A New Symbol Time Estimator for Orthogonal Frequency Division Multiplexing Systems

In this paper, we propose a new symbol time estimator utilizing a specifically designed pilot symbol for orthogonal frequency division multiplexing systems. The proposed estimator consists of two stages of estimation (coarse-to-fine). In the stage of coarse estimation, the redundant information contained within the cyclic prefix is used for rough symbol time estimation. In the stage of fine estimation, the merit of the designed pilot symbol structure is utilized to generate a fine symbol time estimate. Computer simulation results show that, although the new estimator has a slightly larger variance than a recently described method by Minn et al. for additive white Gaussian noise channels, it has a significantly smaller variance and a smaller bias (i.e., mean of the estimation error) for intersymbol interference channels. The new method also involves less computational complexity than the previous related approaches.