terminal during a second time slot.

Abstract: A Multiple-Input Multiple-Output (MIMO) communication system and method. The MIMO communication system includes: an antenna number determination unit to determine a number of active antennas among a plurality of transmitting antennas based on a power of a transmission signal wherein the number of active antennas is at least one and the at least one active antenna transmits the transmission signal; and a beam generator to generate the transmission signal corresponding to the number of active antennas by using channel information wherein the channel information is fed back from each of a plurality of user terminals.

Abstract: A data transmission system transmitting data using a relay is provided. The relay selects a transmission terminal from a plurality of terminals connected to a base station. During a first time slot, the base station transmits base station data to the relay and the transmission terminal transmits terminal data to the relay. The relay transmits the terminal data to the base station and transmits the base station data to the transmission terminal during a second time slot.

Abstract: There are provided an apparatus and a method for reducing a peak to average power ratio (PAPR) through the recombination of an orthogonal frequency division multiplexing (OFDM) symbol.

Abstract: Disclosed are a beam forming method and a multiple antenna system using the same. There is provided a multiple antenna system which forms optimal beam patterns through a transmission of a training sequence between a transmitter and a receiver, each including a plurality of antennas, the multiple antenna system comprising: a transmitter selecting antennas to be activated according to a level and transmitting the training sequence to a receiver through the selected antennas; a receiver selecting the antennas to be activated according to the level and transmitting to the transmitter an index of an optimal transmission weight vector significantly reducing a cost function based on the training sequence transmitted from the transmitter, wherein the transmitter selects antennas so that the beam patterns formed by the antennas selected at a q-th level (q: the index of the level) include the beam patterns formed by the antennas selected at a q+1-th level.

Abstract: A terminal device and a relay node selection method of the terminal device are described. The terminal device may sequentially compare a threshold value and an output signal to noise ratio (SNR) of a plurality of relay nodes based on a set test order, and select a relay node having an output SNR greater than the threshold value as a relay node to perform a cooperative communication.

Abstract: A beamforming apparatus for a multi-antenna system includes a phase control unit including a plurality of phase shifters which respectively control the phases of signals according to a preset phase weight vector; a signal combination unit combining the signals outputted from the plurality of phase shifters; a frequency down converter down-converting the combined signal outputted from the signal combination unit into a baseband signal; an analog/digital (A/D) converter converting the baseband signal into a digital signal; and a radio frequency (RF) beamforming control unit providing a plurality of preset phase weight vectors to the phase control unit according to a preset application sequence, deciding a maximum signal-to-noise ratio (SNR) among a plurality of SNRs corresponding to the applied phase weight vectors by using the digital signal outputted from the A/D converter, and controlling the beamforming of the phase control unit by using the maximum SNR.

Abstract: A method is provided for updating a check node in a low density parity check (LDPC) decoder, including: transmitting log-likelihood ratio (LLR) messages from variable nodes to a plurality of check nodes; decomposing the LLR messages in a plurality of node messages for each check node; and updating each check node using a modified function g(x), which is a function g?(x) comprising a sum operation of exponential functions based on the node messages.

Abstract: A multi-antenna system using adaptive beamforming includes a phase shift unit, a signal combination unit, a frequency down-converter, and an analog-to-digital (A/D) converter, and a beamforming control unit. The phase shift unit includes a plurality of phase shifters which shift the phases of signals received from a plurality of antennas. The signal combination unit combines phase-shifted signals output from the plurality of phase shifters. The frequency down-converter down-converts a signal output from the signal combination unit into a baseband signal. The A/D converter converts the baseband signal into a digital signal. The beamforming control unit searches for a weight vector higher than a preset threshold signal-to-noise ratio (SNR) when a reception SNR of the digital signal output from the A/D converter is lower than the threshold SNR, and changes a currently set weight vector into the searched weight vector to provide to the phase shift unit.

Abstract: A beamforming apparatus for a multi-antenna system includes a phase control unit including a plurality of phase shifters which respectively control the phases of signals according to a preset phase weight vector; a signal combination unit combining the signals outputted from the plurality of phase shifters; a frequency down converter down-converting the combined signal outputted from the signal combination unit into a baseband signal; an analog/digital (A/D) converter converting the baseband signal into a digital signal; and a radio frequency (RF) beamforming control unit providing a plurality of preset phase weight vectors to the phase control unit according to a preset application sequence, deciding a maximum signal-to-noise ratio (SNR) among a plurality of SNRs corresponding to the applied phase weight vectors by using the digital signal outputted from the A/D converter, and controlling the beamforming of the phase control unit by using the maximum SNR.

Abstract: A multiple antenna communication method and a multiple antenna communication system are provided. The multiple antenna communication method includes: determining a weighting vector with respect to a plurality of transmit antennas, using a spread spectrum code; determining a target transmission rate of each of the transmit antennas using the determined weighting vector; transmitting information associated with the target transmission rate to a multiple antenna reception apparatus; receiving, from the multiple antenna reception apparatus, channel information including information regarding whether to accept the transmitted target transmission rate information; and transmitting data to the multiple antenna reception apparatus using the received channel information.

Abstract: A terminal device and a relay node selection method of the terminal device are described. The terminal device may sequentially compare a threshold value and an output signal to noise ratio (SNR) of a plurality of relay nodes based on a set test order, and select a relay node having an output SNR greater than the threshold value as a relay node to perform a cooperative communication.

Abstract: A data transmission system transmitting data using a relay is provided. The relay selects a transmission terminal from a plurality of terminals connected to a base station. During a first time slot, the base station transmits base station data to the relay and the transmission terminal transmits terminal data to the relay. The relay transmits the terminal data to the base station and transmits the base station data to the transmission terminal during a second time slot.

Abstract: A Multiple-Input Multiple-Output (MIMO) relay system is provided. The MIMO relay system performs signal processing to provide requested real data to at least one selected user mobile station sequentially connected to a first relay station located in a first cell and a second relay station located in a second cell using spare frequency capacity allocated to a first base station of the first cell instead of a second base station of the second cell that drops the requested real data due to its frequency capacity being exceeded, thereby improving reliability of seamless real data input/output in relay communication, reducing call drop probability, and raising availability of frequency capacity by automatically adjusting frequency capacity allocated between cells.

Abstract: A method and apparatus for controlling signal transmission is provided. The method includes determining whether a signal to noise ratio (SNR) between a first base station and a signal receiving node is less than a threshold, and controlling the first base station and a second base station to cooperatively transmit a signal to the signal receiving node in response to the SNR being less than the threshold. Further, the second base station is located in an adjacent cell to a cell containing the first base station.