M-ary CDMA multiuser underwater acoustic communication and its experimental results

A novel M-ary code division multiple access (M-ary CDMA) underwater acoustic communication (UAC) that utilizes quasi-orthogonal sequences has been proposed for the multiple mobile unmanned underwater vehicle (UUV). Its performance has been verified in both four-user synchronous and three-user asynchronous scenarios through a lake experiment over a very shallow-water channel. At a chip rate of 2 kilochips per second, good bandwidth efficiency and robust links have been achieved both at 5 and 15 km distances. The performance of M-ary CDMA in mobile condition (3 m/s) is demonstrated by using the recorded lake experimental data. Experimental results show that the proposed scheme is suitable for multi-user communication platform in long-range shallow-water channel with simple receiver algorithms.