MAC protocols for broadcasting and information retrieval in underwater networks

Underwater acoustic networks of fixed and autonomous nodes can be a very valuable tool in a number of situations, from environmental monitoring to emergency scenarios (e.g., ships in distress). In this paper, we compare the performance of some MAC protocols for underwater networks in typical scenarios. We consider random access protocols, which provide sufficiently high performance in case of low traffic, and then compare random access with handshake-based access, which achieves better coordination among nodes, at the price of greater control overhead. We consider both periodic traffic and event-driven traffic, and provide insight about which scheme achieves the best performance in terms of relevant network metrics such as throughput, error rate and overhead. In our evaluation, we assume the network protocols to work over a low-rate FH-BFSK-based physical layer, a simple technique that can be easily implemented, e.g., to work as a common PHY for different modem hardware.