M-ary cyclic shift keying spread spectrum underwater acoustic communication using frequency domain energy detector

Abstract

M-ary cyclic shift keying (M-CSK) method can greatly improve the communication rate of conventional direct sequence spread spectrum, but the robustness is seriously influenced by the fluctuation of sea surface and Doppler effect. As to this problem, M-ary cyclic shift keying spread spectrum (M-CSKSS) underwater acoustic communication (UAC) based on frequency domain energy detector (FDED) algorithm is proposed in this paper. Time reversal (TR) is firstly adopted to suppress multipath spread using channel impulse response (CIR) estimated from the former symbol. And then the baseband signal after TR processing goes through a FDED, decisions are made according to the output energy later. Simulation results show the robustness of this algorithm under low signal-to-noise ration and multipath environment. In a field experiment, data transmission with very low bit error rate (BER) was achieved and the communication rate was 375bits/s.