A robust Coarse Symbol Timing Synchronization for OFDM systems in multi-path fading channel

Orthogonal Frequency-Division Multiplexing (OFDM) system is widely used in digital broadcasting systems such as DVB-T and ISDB-T due to its robustness to frequency selective fading channels and a simple equalization scheme [1]. For reliable reception of an OFDM signal, symbol timing and carrier frequency synchronization should be accomplished in advance before channel compensation. Symbol Timing Synchronization (STS) consists of two phases; Coarse Symbol Timing Synchronization (CSTS) and Fine Symbol Timing synchronization (FSTS). CSTS finds the beginning position of a frame and/or OFDM symbols whereas FSTS keeps track of the timing frequency offset. Usually CSTS is accomplished through the correlation operation of an OFDM symbol with its delayed version using the fact that data in the guard interval is identical to the end part of the OFDM symbol [2][3]. The method in [2] performs direct correlation and finds peak position for CSTS. It works well for a weak multi-path channels, but suffers from mal-functioning because of ambiguity caused by ISI effects. Difference based CSTS algorithm in [3] can improve the performances for moderate ISI channels, but it also shows drawback in heavy multi-path fading channels. In this paper, we deal with an alternative CSTS algorithm which is quite insensitive to ISI channels, thereby showing consistent synchronization performances for OFDM