Abstract: An operation method of a first AN for a hybrid beamforming-based cooperative transmission in a C-RAN includes obtaining a spatial channel covariance with terminals subject to a service; selecting a set of terminals to be serviced from among the terminals subject to the service; determining a radio frequency (RF) precoding matrix by which interference between the terminals to be serviced is minimized; transferring information on the determined RF precoding matrix to a centralized processor (CP); and generating an effective channel by configuring an RF precoder based on the determined RF precoding matrix.

Abstract: Disclosed are methods for transmitting and receiving beamforming-based signals in a communication system. An operation method of a terminal may comprise transmitting capability information of the terminal to an AN; receiving first configuration information of a network cluster configured based on the capability information from the AN; transmitting an SRS in a beamforming scheme through resources indicated by the first configuration information; receiving second configuration information of a user cluster configured based on a measurement result of the SRS from the AN; and performing cooperative communication with ANs belonging to the user cluster, which are indicated by the second configuration information. Accordingly, the performance of the communication system can be improved.

Abstract: An operation method of a first AN for a hybrid beamforming-based cooperative transmission in a C-RAN includes obtaining a spatial channel covariance with terminals subject to a service; selecting a set of terminals to be serviced from among the terminals subject to the service; determining a radio frequency (RF) precoding matrix by which interference between the terminals to be serviced is minimized; transferring information on the determined RF precoding matrix to a centralized processor (CP); and generating an effective channel by configuring an RF precoder based on the determined RF precoding matrix.

Abstract: A hybrid beamforming based cooperative transmission system may comprise comprising a centralized processor (CP), access nodes (ANs) connected to the CP, and fronthaul links connecting the CP to the ANs. The CP may provide an outer precoding matrix for a first AN of the ANs, which is derived from global statistical channel state information (CSI) generated from local statistical CSI collected from the ANs, to the first AN via the fronthaul link; and the first AN may configure a radio frequency (RF) precoder of the first AN based on the outer precoding matrix, and configure a digital precoder of the first AN based on local instantaneous effective CSI between the first AN and first terminals to be served by the first AN.

Abstract: Disclosed are methods for transmitting and receiving beamforming-based signals in a communication system. An operation method of a terminal may comprise transmitting capability information of the terminal to an AN; receiving first configuration information of a network cluster configured based on the capability information from the AN; transmitting an SRS in a beamforming scheme through resources indicated by the first configuration information; receiving second configuration information of a user cluster configured based on a measurement result of the SRS from the AN; and performing cooperative communication with ANs belonging to the user cluster, which are indicated by the second configuration information. Accordingly, the performance of the communication system can be improved.

Abstract: A hybrid beamforming based cooperative transmission system may comprise comprising a centralized processor (CP), access nodes (ANs) connected to the CP, and fronthaul links connecting the CP to the ANs. The CP may provide an outer precoding matrix for a first AN of the ANs, which is derived from global statistical channel state information (CSI) generated from local statistical CSI collected from the ANs, to the first AN via the fronthaul link; and the first AN may configure a radio frequency (RF) precoder of the first AN based on the outer precoding matrix, and configure a digital precoder of the first AN based on local instantaneous effective CSI between the first AN and first terminals to be served by the first AN.

Abstract: Disclosed is an apparatus for receiving data in a communication system, including: a receiving unit configured to receive data transmitted from an access point (AP) by a multi-input multi-output (MIMO) scheme; a detecting unit configured to detect a data stream of the received data using an LQ decomposition scheme; a generating unit configured to generate channel information regarding the data stream; and a transmitting unit configured to feedback the channel information to the AP.

Abstract: A method and apparatus for allocating transmission power in a transmission terminal having at least one antenna of a multi-input multi-output (MIMO) system are provided. The method includes: measuring inter-stream interference of a plurality of streams; measuring inter-user interference of a plurality of users; and determining the transmission power based on the inter-stream interference and the inter-user interference, wherein the transmission power is determined using an iterative water-filling algorithm in which the Karush-Kuhn-Tucker (KKT) system is iteratively applied to all of the plurality of streams and all of the plurality of users. According to the present invention, several receive antennas are mounted in the MIMO system, thereby making it possible to receive multiple streams. In addition, when the multiple streams are received, transmission power may be allocated to each transmission stream.

Abstract: Disclosed is an apparatus for transmitting data in a communication system, including: a receiving unit configured to receive signals from multi-users by a multi-user-multi input multi output (MIMO) scheme and acquire channel information from the users; a calculation unit configured to calculate precoding vectors for the users using the channel information; a precoding unit configured to precode data of the users using the precoding vectors; and a transmitting unit configured to transmit the precoded data to users by the multi user-MIMO scheme.

Abstract: A method for transmitting, by a transmitting terminal, data to a receiving terminal in a wireless communication system includes: generating a first detection field including symbols modulated by using a BPSK data tone; generating a second detection field including symbols modulated such that an even numbered subcarrier and an odd numbered subcarrier have a phase difference of 90 degrees; generating a data packet including the first detection field, the second detection field, and the data; and transmitting the data packet.

