Robust Timing and Frequency Synchronization for OFDM Systems

This paper deals with timing and frequency synchronization in orthogonal frequency-division multiplexing (OFDM) systems. A robust multistage scheme that works in the time domain, independent of the preamble structure, is proposed. After coarse-timing estimation, joint timing and integer frequency synchronization is performed. Then, fractional frequency correction is carried out, and finally, fine-timing estimation completes the synchronization process. The new timing estimation method is flexible and can be adjusted according to the degree of channel distortion. Furthermore, frequency synchronization is efficiently accomplished with an estimation range that is as large as the bandwidth of the OFDM signal. The performance of the proposed method is evaluated in terms of the mean square error. The results indicate that the new method significantly improves performance compared with the previous methods.