Abstract:
PURPOSE: A method of estimating a frequency offset in a radio communication system is provided to prevent a sudden degradation of an estimated performance in the OFDM based CR system by providing strong and excellent estimated performance in various noise environments. CONSTITUTION: In the entire-domain of frequency offset value, frequency offset of P units are respectively estimated instead of estimating one of frequency offset in the local range of P units. A frequency offset which has the smallest error is determined as a final frequency offset value. A frequency offset estimator(200) comprises local optimal estimator of P units which respectively estimates frequency offset of P units. Local optimal estimator(210) provides an initial value of predetermined offset which is respectively corresponding in the local range. A frequency offset is respectively estimated by using an equation. A frequency offset estimator determines a frequency offset which has the smallest error among the frequency offset of P units as a value of final frequency offset. [Reference numerals] (AA) Receiving signal; (BB) Selecting ε^_p having the minimum |ε^_p-ε_p|; (CC) Final estimated value ε^
Abstract:
PURPOSE: A frequency offset estimating method and an apparatus performing the same are provided to adaptively measure frequency offset based on frequency offset estimating method. CONSTITUTION: A frequency offset is estimated by using a plurality of frequency offset estimating methods(S200). The first estimating method includes a step for determining a frequency offset candidate value. The final frequency offset of the received OFDM symbol is calculated by using a frequency offset value(S210). The calculated frequency offset has respectively different value through a plurality of frequency estimating method. [Reference numerals] (AA) Start; (BB) End; (S200) Estimating a frequency offset by using a plurality of frequency offset estimating methods; (S210) Calculating the final frequency offset of a received OFDM symbol by using a frequency offset value calculated through the plurality of frequency estimating methods
Abstract:
PURPOSE: A multi-step timing offset estimating method and an OFDM receiver are provided to obtain randomness of a signal path component by controlling variation due to a signal path component. CONSTITUTION: An OFDM terminal performs a first estimation step(130) estimating a timing spot of a signaling path having a large power signal. The OFDM terminal estimates timing offset of an input signal through a second estimation step(150). An OFDM signal is input to the receiver through a predetermined channel. The first estimation step includes a step for executing timing offset estimation based on a correlation function. [Reference numerals] (130) First estimation step; (150) Second estimation step; (AA) First timing offset estimation; (BB) Local signal generator; (CC) Clock; (DD) Relation; (EE) Delay; (FF) Sample average; (GG) Sample distribution
Abstract:
PURPOSE: A performance analysis method of a CSS system based on diversity combining techniques over multipath channels is provided to compare BER performance of DM-BPSK(Binary Phase Shift Keying) system of MRC, EGC(Equal Gain Combining) or SC(Selection Combining) base and analyzing BER performance of EGC and SC diversity combining technique. CONSTITUTION: A CSS(Chirp Spread Spectrum) system executes modeling of a first received signal of a rake receiver(S100). The CSS system uses a MRC(Maximal Ratio Combining) technique and a SC(Selection Combining) technique(S300) on a second received signal and a presumed channel coefficient. The CSS system calculates SINR(Signal-to-Interference plus Noise Ratio) using a generated decision variable(S400). Based on one among plural diversity combining techniques, the CSS system calculates BER(Bit Error Rate) of multipath channel(S500). [Reference numerals] (AA) Start; (BB) End; (S100) Modeling a first receiving signal, which is received in a rake receiver through a multi-path channel, in a CSS system; (S200) Generating a second receiving signal by correlation function operation of a first receiving signal and a chirp signal; (S300) Generating a determination variable for a transmission signal by applying the second receiving signal and an estimated channel coefficient to a diversity combining technique; (S400) Calculating an average SINR per channel using the determination variable; (S500) Calculating the BER of the multi-path channel based on the diversity combining technique
Abstract:
본 발명은 협력 통신 시스템 및 그의 OFDM 심볼 전송 방법에 관한 것으로, 소스 노드에서의 심볼 조합과 릴레이 노드에서의 간단한 부호 반전 및 허수곱 연산을 이용하여 시간 전환 및 이동 연산을 사용하지 않아도 목적지 노드에서 알라무티 부호 구조를 생성하여 협력 다이버시티 이득을 얻을 수 있는 효과를 기대할 수 있다. 또한, 본 발명에서는 릴레이 노드에서 순환 전치를 추가 연산하여 릴레이 노드의 시간 동기화 오류 문제를 극복할 수 있는 효과를 기대할 수 있다.
Abstract:
본 발명은 다중경로 페이딩 채널에서 OFDM 시스템에 발생할 수 있는 타이밍 에러를 제거하여 타이밍 오차 추정의 성능을 향상시킬 수 있는 효과가 있다. 이를 위해 특히, 수신 신호의 자기상관 기법 및 프리앰블 간의 상호상관 기법을 이용하고, 타이밍 메트릭과 필터함수를 통해 단계별 타이밍 오차 추정치를 구하여 최종 타이밍 오차 추정치를 얻을 수 있는 다중경로 페이딩 채널에서 타이밍 오차 추정이 가능한 OFDM 수신기, 이를 포함하는 OFDM 시스템 및 이들의 타이밍 오차 추정방법이 개시된다.
Abstract:
PURPOSE: An orthogonal frequency division multiplexing(OFDM) receiver which estimates timing errors in a multi-path fading channel, an orthogonal frequency division multiplexing system including the same, and a timing error estimation method thereof are provided to prevent inter-symbol interference(ISI), thereby correctly recovering a received signal. 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) samples 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. 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 method for tracking a BOC signal and a system thereof is provided to supply a correlation function having a narrow peak by using a base signal. CONSTITUTION: In a method for tracking a BOC signal and a system thereof, an initial correlation function between an BOC signal and all baseband signals of the BOC(Binary Offset Carrier) signal is generated(S1). A final correlation function having removed peak is generated using initial correlation function(S2). The final correlation function having no peak is applied to a discriminator(S3). A signal tracking is performed using the discriminator(S4).
Abstract:
본 발명에 따른 OFDM 시스템에서의 훈련 심볼을 이용한 시간 옵셋 추정 방법은, 기법 1, 기법 2, 기법 3에 대해, 시간 옵셋을 추정하기 위한 모의 실험을 통해 상기 세 가지 기법에 의한 OFDM 심볼을 생성하는 단계와; 상기 OFDM 심볼을 ISI 다중경로 채널로 전송하는 단계; 상기 세 가지 기법들의 시간 측도의 값을 연산하고, 소정의 설정된 시간 옵셋 값과 각 기법들을 통해 추정한 시간 옵셋 값과의 차이를 나타내는 평균 제곱 오차(mean square error: MSE) 값을 연산하며, 각 기법들의 평균값을 연산하는 단계 및; 최적의 기법을 선택하기 위해 상기 기법들의 시간 측도의 값을 비교하고, 설정된 시간 옵셋 값을 이용하여 각 기법들을 통해 추정한 시간 옵셋 값과의 차이를 나타내는 평균 제곱 오차(MSE) 값과, 각 기법들의 평균값의 비교를 통해 각 기법의 시간 옵셋 추정 정확도를 비교하여 최적의 기법을 판단하는 단계를 갖추어 이루어진다.