Abstract: In an orthogonal frequency division multiple access (OFDMA) communication system, a transmission apparatus connects multiple tiles, which have a 4×3 structure, along a time or frequency axis in an uplink 4-layer partial usage of subchannels (PUSC) mode, and designs pilots corresponding to one layer at one of multiple symbol positions adjacent to a first corner of the tiles and one of multiple symbol positions adjacent to a second corner of the tiles that face the first corner in a diagonal direction. In this case, null symbols are designed at the rest of the symbol positions adjacent to the first corner or the second corner where the pilots are not designed. Accordingly, a receiving apparatus can obtain n channel values from n tiles. Further, n estimated channel values are applied to a linear interpolation method, so that it is possible to estimate the entire channel value of n tiles.

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: Provided are a transmitting apparatus and a transmitting method in a multiple input multiple output system. A power allocation controller includes a block Tomlinson-Harashima precoder (BTHP) that precodes and outputs data to be transmitted to each user in a nonlinear scheme. The BTHP removes and outputs inference signals from data for each user based on the channel information that is fed back from the users. The data for each user output from the BTHP are allocated with power by the power allocation controller. The power allocation controller calculates power allocation parameters so that receiving minimum distances at receiving ends for each user that receive data through the MIMO antennas are the same, and allocates the calculated parameters to data for each user.

Abstract: A method for a transmitting terminal in a multi-user multi-antenna environment to perform precoding includes: receiving feedback information from a plurality of receiving terminals; estimating a channel between the transmitting terminal and the plurality of receiving terminals by using the feedback information; and generating a plurality of transmission symbols by applying a first nonlinear precoding method and a second nonlinear precoding method to a plurality of symbols and the estimated channel to be transmitted to the plurality of receiving terminals. The first nonlinear precoding method is used to eliminate interference between subchannels of the same receiving terminal, and the second nonlinear precoding method is used to eliminate interference between the receiving terminals.

Abstract: An access point allocates a resource for ranging to an access terminal included therein, and receives a ranging channel that includes an identifier of the access terminal and a plurality of pilots. The AP checks the access terminal by using the received identifier, and measures a round trip delay of the access terminal based on the received pilots.

Abstract: A multiple input multiple output (MIMO) iterative receiver detects a soft log likelihood ratio value from a signal outputted from a transmitter and decodes the detected soft log likelihood ratio value in order to extract a hard value and a soft value from the detected soft log likelihood ratio value. After whether or not a CRC of the hard value is acknowledged is determined, a CRC of a data burst is determined or iteration of signal demodulation of the MIMO iterative receiver is determined by feeding back the soft value or a CRC of data is performed assembling signals of the burst unit in accordance with the determination result.

Abstract: The present invention relates to a transmission interference cancellation method for a multiuser MIMO system. The method includes decomposing a channel matrix to represent formulae of permutation matrixes including a first matrix and a second matrix; determining an optimal permutation matrix among a plurality of available permutation matrixes using a norm of multiplication of the second matrix and a transmitting data vector; and determining the second matrix using the determined optimal permutation matrix and calculating a transmitting precoding vector using the determined second matrix and the transmitting data vector.

Abstract: A method of transmitting a synchronization channel is provided. A plurality of block sequences for determining at least one block identifier is generated. A plurality of subcarriers of a synchronization channel are divided into a polarity of blocks, and the plurality of block sequences are allocated to the blocks to generate a synchronization signal.

Abstract: A method for controlling transmission power of a base station in a cellular system includes: receiving a reference signal from at least one neighbor base station that is located around the base station; estimating a radio environment between the base station and the neighbor base station by using the receiving power of the reference signal; and controlling cell coverage of the base station by determining the transmission power based on the radio environment.

Abstract: A method of transmitting data from a terminal in a cellular system is provided. The data transmission method includes: calculating the transmission capacity of a predetermined number of vectors among pairs of orthogonal vectors; selecting the vector having the largest transmission capacity as a reference vector among the predetermined number of vectors; and transmitting data to a base station using the reference vector.

