Abstract:
PURPOSE: A repeater selecting method in cooperative communication, a receiver, and a cooperative communication system thereof are provided to select a repeater by using SNR(Signal to Noise Ratio). CONSTITUTION: A receiver(131) receives a CRC signal for the signal of a transmitted from a plurality of candidate repeaters. A ranking setting unit(133) analyzes the relay performance of the candidate repeaters through the CRC signal. The ranking setting unit sets an access priority ranking for the plurality of candidate repeaters. A transmitter(132) generates a final repeater selecting signal according to the access priority. The transmitter transmits the generated final repeater selecting signal to the transmitter. [Reference numerals] (131) Receiver; (132) Transmitter; (133) Ranking setting unit
Abstract:
PURPOSE: A frequency error estimation method in a UWB-OFDM[UltraWide Band-Orthogonal Frequency Division Multiplexing] system and an apparatus thereof, capable of employing a cyclic delay diversity technique are provided to estimate a correct frequency error. CONSTITUTION: A transmission end(100) transmits symbols to each transmission antenna using a cyclic delay diversity technique when the cycle of the same OFDM symbol is delayed in a time axis. A receiving end(200) includes a Fourier transforming unit(210), a sub-band selector(220), a self signal correlation unit(230), a RFO[Residual Frequency Offset](240), and a SFO[Sampling Frequency Offset](250). The Fourier transforming unit transforms OFDM symbols transmitted from the transmission end in a Fourier transforming way at a high speed. The sub-band selector senses all channel powers in distinguishable sub-bands and estimates or selects a sub-band which has a maximum channel power. The self signal correlation unit produces a self correlation value about a pilot symbol in the corresponding OFDM symbol transmitted through the selected sub-band. The RFO estimator and the SFO estimator estimate the error of a residual frequency or the error of a sampling frequency by using the produced self correlation value. [Reference numerals] (100) Transmission end; (110) Cycle delay selector; (200) Receiving end; (210) Fourier transforming unit; (220) Sub-band selector; (230) Self signal correlation unit; (240) RFO estimator; (250) SFO estimator
Abstract:
본 발명은 LR을 이용한 MIMO 시스템의 신호 검출 방법 및 그 장치에 관한 것이다. 본 발명에 따른 LR을 이용한 MIMO 시스템의 신호 검출 방법은, 다중 안테나를 가지는 송신 단말로부터 L-QAM 방식으로 신호를 수신하는 단계, 상기 수신 신호를 QR 분해하여 정규직교행렬 성분을 제거하는 단계, 상기 수신 신호와 상기 L-QAM 방식으로 전송되는 L개의 심볼과의 유클리드 거리를 구하는 단계, 상기 유클리드 거리가 짧은 V개의 후보 심볼을 첫번째 후보 심볼로 선택하는 단계, LR(lattice reduction) 방식을 이용하여 상기 V개의 후보 심볼 각각과 후보 열을 이루는 나머지 미검출 심볼들을 검출하는 단계, 그리고 ML(maximum likelihood) 방식을 이용하여 상기 V개의 후보 열들 중에서 전송 신호와 가장 가까운 신호열을 선택하는 단계를 포함한다. 이와 같이 본 발명에 따르면 MIMO 시스템에 있어서, 전송되는 신호의 첫번째 V개의 후보 심볼을 정하고, 그에 따른 나머지 심볼들을 LLL 알고리즘을 통해 채널의 condition number를 줄이고 수정된 채널을 가지고 신호를 검출함으로써, 기존의 LLL 알고리즘을 통한 기본적인 검출 기법보다 비트오율이 훨씬 향상되고 정확하게 송신 신호를 검출할 수 있다.
Abstract:
PURPOSE: A method for detecting a signal of a MIMO(Multiple Input Multiple Output) system and a device thereof are provided to detect a signal which is transmitted through a multiple transmission antenna with low complexity and high accuracy. CONSTITUTION: An aligning unit(220) aligns channel coefficients included in a transmission channel according to the size of a pseudo reverse matrix. A QRD-M detecting unit(230) successively selects M candidate rows by a QRD-M type wherein the selection is performed from a candidate row whose pseudo reverse matrix is small to a candidate row whose pseudo reverse matrix is large. An LR(lattice Reduction) detecting unit(240) detects the remaining undetected symbols for the M candidate symbols using an LR type. An ML(Maximum Likelihood) detecting unit(250) selects a signal row nearest a transmission signal among the M candidate symbols using an ML type.
Abstract:
PURPOSE: A base station cooperation transmitting method and system thereof based on OFDM(Orthogonal Frequency Division Multiplexing) are provided to minimize the transmission ratio between a relay and a user terminal. CONSTITUTION: First and second base stations(110,120) perform cooperative communication. An RS(Relay Station)(130) is installed between first and second base stations. The first and second base stations transmit a signal to the relay in a G-STBC(Groupwised-Space Time Block Code) mode. The first and second base stations modulate the transmission signal in a BPSK, QPSK, 16QAM, or 64QAM.
Abstract:
PURPOSE: A hybrid cyclic delay diversity cooperative communication system is provided to select the number of repeaters without an additional structure change in a receiving part by using OFDM(Orthogonal Frequency Division Multiplexing). CONSTITUTION: A transmitter(S) transfers signal based on OFDM. A plurality of repeaters(R1-RM) transmits signals from each group after performing cyclic delay. A receiver estimates an original signal by receiving signals from the repeaters through a plurality of antennas. The transmitter and the repeater has a single antenna.
Abstract:
PURPOSE: A cooperative communication system using OFDM(Orthogonal Frequency Division Multiplexing) is provided to transmit multi symbols by grouping as one frame. CONSTITUTION: A plurality of IFFT(Inverse Fast Fourier Transform) processing unit(130) performs modulation process about M groups included in the OFDM symbol of the parallel configuration. A parallel to serial converter(140) changes the OFDM symbol processed with IFFT into the serial type. The parallel to serial converter inserts a common cyclic prefix to a front of data frame of each group. A transmission unit(150) changes the OFDM symbol in which the cyclic prefix is inserted into the analog type. The transmission unit transmits the transformed OFDM symbol to the relay.
Abstract:
다중 전송률을 제공하는 다중 반송파 시스템 및 그 방법이 개시된다. 본 발명에 따른 다중 반송파 송신기는 피드백 채널을 통해 수신되는 채널 환경값을 이용하여 전송 방식을 선택하고, 선택된 전송 방식에 따른 사용자 수를 결정하는 전송 방식 선택부, 채널 환경값을 이용하여 송신할 데이터의 반복 전송 회수를 결정하는 반복 설정부 및 전송 방식, 사용자 수 및 상기 반복 전송 회수에 따라 결정된 전송률로 상기 데이터를 전송하는 다중 전송률 전송부를 포함한다. 다중 전송률, 다중 반송파, 채널 환경값, 전송 방식, 다중 사용자