Establishment of underwater wireless acoustic MODEM using C-OFDM

Establishing an underwater wireless acoustic communication link for practical applications is still a difficult task because of the severe channel conditions. Doppler and range spread are extremely high for under water channels (UWC) compared to ordinary radio channels. Moreover, the ever varying nature of the UWC increases the uncertainty in predicting the worst case values of doppler spread and range spread. In recent years, orthogonal frequency division multiplexing (OFDM) has emerged as the single solution to most of the problems in wireless communication systems. OFDM has dominated over single carrier modulation techniques mainly because of the simple, robust and low complexity receiver design with high data rate and high band width efficiency. But, it is only very recently that people have started exploring the usage of OFDM for UWC. In this paper, the design, modeling and testing of coded OFDM based underwater acoustic communication system for high data rate applications is explained.