High-speed underwater acoustic communication based on OFDM

Due to multipath propagation and frequency selective fading, there are many obstacles for reliable and high data rate underwater acoustic (UWA) communication. OFDM is an attractive technique beginning used in UWA communication with three obvious advantages: good performance against multipath interference, ability to combat the frequency selective fading and the high frequency band efficiency. Recently, the researches of Refs. 1, 2, 3, 4, 5 focus on short-range UWA communication. In this paper, we pay attention to medium-range (10 km) UWA communication based on OFDM. An OFDM system is designed and realized. Several important problems are described in which the characteristics of UWA channel is analyzed, Doppler frequency shift is estimated by using cyclic prefix and compensated by resampling the received signal. Experiments in a lake were conducted and its performance is investigated. Experimental results show that the data rate reach 9 kbps and 2.8 kbps at a distance of 5 km and 10 km respectively with the bit error rate (BER) below 10/sup -4/.