Abstract: An apparatus and method for performing beamforming or transmitting a plurality of bit streams output through Adaptive Modulation and Coding (AMC) via a plurality of transmission antennas in a base station using a multi-antenna scheme. The apparatus and method include classifying the plurality of transmission antennas into a plurality of transmission antenna groups; selecting one of the transmission antenna groups depending on a group selection signal being fed back from a mobile station; and outputting each of the bit streams to its associated transmission antenna among the transmission antennas constituting the selected transmission antenna group.

Abstract: A data transmission method in a MIMO-OFDM communication system including at least one receiver for receiving a signal through a plurality of reception antennas and a transmitter for selecting a transmission channel using channel information being fed back from the receiver and transmitting a signal through a plurality of transmission antennas. The method includes selecting a spatial subchannel in which when bits are added by applying at least two spatial modes having different multiplexing gains for an individual subcarrier in a frequency domain, the minimum power increment is required during application of each spatial mode; allocating a spatial mode that requires the minimum total accumulated power, for each subcarrier; and selecting all subcarriers in the order of a subcarrier that requires the minimum power increment.

Abstract: The present invention provides the multiuser Multiple-Input Multiple-Output (MIMO) systems with a feedback method which includes measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas, selecting one of precoding matrixes, which has best SNRs, retrieving an index mapped to the selected preceding matrix from a predetermined mapping table, and transmitting the index with the SNRs of the selected precoding matrix. In the present invention, it is possible to reduce feedback information amount without degradation of the sum rate performance of the system since the feedback information is transmitted in a form of index implying appropriate precoding matrix and corresponding SNRs.

Abstract: Disclosed is a wireless communication apparatus and method for a multiple transmit and receive antenna system using multiple codes. In suggested detection algorithm, a successive interference cancellation (SIC) scheme is employed in both an antenna domain and a code domain by successively canceling multi-code interference (MCI). An effective transmit power allocation method suitable for the detection algorithm is suggested. Transmit power allocated to each code is calculated. The transmit power is determined as a simple ratio of power of a certain signal to power of a next code signal. Based on the calculated code transmit power, transmit power for each transmit antenna is allocated. Thus, information about transmit power calculated at a receive end is feedback to a transmit end through a feedback channel.

Abstract: A multiple-input multiple-output (MIMO) communication method and apparatus are provided. A MIMO communication apparatus includes a selected beamforming vector determining unit to determine a selected beamforming vector corresponding to a selected user, a performance information generating unit to generate performance information corresponding to where a non-selected beamforming vector is allocated to a non-selected user, and an additional beamforming vector selecting unit to select an additional beamforming vector corresponding to the non-selected user based on the performance information.

Abstract: A transmission/reception apparatus and method for reducing the amount of feedback information transmitted from a receiver in a multi-user MIMO system are provided. A transmitter determines a reference Channel Quality Information (CQI) and transmits the reference CQI to the receiver. Upon receipt of the reference CQI, the receiver compares the received reference CQI with a CQI of a stream received from the transmitter, sets a channel, over which the stream is received, to at least one of Activation and Inactivation, according to the comparison result, and transmits the set channel information to the transmitter. As a result, the receiver, even though it receives multiple streams from the transmitter, transmits to the transmitter the at least one of Activation and Inactivation information of the channel separately for each individual stream, thereby contributing to a reduction in the total amount of feedback information.

Abstract: A mobile communication apparatus including a base station and at least two mobile stations, having multiple antennas, respectively is provided. In the mobile communication apparatus, the base station restores from feedback signals transmitted from the mobile stations weight information determined in the mobile stations, generates from the restored weight information downlink control information ensuring maximum throughput to each of the mobile stations, and selects from among data of all of the mobile stations data of a desired mobile station(s) to be transmitted, based on the downlink control information. Each of each of the mobile stations has at least one mobile station antenna, the base station has at least two base station antennas, and the downlink control information includes mobile station selection information, an optimal basis matrix index, and optimal gain indices. As a result, nominal peak throughput in multi-antenna mobile communications can be efficiently achieved at low costs.

Abstract: The invention relates to a multi-transmission/reception antenna device and a multi-transmission/reception method in a multi-user and multi-cell environment. When a plurality of spatial subchannels having a multi-user and a multi-transmission/reception antenna are allocated to users (that is, user terminals), a user group to be supported and the number of users are selected in consideration of an influence of interference signals from adjacent cells. Accordingly, variability and independence of channels for users and interference signals from adjacent cells can be effectively used, thereby improving a transfer rate of a wireless communication system. The invention allows data transfer at higher speed with limited wireless resources.

Abstract: A method and system are provided for transmitting data in a multiple-input multiple-output (MIMO) communication system. A receiver sets the number of sub-streams of each column of a preceding matrix with respect to all precoding matrices of channels formed between the receiver and a transmitter and measures channel states with respect to sub-stream combinations whose number is equivalent to the number of set sub-streams. The receiver transmits data according to channel states to the transmitter after measuring the channel states with respect to the sub-stream combinations and antenna combinations representing sub-streams used upon data transmission of all the precoding matrices.

Abstract: A data displaying apparatus that can efficiently display a plurality of data on a relatively small display screen. The data displaying apparatus includes a user input unit for outputting a data display request signal if there is a data display request from a user, a memory unit for storing a plurality of data and a plurality of identification information corresponding respectively thereto, a display unit, and a controller. The controller controls the display unit to display the plurality of data.