Abstract: The present invention relates to a method for random beam-forming based on a codebook. The method includes generating a first random variable corresponding to a Gaussian distribution; generating a second random variable corresponding to a uniform distribution; generating a plurality of beam elements by using the first variable, the second variable, spatial correlation between channels, and indexes of transmitting antennas; and forming a beam by using the plurality of beam elements.

Abstract: A method and apparatus for allocating transmission power in a transmission terminal having at least one antenna of a multi-input multi-output (MIMO) system are provided. The method includes: measuring inter-stream interference of a plurality of streams; measuring inter-user interference of a plurality of users; and determining the transmission power based on the inter-stream interference and the inter-user interference, wherein the transmission power is determined using an iterative water-filling algorithm in which the Karush-Kuhn-Tucker (KKT) system is iteratively applied to all of the plurality of streams and all of the plurality of users. According to the present invention, several receive antennas are mounted in the MIMO system, thereby making it possible to receive multiple streams. In addition, when the multiple streams are received, transmission power may be allocated to each transmission stream.

Abstract: Disclosed is a transmitting/receiving method in a multi-user multiple-input multiple-output (MU-MIMO) channel. The transmitting method includes: performing QR decomposition on a Hermitian transpose matrix of a channel matrix to obtain a first matrix and a second matrix as a triangular matrix; obtaining a preprocessing matrix by using the first matrix; and forming an effective channel based on the preprocessing matrix by a block triangulation technique.

Abstract: A MU-MIMO method of an access point in a WLAN using multi-channels and having at least one station includes: receiving index information indicating a precoding vector for a beam selected by the station and channel quality information thereof for each one of the multi-channels; generating first channel capacity information of channel combination groups using the channel quality information wherein the channel combination groups are grouped according to a predetermined channel bandwidth of the multi-channels; and allocating resources to the station from a channel combination selected from the channel combination groups according to the first channel capacity information using the index information and the channel quality information, wherein the access point and the station previously store precoding vector information for a plurality of beams for the MU-MIMO.

Abstract: The present invention relates to a beamforming method and apparatus. A beamforming method for use in a base station for transmitting a plurality of streams through a plurality of antennas includes: receiving feedback information including information on a first codeword selected from a codebook including a plurality of codewords from each of a plurality of user terminals; grouping the plurality of user terminals by use of the feedback information from each user terminal; determining a user terminal to which a plurality of streams will be assigned of the plurality of user terminals, and determining a second codeword to be used for beamforming from the codebook by use of the feedback information of each user terminal and grouping information; and multiplying data to be transmitted through the plurality of steams by the second codeword and a unitary matrix.

Abstract: Disclosed is an apparatus for receiving data in a communication system, including: a receiving unit configured to receive data transmitted from an access point (AP) by a multi-input multi-output (MIMO) scheme; a detecting unit configured to detect a data stream of the received data using an LQ decomposition scheme; a generating unit configured to generate channel information regarding the data stream; and a transmitting unit configured to feedback the channel information to the AP.

Abstract: The present invention relates to a method of forming a random beam, and a beam forming apparatus. A quantization preprocessor and a random unitary matrix having a predetermined pattern are used to form a beam on a mobile terminal. A base station forms a beam using a codeword index of a quantization codebook received from a mobile terminal and channel quality information corresponding to the codeword index, and the mobile terminal generates the codeword index and the channel quality information using pilot signals generated by the base station. The number of pilot signals is equal to the number of transmitting antennas. Therefore, a codebook that has been known to both the mobile terminal and the base station is used, and the mobile terminal can select the codeword index for quantization, which makes it possible to selectively give diversity and thus improve the system efficiency.

Abstract: Disclosed is an apparatus for transmitting data in a communication system, including: a receiving unit configured to receive signals from multi-users by a multi-user-multi input multi output (MIMO) scheme and acquire channel information from the users; a calculation unit configured to calculate precoding vectors for the users using the channel information; a precoding unit configured to precode data of the users using the precoding vectors; and a transmitting unit configured to transmit the precoded data to users by the multi user-MIMO scheme.

Abstract: The present invention relates to a precoder and a precoding method in a multi-user multi-antenna communication System. When a transmission part (100) having a plurality of antennas transmits a plurality of signals to a receiving part (200) having an antenna, the precoder and the precoding method using the same prevents System performance degradation caused by interference signals and efficiently reduces transmission power while changing the constellation rotary angle. When the power is controlled by using the precoder, the System performance is enhanced while not damaging the structural gain of the existing multi-user multi-antenna precoder.

Abstract: The present invention relates to a multi-input multi-output (MIMO) system for enhancing transmission performance. The MIMO system uses space-time encoding and transmit antenna selection methods, and includes a transmitter (100) and a receiver (200). The transmitter (100) includes N transmit antennas (130-1, 130-4) that are more than M transmit antennas (130-1, 130-3) used for transmitting a signal to space channel, selects the M transmit antennas (130-1, 130-3) among the N transmit antennas (130-3 130-4), and transmits symbol by space-time encoding the symbol. The receiver (200) includes M receive antenna (120-1, 210-2) for receiving a signal from the space channel, detects an information symbol by using the signal received through the receive antenna (210-1, 210-2), generates transmit antenna selection information for selecting M transmit antennas (130-1, 130-3) among transmit antennas (i30-1, . . . 7130-4) with reference to a channel estimate, and returns the information to the transmitter.