Cyclic shift spread spectrum code division multiple access underwater acoustic communication based on interference cancellation

Code division multiple access (CDMA) underwater acoustic communication (UWC) can make multiple users communicate with the same channel resources at the same time by using the excellent correlation characteristics of spread spectrum sequences, which can significantly improve the efficiency of underwater acoustic communication network. However, the signal from a nearby user often creates a strong interference for the signal from a distant user in a CDMA communication network, which is known as the near-far problem. As power control is difficult to be applied in UWC networks, this paper proposes to use coordinate zeroing interference cancellation algorithm to suppress strong interference to solve the near-far problem, and make full use of the spatial differences of different user channels to further reduce multiple access interference (MAI). On this basis, cyclic shift spread spectrum (CSSS) coding is used to replace the traditional direct sequence spread spectrum (DSSS) coding, which significantly improves the efficiency of CDMA UWC system. At sea data show that under the condition of obvious near-far problem, 6-user low bit error rate UWC can be realized.