Abstract: A transmission antenna diversity method, and a base station apparatus and a mobile station apparatus therefor in a mobile communication system are provided. In the transmission antenna diversity method, channel information is measured from signals received through the plurality of antennas used in the base station, and a channel information matrix is output. The channel information matrix is transformed according to a transform matrix composed of a complex basis vector set. Reception power with respect to the plurality of antennas is calculated based on the transformed channel information matrix. Antenna selection information obtained based on the calculated reception power is transmitted to the base station as feedback information for controlling transmission antenna diversity. Therefore, power is equally distributed to transmitting antennas, excellent performance is maintained at a high speed of movement, and reliable channel adaptation is accomplished at a low speed of movement of the mobile station.

Abstract: In multiuser Multiple-Input Multiple-Output (MIMO) systems in which a base station performs scheduling on the basis of channel information fed back from a plurality of terminals, the user scheduling method of the present invention includes calculating a metric for scheduling the users using the channel information, selecting one of at least two preinstalled scheduling schemes according to the metric, and performing the scheduling with the selected scheduling scheme. The user scheduling method of the present invention performs scheduling with one of TDMA- and STMA-based scheduling schemes which show maximum capacity in different channel environments, such that the system capacity can be optimally maintained even when the channel environment is changed.

Abstract: The present invention provides the multiuser Multiple-Input Multiple-Output (MIMO) systems with a feedback method which includes measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas, selecting one of precoding matrixes, which has best SNRs, retrieving an index mapped to the selected preceding matrix from a predetermined mapping table, and transmitting the index with the SNRs of the selected precoding matrix. In the present invention, it is possible to reduce feedback information amount without degradation of the sum rate performance of the system since the feedback information is transmitted in a form of index implying appropriate precoding matrix and corresponding SNRs.

Abstract: Disclosed is a method and apparatus for transmitting data in a cellular communication system including at least one base station that communicates with a plurality of mobile stations through a given frequency band. The method and apparatus divides the frequency band into at least two subcarrier groups each including a plurality of subcarriers; allocates at least one subcarrier group to each mobile station, and changes the subcarrier group allocated to each mobile station according to a predetermined period; and codes data to be transmitted to each mobile station with a plurality of codes, and transmits modulation symbols obtained by performing inverse fast Fourier transform (IFFT) on a plurality of subcarriers of the allocated subcarrier group.

Abstract: A multiple-input multiple-output (MIMO) communication system is provided for communication between a transmission apparatus having a plurality of transmission antennas and a reception apparatus having a plurality of reception antennas. The reception apparatus performs singular value decomposition (SVD) on channel information for a channel established to the transmission apparatus, and feeds back the SVD-decomposed channel information to the transmission apparatus. The transmission apparatus receives the SVD-decomposed channel information from the reception apparatus, performs QR decomposition on the received SVD-decomposed channel information, and sets multiple transmission antennas to be allocated to the channel, thereby performing beamforming.

Abstract: A beam and power allocation method for a MIMO system transmitting multiple data streams from a transmitter having a plurality of transmit antennas to a receiver having at least two receive antennas, the transmit antennas being grouped based on feedback information from the receiver, includes obtaining covariance matrices for respective transmit antenna group, and allocating beam and power to the transmit antenna groups according to the covariance matrices of the respective antenna groups. The power allocation method can be adapted to various partial beamforming techniques by generalizing the optimization problem as a function of transmit covariance matrices.

Abstract: Provided are a mobile communication apparatus including an antenna array and a mobile communication method. The mobile communication apparatus has a base station and a mobile station. The mobile station measures the downlink characteristics, detects physical space information and approximate long-term information, produces short-term informatio, transforms the short-term information and the physical space information into a feedback signal, and transmits the feedback signal to the base station. The base station receives the feedback signal, extracts weighted information, beamforms dedicated physical channel signals, combines pilot channel signals with the result of the beamforming, and transmits the results of the combinations to the mobile station via the antenna array. The physical space information denotes space information about the location of the mobile station with respect to the base station, and the approximate long-term information denotes long-term information.

Abstract: A data transmission method in a MIMO-OFDM communication system including at least one receiver for receiving a signal through a plurality of reception antennas and a transmitter for selecting a transmission channel using channel information being fed back from the receiver and transmitting a signal through a plurality of transmission antennas. The method includes selecting a spatial subchannel in which when bits are added by applying at least two spatial modes having different multiplexing gains for an individual subcarrier in a frequency domain, the minimum power increment is required during application of each spatial mode; allocating a spatial mode that requires the minimum total accumulated power, for each subcarrier; and selecting all subcarriers in the order of a subcarrier that requires the minimum power increment.

Abstract: An apparatus and method for performing beamforming for transmitting a plurality of bit streams output through Adaptive Modulation and Coding (AMC) via a plurality of transmission antennas in a base station using a multi-antenna scheme. The apparatus and method include classifying the plurality of transmission antennas into a plurality of transmission antenna groups; selecting one of the transmission antenna groups depending on a group selection signal being fed back from a mobile station; and outputting each of the bit streams to its associated transmission antenna among the transmission antennas constituting the selected transmission antenna group.

Abstract: A mobile communication apparatus including a base station and at least two mobile stations, having multiple antennas, respectively is provided. In the mobile communication apparatus, the base station restores from feedback signals transmitted from the mobile stations weight information determined in the mobile stations, generates from the restored weight information downlink control information ensuring maximum throughput to each of the mobile stations, and selects from among data of all of the mobile stations data of a desired mobile station(s) to be transmitted, based on the downlink control information. Each of each of the mobile stations has at least one mobile station antenna, the base station has at least two base station antennas, and the downlink control information includes mobile station selection information, an optimal basis matrix index, and optimal gain indices. As a result, nominal peak throughput in multi-antenna mobile communications can be efficiently achieved at low costs.