Channel Compensation of Variable Symbol Timing Offset in Non-synchronized OFDM System
In this paper, we propose the method of channel compensation with phase rotator (PR) when there is variable symbol timing offset (STO) in non-synchronized orthogonal frequency division multiplexing (OFDM) system. Because the symbol timing of OFDM symbols is estimated within cyclic prefix (CP) interval, a STO occurs and makes the received quadrature amplitude modulation (QAM) symbols rotated. These rotated QAM symbols can be compensated with frequency domain equalizer (FEQ). However, because the drift of symbol timing occurs in non-synchronized OFDM system, symbol timing should be estimated every OFDM symbols. Thus, the STO of the first OFDM symbol can be different from it of other OFDM symbols. PR compensates the phase difference caused by STO differences of OFDM symbols before FEQ. We show that the uncoded-bit error rate (BER) between the synchronized OFDM system and the proposed non-synchronized OFDM system is the same under additive white Gaussian noise (AWGN) and multipath channel.
KeywordsCyclic prefix Symbol timing offset Phase rotator Frequency domain equalizer
This work was supported by the IT R&D program of KCC. [10035709, Development of Next Generation Digital Cable Transmission Technology].
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