Superimposed DSSS transmission based on cyclic shift keying in underwater acoustic communication

Direct sequence spread spectrum (DSSS) transmission employs a chipping code to spread the transmission over a wider frequency band than it would normally occupy. However, since DSSS signals for underwater acoustic communication have a low transmission rate, they are disadvantaged in the short coherence time of underwater acoustic communication. In this study, we propose a superimposed DSSS that can compensate for the disadvantage of the low data rate of the existing DSSS transmission. A lake trial is performed to verify the performance of the proposed method. Experimental results show that the bit error rate of the proposed method is reduced by up to 0.03.