Fine timing synchronization using power delay profile for OFDM systems

Timing synchronization is more critical in orthogonal frequency division multiplexing (OFDM) systems than in single carrier systems. In this paper, a timing estimation scheme is derived from maximum likelihood estimation (MLE) using power delay profile. It is implemented using a delay locked loop (DLL) to achieve fine timing synchronization for OFDM systems. With this scheme, the mean-square error of symbol timing estimation is decreased by orders of magnitude when compared to the simple peak-finding scheme in multipath fading channels. This scheme also shows higher tracking accuracy for symbol timing drift caused by the sampling clock frequency offset.