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OFDM system performance is sensitive to frequency offset and timing error than single-carried system. In this paper, a novel joint time and frequency synchronization method is proposed based on PN sequences for OFDM. A special training symbol of OFDM is constructed with the PN sequence and the differentially coded PN sequence in the transmitter, in the receiver, the training symbol is differentially decoded to get the time synchronization with the autocorrelation property of PN sequence before the frequency offset is estimated, then it eliminates the effect of polarity of the received signal with local PN sequence to get the fine frequency offset estimation combined with ML method. The performance of time synchronization is excellent in low SNR, the maximum frequency offset estimation range can be up to one half of overall signal bandwidth, the simulation results show that the proposed method is effective.
Date of Conference: 8-11 Aug. 2009