Challenges: Building Scalable and Distributed Underwater Wireless Sensor Networks (UWSNs) for Aquatic Applications

Large-scale Underwater Wireless Sensor Network (UWSN) is a novel networking paradigm to explore the uninhabited and complex oceans. However, the characteristics of UWSNs, such as huge propagation delay, floating node mobility, and limited acoustic link capacity, are significantly different from ground-based wireless sensor networks and existing small scale Underwater Acoustic Networks (UANs). The novel networking paradigm poses inter-disciplinary challenges that will require new technological solutions. In particular, in this technical report we adopt a top-down approach to explore the research challenges in UWSN design. Along the layered protocol stack, we roughly go down from the top application layer to the bottom physical layer. At each layer, a set of new design intricacies are studied. The conclusion is that building scalable and distributed UWSNs is a challenge that must be answered by inter-disciplinary efforts of acoustic communications, signal processing and mobile acoustic network protocol design.