OFDM with steering sinusoids for underwater acoustic communication

摘要

The underwater channel poses various challenges for the wireless information exchange as it offers complex communication design. OFDM, being a best viable solution for high rate and efficient underwater communication scheme, also faces signal degradation problems due to the dynamics nature of Sea. These non-uniform dynamics due to the wind or the platform motion are critical for the acoustic subcarriers (i.e. low frequency and low speed) and may cause inter-carrier interference which results distortion of the entire signal. In order to avoid these erratic distortions, proper tracking of relative change in terms of Doppler factor have to be incorporated in the design. The communication design must be capable enough to track aquatic variations and compensate the effects in an efficient way. In this article, a novel OFDM approach based on steering sinusoids is presented which may be able to trace and rectify the fast oceanic variations incurred with in a symbol length. The steering sinusoids are used to check the dynamic effects imposed by the channel and the recorded variations (either uniform or non-uniform) are further utilized to mitigate the Doppler spread. The algorithm is computationally very efficient and gives low latency period as compare to the two-step approach. The placement of the appended sinusoids among subcarriers is depended upon the measure of relative motion and the level of precise tracking i.e. tradeoff have to be considered. The proposed scheme is analyzed in the MATLAB simulation with self-induced Doppler and Bellhop ray tracing program is also executed to generate static multipath channel models. The simulation results endorsed the efficient performance of the proposed algorithm and suggested for the practical evaluation.