Abstract: A method to generate a beamforming vector by a terminal includes receiving information on a first precoding matrix and a second precoding matrix from a serving base station; and generating a beamforming vector by linearly combining the first precoding matrix and the second precoding matrix.

Abstract: The present invention relates to a method for connecting a base station and a repeater for a spatial division multiple access, and a repeating method thereof. In order to provide efficient spatial division by using a repeater, data streams are repeated by using a repeating system including at least one repeater for performing wireless communication with a terminal located in a repeating region controlled by using at least one repeating antenna and a base station including a plurality of base station antennas corresponding to the repeating antenna. In this instance, the terminal detects location information on the repeating region to which the terminal belongs by using the pilot signal transmitted by the base station or repeated by the repeater. Location information detected by the terminal is fed back to the base station so that the base station may use it for the spatial division multiple access for simultaneous transmission to many terminals.

Abstract: In a wireless communication system, a base station to perform power control may include: a user detector to detect a presence of a user terminal by monitoring whether a registration state of the user terminal served by the base station corresponds to a registration complete state, a registration maintain state, or a registration release state; a control signal generator to generate a control signal for controlling power of at least one power device among a plurality of power devices included in a predetermined group, based on the detection result; and a control signal transmitter to transmit the control signal to the at least one power device among the plurality of power devices.

Abstract: Disclosed are a method and an apparatus for controlling a femtocell base station which can effectively solve an inter-cell interference problem. A method of controlling a femtocell base station according to an exemplary embodiment of the present disclosure includes receiving pilot signals from one or more macro cell base stations located in surroundings of a femtocell and measuring intensities of the pilot signals; receiving use frequency information and pilot signal transmission power information from the one or more macro cell base stations; determining a position of the femtocell within a reference macro cell according to an intensity of a reference pilot signal having a maximum signal intensity among the received pilot signals; determining a use frequency of the femtocell according to the position of the femtocell; and determining a transmission power of the femtocell according to the use frequency and the intensity of the reference pilot signal of the femtocell.

Abstract: Disclosed are a method and apparatus of adaptive transmission signal detection based on a signal-to-noise ratio and a Chi-squared distribution for decoding a reception signal in the form of multi-streams into a transmission signal, the method comprising: receiving a reception signal vector; estimating a channel matrix of a channel that the reception signal vector experienced; performing QR decomposition based on the estimated channel matrix; calculating dimensions of divisional spaces adaptively on the basis of a signal-to-noise ratio (SNR) or a signal-to-interference noise ratio (SINR); detecting a maximum likelihood point having a maximum likelihood value among lattice points within each divisional space obtained on the basis of results from performing the QR decomposition and calculating dimension of the divisional spaces; and recovering a transmission signal vector based on the detected maximum likelihood points.

Abstract: A method for acquiring synchronization between nodes and configuring multiple physical channels in order to improve performance in the ad-hoc/mesh network is disclosed.

Abstract: In a symbol mapping method, transmission data is encoded to generate information bits and redundancy bits. An average LLR value of bits on which the information bits are mapped is different from an average LLR value of bits on which the redundancy bits are mapped.

Abstract: The present invention relates to an apparatus and a method for selection of a precoding matrix. In the present invention, a precoding matrix to enable an effective signal-to-noise ratio (ESNR) to have a maximum value with respect to a signal vector that requires retransmission is selected in a codebook and fed back to a transmitter. Accordingly, since the effective signal-to-noise ratio has the maximum value after the signal vector is retransmitted, it is possible to minimize a reception error probability of retransmission.

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: The present invention relates to a signal modulation device, a transmission method, and a code generation method. The signal modulation device includes a code storage unit including a plurality of n-bit members and storing a code with a number n or n?1 of different bits between two neighboring members, and a mapper for mapping data on symbols according to the code.