Abstract:
PURPOSE: An apparatus for frequency estimation at a OFDM system and a method thereof are provided to magnify frequency offset range by using a signal of period diagram in rayleigh fading channel environment. CONSTITUTION: An envelope curve regulating process of component generating unit(200) generates a component of envelop equality process. A integer frequency offset estimator(300) gets the fixed number frequency offset estimation value in which the sum between the consecutive period diagram makes have the maximum value. The prime number frequency offset estimator(400) gets the fraction frequency offset estimation value from the phase difference of the consecutive period diagram. The remainder frequency offset estimator(500) gets the frequency offset by using the fixed number frequency offset presumed and the period diagram corresponding to the fraction frequency offset.
Abstract:
PURPOSE: A frequency offset estimation scheme for system having a plurality of sub-carriers is provided to improve the frequency offset estimation performance in the digital broadcasting system of the OFDM base. CONSTITUTION: The OFDM symbol attainment module(310) gets at least, the consecutive OFDM symbol of 2. The symbol calculation module(320) is proceed the calculation about 'the pilot or data symbol belonging to the frequency band pitching according to a plurality of candidate fixed plural candidate integer frequency offsets. The fixed integer frequency offset determination module(330) selects the final fixed number frequency offset of a plurality of candidate fixed number frequency offsets according to the size of the calculated value by the symbol operating module.
Abstract:
본 발명에 따른 성능 분석 방법은 OFAM 신호를 센싱할 경우에, 상기 OFDM 신호의 심볼을 획득하고, 자기상관함수, CAF 및 SCD를 순차적으로 구하되, 수신 OFDM 신호의 CAF가 갖는 고정된 하나의 주기 주파수에 대한 피크값을 이용하여 스펙트럼 센싱을 하는 기법 1과, 복수 개의 주기 주파수에 대한 복수의 피크값을 이용하여 스펙트럼 센싱을 하는 기법 2 및 상기 SCD를 이용하여 스펙트럼 센싱을 하는 기법 3을 비교 및 분석하는 OFDM신호 검파를 위한 사이클로스테이셔너리티 기반 스펙트럼 센싱 기술의 성능 분석 방법으로서, 상기 OFDM 신호의 심볼을 획득하는 OFDM 심볼 획득하는 단계; 상기 OFDM 신호의 심볼을 이용하여 상기 자기상관함수를 연산하는 자기상관함수 연산단계; 상기 자기상관함수를 이용하여 CAF를 연산하는 CAF 연산단계; 상기 주기 자동 상관 함수를 이용하여 연산하는 SCD 연산단계; 상기 세 가지 기법들의 검정 통계량을 연산하는 단계; 및 최적의 기법을 선택하기 위해 상기 기법들의 검정 통계량에 기초한 SNR에 따른 비교를 통해서, 각 기법들의 스펙트럼 센싱의 성능을 판단하는 단계;를 갖추어 이루어진 것을 특징으로 한다.
Abstract:
PURPOSE: An orthogonal frequency division multiplexing(OFDM) receiver which estimates timing in a multi-path fading channel, an OFDM system including the same, and a timing estimation method thereof are provided to improve timing estimation performance by eliminating timing errors. CONSTITUTION: A first timing estimation part(110) calculates a timing metric value based on an autocorrelation function of a received signal including a baseband orthogonal frequency division multiplexing(OFDM) sample signal. The first timing estimation part calculates a first timing estimation value based on the calculated timing metric value. A second timing estimation part(120) calculates a filtered timing metric value based on a cross-correlation function between the received signal and a preamble signal in a first timing estimation range based on the first timing estimation value. The second timing estimation part calculates a second timing estimation value based on the filtered timing metric value. An optimum-timing estimation part(130) calculates an optimum-timing estimation value by comparing an amplification amount.
Abstract:
PURPOSE: A decoding method and a device for multiple-input multiple-output signal using tree divisions are provided to inspect more available candidate first among the candidates. CONSTITUTION: A decoder divides configured tree into many stages by considering the really applied decoding techniques. The decoder divides a layer into each single layer. The decoder performs computational complexity evaluation.
