Electronics and Telecommunications Research Institute

Samsung Electronics Co., Ltd.

Kt Corporation

Sk Telecom Company, Ltd.

Hanaro Telecom., Inc.

Ktfreetel Co., Ltd

Yonsei University

Seong-Rag Kim

In-Kyeong Choi

Dong-Seung Kwon

Seung-Joon Lee

Seung-Ku Hwang

Hyun-Kyu Chung

Yu-Ro Lee

Jong-Ee Oh

Kwang-Jae Lim

Hyoung-Soo Lim

Seong-Keun Oh

Choong-Il Yeh

Young-Seog Song

Jun-Young Nam

Young-Gyun Jeong

Young-Ho Jung

Yong-Hoon Lee

Hun Soon Lee

Chung-Yong Lee

Myeong-Cheol Shin

Jin-Kyu Choi

Seo-Young Lee

Hee-Goo Han

Moon-Il Lee

Jin-Ho Choi

Seung-Chul Hong

Nam-Jin Park

Jae-Wook Jung

Byung-Shik Kang

An iterative reception method and iterative receiver in a mobile communication system are provided. In order to remove inter-cell interference of a signal that is iteratively received in a multi-cell environment, a soft determination value of different cells excluding a specific cell is re-spread to be used. In addition, in order to improve reception performance of the iterative receiver that performs the interference removal by using the soft determination value, channel estimation is iteratively performed on the iteratively received signal by using a soft determination value of a previous order of the specific cell to update a channel estimation value. Accordingly, it is possible to reduce complexity of implementation and effectively remove the inter-cell interference by using the soft determination value.

Iterative reception method and iterative receiver

In an iterative receiver, a signal detector estimates interference from an estimated transmitted signal, and cancels the estimated interference from a signal received through an antenna. A decoder performs channel decoding by using the interference cancelled received signal. A soft decision unit performs a soft decision process on the transmitted signal by using the channel decoded signal. A channel estimator estimates a channel by using the soft decision applied transmitted signal and the received signal. A covariance estimator estimates covariance on the sum signal of the interference and noise by using the soft decision applied transmitted signal, the received signal, and the estimated channel. A hard decision unit determines the transmitted signal by using the channel decoded signal after interference cancellation, channel decoding, estimated transmitted signal updating, channel estimation, and covariance estimation are iterated a number of times.

Iterative receiver and method for detecting transmitted signal thereof

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 () and a receiver (). The transmitter () includes N transmit antennas (--) that are more than M transmit antennas (--) used for transmitting a signal to space channel, selects the M transmit antennas (--) among the N transmit antennas (--), and transmits symbol by space-time encoding the symbol. The receiver () includes M receive antenna (--) for receiving a signal from the space channel, detects an information symbol by using the signal received through the receive antenna (--), generates transmit antenna selection information for selecting M transmit antennas (--) among transmit antennas (i--) with reference to a channel estimate, and returns the information to the transmitter.

Multi-input multi-output system for enhancing transmission performance

A sphere decoder sets a Euclidean distance between a lattice vector obtained by using an MMSE or ZF estimate and a received signal as an initial radius, further reduces the initial radius, and searches lattices points included inside a hypersphere with the further reduced initial radius. In addition, one lattice vector having a minimum Euclidean distance is output. One dimension is selected to reduce an initial radius, and estimates in other dimensions are kept fixed, excluding the selected dimension. Then candidate lattice points are searched in the selected dimension, excluding a current estimate, such that a minimum Euclidean distance and a lattice point estimate corresponding to the minimum Euclidean distance are obtained. The initial radius is updated by the minimum Euclidean distance, and a final lattice vector is constructed by combining a lattice point estimate corresponding to the initial radius and the lattice point estimates in other dimensions.

Sphere decoder and decoding method thereof

A receiver according to an exemplary embodiment of the present invention receives a transmitted signal, converts the signal to a predetermined symbol, and estimates channel information including a channel gain of a channel of the transmitted signal. In addition, the receiver generates an intermediate processing value for decoding the signal based on the estimated channel information and the symbol, and normalizes the intermediate processing value to the channel gain to generate a reference value. The generated reference value is used for a soft-decision value for decoding the signal. In addition, when the signal is decoded by using a hard-decision value, a constellation point value that is closest to the reference values is generated and set as the hard-decision value.

Decoding method for space-time encoding transmission scheme in with multiple input multiple output system and receiving apparatus for using the method

A space-time code used for a transmitter to transmit a plurality of data symbols to a receiver in a MIMO system, the space-time code including a code word matrix for transmitting an amount of data symbols corresponding to a product of the number of transmit antennas and a spatial multiplexing rate during one block period, wherein a row index indicates combined signals transmitted through different transmit antennas and a column index indicates time slots that correspond to the number of transmit antennas, and wherein the number of data symbols allocated to each transmit antenna in a code block corresponds to the spatial multiplexing rate, and the data symbols are combined by different combining coefficients for each transmit antenna at every time slot, and simultaneously transmitted through different transmit antennas, and each transmit antenna transmits a different set of data symbols at every time slot.

