A hybrid routing protocol for underwater acoustic networks

This paper presents a new packet-forwarding mech-anism for underwater acoustic networks. The solution, termed MPR-Light, combines the modus operandi of the Multi-Point Relay (MPR) protocol and of the Enhanced Flooding (EFlood), both described in [1]. MPR-Light aims at providing the ro-bustness of a flooding solution in the presence of unreliable and asymmetric acoustic links, while reducing the network load and energy consumption at each node. No periodic control messages are transmitted by each data source or relay nodes. Any additional control data used to find the best relay towards the final destination is appended to regular data packets. Similarly to MPR, relay nodes are selected according to (recent) historical information considering different metrics, i.e. link quality, link liveliness and symmetry. When no information is available at a node, the EFlood approach is used. The performance of MPR-Light has been compared with that of MPR and EFlood during the CommsNet13 sea trial, organised by the NATO Centre for Maritime Research and Experimentation (CMRE) and conducted off the coast of the Palmaria island (La Spezia, Italy) in September 2013. A heterogeneous network of 12 nodes was deployed. Our results show that MPR-Light, using an hybrid strategy, is able to significantly reduce the overhead and energy consumption in the network while maintaining similar or better performance in terms of packet delivery ratio and end-to-end latency with respect to MPR and EFlood.