Blind synchronization scheme using the conjugate characters of the OFDM BPSK-modulated symbol

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• 作者：Cheng-Ying Yang^a ; Gwo-Ruey Lee^a ;   ; ^b ;   ; ^{rayer@tmue.edu.tw} ; Wen-Hui Kuan^b ; Jyh-Horng Wen^c[Author vitae]
• 关键词：OFDM systems ; Symbol synchronization ; Timing estimation ; Conjugate characters ; BPSK modulation
• 刊名：Digital Signal Processing
• 出版年：2011
• 出版时间：December 2011
• 年：2011
• 卷：21
• 期：6
• 页码：710-717
• 全文大小：382 K

文摘

Previously, Beek?s scheme for timing and frequency offset estimation in the OFDM system employs cyclic prefix (CP) has been proposed under the assumption of independent identified distributed (i.i.d.) OFDM symbols. Actually, the real data in the OFDM modulated symbol, transferred by the inverse fast Fourier transform (IFFT), has the characters of complex symmetry. With these characters, more information in the whole OFDM symbol could be used for the timing and frequency offset estimation. In this paper, two conjugate symmetry characters of the OFDM BPSK-modulated symbol are used to achieve blind timing estimation algorithm in the OFDM systems. One is symbol-based symmetry and the other is CP-based symmetry. With these two conjugate characters applied to the proposed algorithm, the timing of the OFDM BPSK-modulated symbol could be derived. Under an AWGN channel, based on the performance of lose symbol timing rate and estimator mean square error, the proposed algorithm is with a tremendous improvement compared with Beek?s estimation method. Under a multipath fading channel, the results show that performance including lose symbol timing rate and estimator MSE with the proposed algorithm is better than those algorithms with Beek?s estimation method. In practical OFDM applied system, the OFDM BPSK-modulated symbol could be used to replace the preamble or training sequences in the standard to obtain an accurate timing and frequency offset estimation and to avoid the data rate decreasing with the proposed algorithm.