Robust Synchronization to Frequency Selective Fading Channel in OFDM Systems

The synchronization is one of the most important issues in the OFDM systems. Although the cyclic prefix has widely been used for symbol synchronization, it may not provide performance robust to the multi-cell environment. Therefore, the training symbol method is usually employed in multi-cell environment. Although the use of matched filter can provide best performance, it may have a problem of a large amount of computational complexity. To reduce the complexity, Cox introduced a method that utilizes a training symbol that has two repetitive patterns. However, it may not properly work in frequency selective fading channel due to the delay spread. In this paper, we propose three-step synchronization scheme robust to frequency selective fading channel. Firstly, the receiver obtains frame timing and then the symbol timing in the next step. Finally, the delay is compensated to correct residual timing offset. To facilitate the three-step operation, we design a training symbol that has four repetitions within a symbol period. Numerical results show that the proposed scheme can provide robust performance with low complexity. I