A time synchronization method for OFDM-based underwater acoustic communication systems

Due to the strong influence of the ambient noise and the time variation of underwater acoustic (UWA) channels with a large Doppler frequency shift, the time synchronization is a challenging issue in UWA-OFDM systems. In addition, the signal bandwidth of UWA communication systems is very limited. Thus, optimizing the bandwidth efficiency of the system is also an important target in designing synchronization methods for UWA communications. For combating the above-mentioned problems as well as to increase the spectrum efficiency of the system, this paper proposes a time synchronization method for OFDM-based underwater acoustic communication systems. Instead of the using preamble, we use only the guard interval (GI) for the time synchronization. Hence, there is no additional redundancy for synchronization that is requested for the proposed method. Experimental and simulation results show that the proposed time synchronization method outperforms some conventional algorithms used for UWA communication systems.