Symbol time offset estimation in coherent OFDM systems

Abstract

This paper presents a symbol time offset estimator for coherent OFDM systems. This estimator exploits both the redundancy in the cyclic prefix and the pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the ML estimator for the AWGN channel. Simulations of an example system indicate a system performance as close as 0.3 dB to a perfectly synchronized system. Compared to an estimator not using pilots, our estimator's performance could allow a shorter cyclic prefix and thus a more spectrally efficient system.