M-ary Code Shift Keying Direct Sequence Spread Spectrum with Gold Sequence Using in Underwater Acoustic Communication

Owing to its anti-noise and anti-fading abilities, spread spectrum communication is widely applied in the underwater acoustic (UWA) field. But the data rate of the Direct Sequence Spread Spectrum (DSSS) is very low, and cannot meet the needs of long-range UWA communication at present. This paper proposes a method, named M-ary CSK-DS, which combines M-ary DSSS schemes with code shift keying (CSK). Gold sequences, as the basic sequences, occupy a fine periodic auto correlation function (PACF), a periodic cross correlation function (PCCF) and a large code set size. This method utilizes sequence information, code phase information, and polarity information. The influence of PACF and PCCF on the proposed method is analyzed over the AWGN and UWA channels. The performance of M-ary CSK-DS is evaluated through simulation over AWGN and UWA channels. The results show that M-ary CSK-DS is superior to the conventional methods. In the last part of this paper, an experiment demonstrates the correctness of the simulation.