Design and implementation of acoustic modem for shallow water network

In the South China Sea, an underwater acoustic communication network (UWACN) is now in the experimental phase. The aim of UWACN project is to build a shallow water network which includes more than 10 nodes and continuously collects ocean observation real-time data with duration larger than one month. The design and implementation of robust and low power modem for the underwater network is considered. For the noncoherent modulation, the concatenation code of nonbinary constant-weight codes and convolutional codes are utilized. For the coherent modulation, turbo codes and phase-shifting keying (PSK) are used for each frame, and the Reed-Solomon code are encoded among all the frames in one packet to correct the frame errors. The experimental results are shown in the paper, and further perspective is also introduced.