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: Disclosed a transmission apparatus in a CDMA mobile communication system. Transmission frames each have a plurality of time slots, and each of the time slots includes two data parts having the same length, a midamble intervening between the data parts, and a guard period for dividing the consecutive time slots. The transmission apparatus modulates the frames into a radio signal with a modulation signal and transmits the modulated radio signal using a plurality of antennas. A power amplifier amplifies the radio signal. A controller generates a switching control signal in a guard period of time slots of a frame associated with the radio signal amplified by the power amplifier. A switch switches the amplified radio signal from the power amplifier between a first and a second antenna in response to the switching control signal.

Abstract: Disclosed is a transceiving apparatus and method in which a space frequency block coding (SFBC) technique is applied to the SC-FDE technique. The transceiving method encodes an input signal into frequency-domain blocks so as to output at least two signal blocks in parallel to each other, inserts a cyclic prefix (CP) into the output signal blocks, and outputs the signal blocks through the same sub-channel using a corresponding antenna.

Abstract: A receiving apparatus and method of a Maximum Likelihood (ML) scheme in a Single-Carrier (SC) system are provided. The apparatus includes at least two antennas, at least two Orthogonal Frequency Division Multiplexing (OFDM) demodulators, at least two subcarrier mappers, at least two OFDM modulators, and a detector. The antennas receive signals. The OFDM demodulators convert the signals into frequency domain signals. The subcarrier mappers confirm signals mapped to frequency domain subcarriers. The OFDM modulators convert the signals into time domain signals. The detector constructs at least one set for candidate transmission symbols and detects receive signals through ML detection using the set.

Abstract: An apparatus and method for channel estimation and CP reconstruction in an OFDM-STBC mobile communication system are provided. An ISI canceller cancels ISI signal components from first and second received symbol sequences. A cyclicity restorer cancels ICI signal components from the ISI-cancelled first received symbol sequence and the ISI-cancelled second received symbol sequence. A recoverer acquires the recovered sequence estimates of the ICI-cancelled first received symbol sequence and the ICI-cancelled second received symbol sequence by decoding. The ICI cancellation of the ISI-cancelled first and second received symbol sequences and the ISI cancellation of the second received symbol sequence are iterated a predetermined number of times.

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 user allocating apparatus and method in a multiple antenna mobile communication system supporting multi-user diversity is provided. Each user calculates effective Signal-to-Interference Noise Ratios (SINRs) and bit loading over every possible detection order and selects a detection order maximizing the number of channels with a minimum product of the minimum symbol distance of a modulation scheme and an effective SINR, thereby minimizing an average error probability. A base station receives detection orders from users and selects a user with a maximum detection order value. The base station then transmits data to the selected user using modulation schemes determined by the user for the transmit antennas.

Abstract: A method and apparatus for parallel structured Latin square interleaving in a communication system are provided. The method includes dividing input information bits into sub-blocks according to a parallel processing order, generating a first Latin square matrix or a second Latin square matrix by comparing the parallel processing order with a predetermined threshold, and interleaving by reading out the information bits divided into the sub-blocks according to the generated Latin square matrix.

Abstract: Disclosed is a method for estimating the velocity of a mobile station in Rician fading environments in which a direct wave exists. Cellular mobile communication environments include two environments, Rician fading environments in which a direct wave exists and Rayleigh fading environments in which a direct wave does not exist. Generally, many methods for estimating the velocity of a mobile station have been known in Rayleigh fading environments. However, in Rician fading environments in which a direct wave exists, many errors occurs in estimating the velocity of a mobile station due to difficulty in estimation of a Rician coefficient K and an incident angle ?0. According to the invention, a method is provided wherein error is mostly eliminated in estimating the velocity of a mobile station by obtaining a maximum Doppler frequency of the mobile station, even without directly obtaining a Rician coefficient K and an incident angle ?0.

Abstract: An apparatus is provided for reducing a peak-to-average power ratio (PAPR) in a wireless communication system having multiple transmit antennas. A symbol generator generates symbols to be transmitted via the multiple transmit antennas, and a PAPR calculator calculates a PAPR value for each symbol. A detector detects a maximum PAPR value among the PAPR values of the symbols. A controller outputs a control signal to reduce a PAPR value of a corresponding symbol when the detected maximum PAPR value exceeds a reference PAPR value. A PAPR reducer reduces the PAPR value of the corresponding symbol upon receipt of the control signal.

