Abstract: A method for assigning a single frequency sub-channel to a plurality of MSs (Mobile Stations) in an OFDM (Orthogonal Frequency Division Multiplexing) system utilizing SDM (Spatial Division Multiplexing) with multiple transmit/receive antennas. In the method, a BS (Base Station) can effectively assign a pilot channel to estimate a downlink channel. The BS divides the single frequency sub-channel into a plurality of spatial channels, and sequentially assigns the plurality of spatial channels to the MSs having the maximum communication capacity, thereby transmitting signals of the MSs through the single frequency sub-channel.

Abstract: A method for receiving a signal by using M multiple beams in a multi-antenna system including N antenna elements, is provided in and embodiment of the present application. The method includes setting, by M beams, a beam direction for the M beams and a modulation frequency for frequency modulation of a beam response and generating the M beams according to the beam direction and the modulation frequency set by the beams. M beam responses are generated for a receiving signal by using the generated M beams and the generated M beam responses are frequency modulated by using the modulation frequency set by the beams. The frequency-modulated M beam responses are band-pass filtered so as to separate the M beam responses and the separated M beam responses are respectively demodulated.

Abstract: One or more embodiments provide a method for controlling array antenna device in a base station (BS) in a communication system. The method includes determining whether to perform a calibration operation for BSs while operating in one of a normal mode and an interference control mode. The method also includes transiting from the one of the normal mode and the interference control mode to a calibration mode based on the determining result of whether to perform the calibration operation for the BSs. A reference antenna among antennas included in the array antenna device is used in all of the normal mode, the interference control mode, and the calibration mode.

Abstract: A beamforming method is provided. The beamforming method includes determining different beams for pieces of user equipment based on channel information fed back from the pieces of user equipment, predicting beam qualities of the pieces of user equipment for the beams, determining whether the beam qualities satisfy Quality of Service (QoS) for the pieces of user equipment, generating a wide nulling beam by applying wide nulling to a second beam having a side lobe acting as interference against one first beam, when the beam quality of the first beam does not satisfy the QoS; predicting beam qualities for the beams including the wide nulling beam instead of the second beam, and simultaneously communicating with the user equipment through the beams including the wide nulling beam instead of the second beam, when the beam qualities for the beams including the wide nulling beam instead of the second beam satisfy the QoS.

Abstract: A method for receiving a signal by using M multiple beams in a multi-antenna system including N antenna elements, is provided in and embodiment of the present application. The method includes setting, by M beams, a beam direction for the M beams and a modulation frequency for frequency modulation of a beam response and generating the M beams according to the beam direction and the modulation frequency set by the beams. M beam responses are generated for a receiving signal by using the generated M beams and the generated M beam responses are frequency modulated by using the modulation frequency set by the beams. The frequency-modulated M beam responses are band-pass filtered so as to separate the M beam responses and the separated M beam responses are respectively demodulated.

Abstract: A beamforming method is provided. The beamforming method includes determining different beams for pieces of user equipment based on channel information fed back from the pieces of user equipment, predicting beam qualities of the pieces of user equipment for the beams, determining whether the beam qualities satisfy Quality of Service (QoS) for the pieces of user equipment, generating a wide nulling beam by applying wide nulling to a second beam having a side lobe acting as interference against one first beam, when the beam quality of the first beam does not satisfy the QoS; predicting beam qualities for the beams including the wide nulling beam instead of the second beam, and simultaneously communicating with the user equipment through the beams including the wide nulling beam instead of the second beam, when the beam qualities for the beams including the wide nulling beam instead of the second beam satisfy the QoS.

Abstract: One or more embodiments provide a method for controlling array antenna device in a base station (BS) in a communication system. The method includes determining whether to perform a calibration operation for BSs while operating in one of a normal mode and an interference control mode. The method also includes transiting from the one of the normal mode and the interference control mode to a calibration mode based on the determining result of whether to perform the calibration operation for the BSs. A reference antenna among antennas included in the array antenna device is used in all of the normal mode, the interference control mode, and the calibration mode.

