A new data rotation syncrhonization scheme for CP based OFDM systems

Abstract

In this thesis, we present a new data rotation scheme for symbol timing and carrier frequency offset (CFO) estimation of orthogonal frequency-division multiplexing (OFDM) systems. We first analyze Beeka??s cyclic prefix (CP) based joint ML estimator [2] and find that its performance can be improved when the average energy of the CP increases. We then propose a new data rotation scheme, where we intentionally introduce a cyclic shift after the inverse fast Fourier transform (IFFT) in the transmitter, to obtain a higher energy CP. This cyclic shift will not impair the orthogonality among the subcarriers and its recovery can be combined with channel estimation in the receiver. We analyze the performance of the new data rotation scheme by using order statistics theory. Our results shows that the new scheme can provide a 1.6dB gain in the performance of the frequency offset estimator and a 6dB gain for the timing estimator at 15dB SNR.