A robust multihop underwater network for sensing applications — Implementation and experimental evaluation

Various novel applications of underwater acoustic sensor networks have emerged or been proposed in recent years. In this paper, we present a complete system implementation of a robust multihop underwater network for sensing applications. At the core of the system is a robust data delivery scheme which uses opportunistic automatic repeat request (ARQ) with bidirectional overhearing. We demonstrate the modular and hardware-independent nature of our implementation by porting and deploying the software architecture and underwater network stack onto hydroacoustic modems from different vendors. We integrate off-the-shelf GPS receivers and temperature sensors and evaluate the performance of the data delivery scheme by transmitting actual sensor data over two hops in shallow underwater environments in Singapore. Received sensor data are then visualized using Google Earth as they arrive at the sink node.