Design and Implementation of a Gateway Buoy for the Underwater-IoT

In this paper, we propose a concept, design, and implementation of a moored buoy, that is equipped with underwater and radio modems, allowing it to function as a gateway between land-based entities and the acoustic underwater network following the ISO/IEC Underwater-IoT architecture. Utilizing buoys as gateways offers the advantage of reduced noise interference, as they are not affected by engine noise that typically disturbs communication from ships. We highlight its performance improvements achieved by using a gateway buoy within an international sea trial with an acoustic network of 11 nodes. Besides the technology concept of a gateway buoy, we also present the routing adaptions made to the network protocol Gossiping in Underwater Mobile Ad-Hoc Networks (GUWMANET). These extensions allow routing between air-bound network participants and the underwater network, and partially routing underwater messages above the surface using multiple gateway buoys. This approach can increase the robustness and reduce the overall delay, due to the significantly faster propagation of electromagnetic waves compared to sound waves.