Timing synchronization in high mobility OFDM systems

OFDM systems are sensitive to timing synchronization errors. Utilizing pilot-aided channel estimators in OFDM systems can further increase this sensitivity. This is shown in Y. Mostofi et al. (Oct. 2002) where authors have analyzed the-effect of such errors on a pilot-aided channel estimator in a fixed wireless environment. They proposed an algorithm that exploits this sensitivity to improve timing synchronization without additional training overhead. The effect of these errors and design of suitable synchronization algorithms for high mobility applications, however, have not been studied before. In this paper we extend the analysis in Y. Mostofi et al. (Oct. 2002) to high mobility environments. Timing synchronization becomes more challenging for mobile applications since power-delay profile of the channel may change-rapidly due to the sporadic birth and death of the channel paths. We find analytical expressions for channel estimation error in the presence of timing synchronization errors and mobility. We show that the sensitivity of the channel estimator can still be exploited to improve timing synchronization in high mobility environments. Then we extend the algorithm proposed in Y. Mostofi et al. (Oct. 2002) to high mobility applications. Finally simulation results show the performance of the algorithm in high delay and Doppler spread environments.