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: Provided are an apparatus and a method for providing a relay service in a wireless communication system. The apparatus includes a modulator, an encoder, and a transmission unit. The modulator modulates a transmission signal according to a modulation degree. The encoder encodes a modulation symbol provided from the modulator using a convolution code of a ring domain. The transmission unit transmits the signal provided from the encoder to a relay station. The relay station detects a signal where signals received from different transmission ends are added in a real domain, and relays the detected signal, thereby providing a relay service without an additional time resource.

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 supporting relaying in a wireless communication system are provided. The apparatus and method include a transmitting apparatus which acquires channel information between the transmitting apparatus and an RS, pre-encodes a transmission signal to be transmitted to the RS with the channel information, transmits the pre-coded signal to the RS, and acquires, upon receipt of a signal from the RS, a signal transmitted by a receiving apparatus by eliminating the transmission signal transmitted to the RS from the received signal. Accordingly, the apparatus and method improve system capacity gain without adding time resources.

Abstract: An optimum perturbation apparatus and method in a multi-antenna, multi-user communication system are provided. In the optimum perturbation method, upon receipt of modulation symbols, channel responses are decomposed into eigenvalues and eigenvectors by Single Value Decompositin (SVD) and a distortion value of the modulation symbols is estimated using the eigenvectors and the eigenvalues to minimize noise and interference power. The modulation symbols are precoded by combining the modulation symbols with the estimated distortion value.

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 optimum perturbation apparatus and method in a multi-antenna, multi-user communication system are provided. In the optimum perturbation method, upon receipt of modulation symbols, channel responses are decomposed into eigenvalues and eigenvectors by Single Value Decompositin (SVD) and a distortion value of the modulation symbols is estimated using the eigenvectors and the eigenvalues to minimize noise and interference power. The modulation symbols are precoded by combining the modulation symbols with the estimated distortion value.

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 are an apparatus and a method for providing a relay service in a wireless communication system. The apparatus includes a modulator, an encoder, and a transmission unit. The modulator modulates a transmission signal according to a modulation degree. The encoder encodes a modulation symbol provided from the modulator using a convolution code of a ring domain. The transmission unit transmits the signal provided from the encoder to a relay station. The relay station detects a signal where signals received from different transmission ends are added in a real domain, and relays the detected signal, thereby providing a relay service without an additional time resource.

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: A transmission method based on random beamforming. A base station receives, from mobile stations, feedback information including channel-by-channel transmission rates for a weight vector arbitrarily set by the base station. The base station compares transmission rates of identical channels received from the mobile stations. The base station allocates an associated channel to a mobile station with a large transmission rate and transmits a signal through the allocated channel. The transmission method based on random beamforming can improve fairness and efficiency of a resource allocation by simultaneously allocating different channels to multiple terminals and can increase a total system capacity through the improved fairness and efficiency.

Abstract: Disclosed is a method for configuring transmission antenna groups in a mobile communication system with multiple transmission antennas and multiple reception antennas. The method includes the steps of: receiving a first matrix having a size of ‘Nt×Nt’, which corresponds to Nt number of transmission antennas, fedback from the mobile terminal, generating combinations of sub-matrixes of the first matrix corresponding to Nr number of reception antennas, and calculating sums of maximum eigenvalues; determining combinations of the sub-matrixes having a maximum value from among the calculated sums of eigenvalues to be transmission antenna groups for the Nt number of transmission antennas; and transmitting different relevant symbols from each other through the transmission antenna groups.

Abstract: A method for assigning a single frequency sub-channel to a plurality of MSs (Mobile Stations) in an OFDM (Orthogonal Frequency Division Multiplexing) system utilizing SDM (Spatial Division Multiplexing) with multiple transmit/receive antennas. In the method, a BS (Base Station) can effectively assign a pilot channel to estimate a downlink channel. The BS divides the single frequency sub-channel into a plurality of spatial channels, and sequentially assigns the plurality of spatial channels to the MSs having the maximum communication capacity, thereby transmitting signals of the MSs through the single frequency sub-channel.