Structured space-time code achieving the full diversity and full rate and generating method thereof, and multi-input multi-output system

A mobile station transmitting and receiving method and a corresponding mobile station transmitter and receiver of a smart antenna system for forming uplink eigenbeams of the OFDM/TDD (orthogonal frequency division multiplex/time division duplex), wherein OFDM symbols are received from a base station through a downlink via multiple antennas () and an FFT (fast Fourier transform) is performed on the received OFDM symbols by the FFT units (). By means of a channel estimator () the channels are estimated and a beam weight generator () generates respective beam weights from the channels of the respective pilot tones of the respective subcarriers according to the channel estimation result. A beam weight multiplier () forms the uplink beam by multiplying the respective beam weights with the output of the signal repeater () and IFFT units () generate respective OFDM symbols which are transmitted via multiple antennas () through an uplink.

Smart antenna system and method thereof for forming uplink eigenbeam of OFDM/TDD

Disclosed is a MIMO-OFDM system, wherein the transmitter comprises a serial/parallel converter for converting continuously inputted symbols of the number of subcarriers to K parallel signals; a signal reproducer for reproducing K parallel signals by the number of transmit antennas L an eigenmode generator for generating eigenbeam of the reproduced signals outputted from the signal reproducer at each subcarrier, on the basis of Nf eigenbeam forming vectors which are fed back long-term and information of a best eigenbeam forming vector at each subcarrier which is fed back short-term, through the feedback device; and a plurality of inverse Fourier converters for receiving the signals outputted from the eigenmode generator and generating an OFDM symbol.

MIMO-OFDM system using eigenbeamforming method

An interference canceller is herein disclosed wherein a baseband signal is input to a detector's fingers, and the fingers detect multi-path signals and estimate the baseband signal's channel. An MRC uses the finger's despread signal and the channel estimate to output a soft bit decision value, while a signal regenerator uses a hard bit decision value and the finger's channel estimate to regenerate the baseband signal. An SIR measurer uses a soft bit decision value and a despreader's channel estimate to measure an SIR. A signal selector compares each detector's SIR measurement value with a target SIR, and when the SIR measurement value is greater than the target SIR, it selects the detector's regeneration signal to group received signals. A subtractor subtracts the regeneration signal from the baseband signal.

Interference canceling device and method in mobile communication system

An adaptive interference suppression receiver for a DS/CDMA system includes: input signal generators outputting a part of received signals of receiver antennas that has a coding block's transfer code; adaptive filter blocks filtering a complex signal output from the input signal generators with a tap weight updated based on a constraint MMSE criterion and estimating phase and amplitude components of a specific user channel using the filtering output signal to generate a channel-estimated signal; a signal restorer combining the channel-estimated signal and the filtering output signal and restoring an original signal; a signal selector for selecting known training data signal or the restored signal; and error generators comparing the channel-estimated signal and the filtering output signal and calculating an error between the two signals.

Adaptive interference suppression receiving apparatus for space-time block coded direct sequence/code division multiple access communication system

An adaptive apparatus and method for detecting a receiving signal employing constrained minimum mean square error (MMSE) criterion as an adaptive algorithm for detecting CDMA receiving signal. The apparatus comprises an adaptive filtering means; a channel estimating means; a signal restoring means; a selecting means; a reference signal generating means; an error calculating means; and a tap weight controlling means. In the apparatus, an adaptive filter can be normally operated even if compensating a phase and amplitude of a channel at the same time.

Apparatus and method for adaptive CDMA detection based on constrained minimum mean squared error criterion

A method for canceling an interference signal by using a parallel multi-stage structure in a code division multiple access (CDMA) system, includes the steps of: a) delaying a receiving signal; b) receiving and predicting data and channel parameter from the individual user; c) regenerating the interference signal of the individual user by using the data and the channel parameter predicted by the multiple receiving and predicting; and d) canceling all the interference signals delayed and transferred through the delaying by the interference signal regenerated through the multiple interference regeneration.

Integrated receiving apparatus of subtractive interference cancellation receiver and adaptive MMSE receiver

A coherent dual-channel QPSK modulator/demodulator for a CDMA system, and modulating/demodulating methods therefor, are disclosed, in which the crosstalk interferences between an I-channel and a Q-channel are eliminated by an orthogonal spreading method, which assigns different Walsh codes to the I-channel and Q-channel. Pseudo-random modulation and pseudo-random demodulation are carried out by using one PN code so as to minimize the channel parameter estimation errors, thereby improving receiving performance.

Growing community of inventors

Daejeon, South Korea

Seong-Rag Kim