Abstract: The present invention relates to a system and to a method for the cooperation among base stations, in which a communication service is provided to a plurality of communication terminals through the plurality of base stations. When channel state information of a communication terminal is acquired, a serving base station selects a serving channel code matching the channel state information from a codebook, calculates linear transform information using the serving channel code and the channel state information, and transmits the serving channel code to a cooperative base station. When the cooperative base station receives a cooperation channel code, the serving base station calculates serving weight information of the serving base station and cooperation weight information of the cooperative base station using the serving channel code and the cooperation channel code, and determines a beam forming vector by applying the linear transform information to the serving weight information.

Abstract: A transmission method and apparatus are provided for use in a wireless communication system in which a cell includes a plurality of sub-cells. A Transmission Point (TP) in the wireless communication system includes a transmitter configured to transmit a signal to each of the plurality of sub-cells through a plurality of antennas; a receiver configured to receive uplink control information from a User Equipment (UE) located within at least one of the plurality of sub-cells; and a controller configured to determine a virtual matrix for each of the plurality of sub-cells, to select a precoding matrix according to the virtual matrices of the plurality of sub-cells, to determine a cooperative transmission mode or a normal transmission mode, based on the received uplink control information, and to control the transmitter to perform downlink transmission on a sub-cell basis through the virtual matrices of the sub-cells according to the determined transmission 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: A method for operating a Mobile Station (MS) in a Multiple Input Multiple Output (MIMO) wireless communication system is provided. The method includes measuring channel quality for a serving Base Station (BS), if the channel quality is less than a threshold, measuring interference power from one or more neighbor BSs, determining a Precoding Matrix Index (PMI) and a priority metric for each neighbor BS, and feeding back at least one of the PMI, a PMI type indicator, the priority metric, and the channel quality to 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: 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 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: 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 method and apparatus for selecting a retransmission mode in a MIMO communication system are provided wherein a receiver receives m initial transmission streams from a transmitter, m being an integer of 2 or larger, channel-decodes the m initial transmission streams and checking errors in the m channel-decoded streams, selects, if at least two channel-decoded streams have errors among the m channel-decoded streams, a retransmission mode to be used for the at least two streams having errors in the transmitter, and transmits information including the selected retransmission mode to the transmitter.

Abstract: A method and apparatus for transmitting signals in a multi-hop wireless communication system are provided. A first BS transmits a signal including a first common information codeword and a first private information codeword. A second BS transmits a signal including a second common information codeword and a second private information codeword. A first RS joint-decodes the first common information codeword and the second common information codeword and decodes the first private information codeword. A second RS joint-decodes the first common information codeword and the second common information codeword and decodes the second private information codeword.

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: 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: 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: 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: Apparatuses and methods for transmitting and receiving signals in a mobile communication system are provided. A method for transmitting a signal by an evolved Node B (eNB) in a mobile communication system includes transmitting a same control channel signal to each of a plurality of Radio Units (RUs), and transmitting a different data channel signal to each of the plurality of RUs. A data channel signal transmitted to each of the plurality of RUs may be determined taking into account at least one of a location of a User Equipment (UE) that will receive the data channel signal, and load balancing.

Abstract: The present invention relates to a system and to a method for the cooperation among base stations, in which a communication service is provided to a plurality of communication terminals through the plurality of base stations. When channel state information of a communication terminal is acquired, a serving base station selects a serving channel code matching the channel state information from a codebook, calculates linear transform information using the serving channel code and the channel state information, and transmits the serving channel code to a cooperative base station. When the cooperative base station receives a cooperation channel code, the serving base station calculates serving weight information of the serving base station and cooperation weight information of the cooperative base station using the serving channel code and the cooperation channel code, and determines a beam forming vector by applying the linear transform information to the serving weight information.

Abstract: The present invention relates to a communications system and a telecommunication method thereof. In the communications system of the present invention, a communications terminal decides a precoding matrix index, in the reception of a pilot signal through a specific downlink channel, examining a channel quality information of the downlink channel according to the decided precoding matrix index, and transmitting a feedback information including the decided precoding matrix index and the examined channel quality information to a serving base station. In the communications system of the present invention, the serving base station decides a priority factor by using the examined channel quality information, in the reception of the feedback information, compares the decided priority factor with other priority factor, when receiving a backhaul information including the other priority factor from the neighboring base station.

Abstract: A method and system is disclosed that requests a retransmission through base station cooperation in a communication system. The method for performing a retransmission request includes: receiving data from a main base station; transmitting a retransmission request of the received data; and receiving the data from the main base station in response to the retransmission request. A sub base station performing cooperation communication with the main base station receives the retransmission request from the mobile station and changes the format of transmission with respect to mobile stations communicating with the sub base station. The method and system can allow only a small amount of information to be exchanged among base stations in a base station cooperation system, thereby effectively reducing inter-cell interference and increasing the probability of successfully receiving retransmitted data.

Abstract: In a Multiple-Input Multiple-Output (MIMO) communication system, a serving evolved Node B (eNB) receives a channel covariance matrix of the serving eNB and a channel covariance matrix for a first neighbor eNB with the highest interference among neighbor eNBs, from a User Equipment (UE). Received signal power information is generated for each subband-beam pair. Interference signal power information is generated for each subband-beam pair for the first neighbor eNB. The generated interference signal power information is exchanged with the first neighbor eNB for each subband-beam pair. Beam coordination information indicating a use status of each beam in each subband is generated for the UE, using the interference signal power information of the first neighbor eNB. The generated beam coordination information is exchanged with the neighbor eNB. Scheduling is performed on the UE using the generated beam coordination information and the beam coordination information of the first neighbor eNB.