Abstract:
본 발명은 직교 주파수 분할 다중(Orthogonal Frequency Division Multiplexing: OFDM) 기법에 기반하는 수신 기법에 관한 것으로, 보다 구체적으로는 직교 주파수 분할 다중(OFDM) 기반의 시스템에서 정수 주파수 옵셋을 추정하는 기법에 관한 것이다. 본 발명에 따른 수신 장치는 연속하는 적어도 2 개의 직교 주파수 분할 다중(OFDM) 심볼을 획득하는 직교 주파수 분할 다중(OFDM) 심볼 획득 모듈; 상기 획득한 직교 주파수 분할 다중(OFDM) 심볼에 포함되는 다수의 파일럿 심볼 및 다수의 데이터 심볼 중 복수의 후보 정수 주파수 옵셋(offset)에 따라 결정되는 주파수 대역에 속하는 파일럿 및/또는 데이터 심볼에 대한 연산을 수행하는 심볼 연산 모듈; 및 상기 심볼 연산 모듈에 의한 연산 값의 크기에 따라 상기 복수의 후보 정수 주파수 옵셋 중에서 최종 정수 주파수 옵셋을 선택하는 정수 주파수 옵셋 결정 모듈을 포함하되, 상기 후보 정수 주파수 옵셋(offset)에 따라 결정되는 주파수 대역은, 파일럿 심볼들 전부가 송신되는 기 설정된 주파수 대역을 상기 후보 정수 주파수 옵셋(offset)에 따라 주파수 천이 시킨 대역인 것을 특징으로 한다. OFDM, 주파수 옵셋, 추정, 디지털 비디오 방송
Abstract:
PURPOSE: A method for analyzing an OFDM frequency offset estimation accuracy using a repeated training symbol is provided to select a proper method according to the situation of a system by analyzing the use results of three different methods. CONSTITUTION: An OFDM symbol is generated for a simulation to estimate a frequency offset. The generated OFDM symbol is transmitted from an AWGN(Additive White Gaussian Noise) environment or rayleight fading channel environment. A normalized frequency offset is set. The frequency offset estimation accuracy of each method through a mean square error is compared to select the optimum method. The OFDM symbol has a sample interval of 0.2 us, 1024 sub carriers, and 40 samples of a protection section.
Abstract:
PURPOSE: A spread spectrum code acquisition apparatus and a method thereof are provided to has detection probability robust to an FDFO and maintain uniform electric power regardless of an FDFO value by using the sum of two continuous correlation output values as a determination value. CONSTITUTION: Based on the comparison of a determination variable with a predetermined threshold value, it is judged whether or not a code is obtained. A code acquisition discrimination unit(340) judges based on the comparison whether or not the code is obtained. A PN code generator(350) generates a PN code and provides an asynchronous correlation unit with the generated PN code. An oscillator(360) generates a Doppler frequency offset estimation value and provides the generates the estimation value to a multiplier.
Abstract:
PURPOSE: A performance analyzing method for a CSS(Chirp Spread Spectrum) system corresponding to a tone jamming signal is provided to analyze the signal model of a CSS communication system in a tone jamming environment, thereby providing a SER analytical method. CONSTITUTION: A transmitter of a CSS(Chirp Spread Spectrum) system models a transmission signal. A received signal is modeled with the modeled transmission signal through multiple jamming signals. The modeled received signal models an output signal which has gone through a down-chirp filter in a signal space. The CSS system induces a closed shape SER(Symbol Error Rate) expression. The process which models the transmission signal is comprised as follows. The phase is falsified to a short pulse of IF at each symbol period.
Abstract:
PURPOSE: An apparatus and a method for frequency offset estimation in an OFDM system, and a method for time offset estimation are provided to estimate the high accuracy of a frequency offset if there is a time error. CONSTITUTION: In an apparatus and a method for frequency offset estimation in an OFDM system. An FFT (Fast Fourier Transform) demodulator demodulates a modulated signal through IFFT(Inverse Fast Fourier Transform). A correlation value calculation module(201) calculates a correlation value between the output from FFT and a training symbol. A threshold calculation module(204) calculates a threshold for the frequency offset estimation. A comparison calculation module(202) compares the correlation value with the threshold value.