Micro-Modem for Short-Range Underwater Mobile Communication Systems

Recently, there has been great interest in short-range underwater communication for applications such as water pollution monitoring, fish farming, oceanographic data collection, and underwater tactical surveillance based on underwater sensor network systems. Because underwater wireless communication relies primarily on acoustics, the development of acoustic modems has been an important topic that needs to be addressed. Furthermore, for years, underwater biomimetic fish robots have been studied in the area of biomechanics for scientific use and reconnaissance missions. In this article, we describe an underwater mobile communication system where fish robots act as sensor nodes, which is different from the conventional concept of an underwater sensor network that is static. We describe the issues that need to be resolved to provide mobility to a node, and we develop a micro-modem to meet the requirements of a moving node. Experiments conducted with prototypes in both a lake and a river verify that the proposed system provides a new degree of freedom (mobility) and is a viable approach.