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 broadband wireless communication system is provided. A transmitting end of the broadband wireless communication system includes: a controller for receiving a plurality of Orthogonal Frequency Division Multiple Access (OFDMA) symbols, and for generating the same number of symbol sets corresponding to the OFDMA symbols wherein each symbol set includes a plurality of OFDMA symbols having various Peak to Average Power Ratios (PAPRs) according to several phase-shifting patterns, a selector for grouping the plurality of OFDMA symbols into symbol groups according to the same phase-shifting pattern of the several phase-shifting patterns, and for finding maximum peak value in each symbol group, and a transmitter for transmitting the symbol group having a minimum value selected from among the maximum peak values of the symbol groups.

Abstract: A receiving apparatus in an OFDM communication system, in which the receiving apparatus includes a serial-to-parallel converter that converts a serial signal received through an antenna to parallel signals. A pre-processor processes an nth symbol converted in the serial-to-parallel converter using an (n?1)th symbol and an (n+1)th symbol. A Fourier transformer Fourier-transforms the output of the pre-processor and an equalizer equalizes a Fourier-transformed signal. A deinterleaver deinterleaves an equalized signal, a decoder decodes a deinterleaved signal, and a parallel-to-serial converter converts parallel decoded signal to a signal stream.

Abstract: An apparatus and method for data transmission in an Orthogonal Frequency Division Multiplexing (OFDM) communication system are provided.

Abstract: A method and apparatus for allocating resources for a mobile station in a communication system is provided. The method includes determining if a mobile station within a cell is located in one of a first region corresponding to a cell center, a third region corresponding to a cell edge, and a second region corresponding to an area between the first and third regions, allocating frequency resources within an entire frequency band to the mobile station when the mobile station is located in the first region, wherein the entire frequency band comprises at least a first frequency band and a second frequency band, allocating frequency resources within the first frequency band to the mobile station when the mobile station is located in the third region, and allocating frequency resources within the second frequency band to the mobile station when the mobile station is located in the second region.

Abstract: In the ICI cancellation method for OFDM communication system, a receiver performs channel estimation using pilot subcarriers included in transmission signals transmitted from at least one transmitter. The transmitter generates the transmission signal in which pilot subcarriers and data subcarriers are regularly arranged, performs preceding on the transmission signal, modulates the pre-coded transmission signal into an OFDM symbol, and transmits the OFDM symbol. The receiver receives the OFDM symbol; demodulates the OFDM symbol, detects the pilot subcarriers from a demodulated signal, estimates channels using the pilot subcarriers, and restores the transmission signal using the estimated channels.

Abstract: An apparatus and method for transmitting data on a plurality of frequency sub-channels for a plurality of successive symbol periods through a plurality of transmit antennas in an OFDM system. In the data transmitting apparatus, an S/P converter converts information symbols received from a data source to an information symbol vector, a coder generates at least one code symbol vector using the information symbol vector in at least one symbol period, an IFFT unit generates at least as many transmission signal vectors as twice the number of code symbol vectors generated in the coder for the one symbol period, a plurality of P/S converters each convert the transmission signal vectors to a transmission signal stream, and a guard interval inserter inserts a guard interval into each of the transmission signal streams received from the P/S converters.

Abstract: An adaptive modulation scheme relating to an RA problem for maximizing the transmission rates of all users for maximum transmission rates in an OFDMA system including some users requiring to use services at fixed data rates. The scheme proposes introduction of an adaptive modulation using linear programming into an existing scheme for a system including a single kind of users, thereby enabling simultaneous execution of the adaptive modulation for all users in a system including two kinds of users. Further, the invention proposes another scheme of sequentially allocating subchannels to the users when the fixed transmission rate has a sufficiently small value, in order to reduce the complexity.

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: An apparatus and method for performing distributed spatial multiplexing and distributed spatial diversity in a multi-hop relay system are provided. In the multi-hop relay system, a transmitter includes an outer coder for performing outer coding on transmission data, an outer interleaver for interleaving data received from the outer coder, an inner coder for dividing data received from the outer interleaver into a plurality of frames and performing inner coding on the divided frames, and a transmitting unit for transmitting hierarchically coded frames received from the inner coder to respective Relay Stations (RSs).