Applicability of Routing Protocol for Low-Power and Lossy Networks (RPL) in Underwater Mesh Networks

Automated seawater sample collection and analysis would improve public awareness of unsafe ocean conditions. Such a system could be implemented via a distributed undersea sensor network. Unfortunately, implementation is complicated by the limited bandwidth and high latency of the acoustic communications, typically used undersea. Rapid discovery of network links and nodes is a key function of network routing protocols, greatly reducing the workload needed for network deployment. Most widely used routing protocols depend on periodic Link State Advertisements (LSAs), but these messages can saturate acoustic channels. Routing Protocol for Low-Power and Lossy Networks (RPL) was intended for use in Internet of Things applications, but its design avoids use of periodic LSAs. Rather, as long as topology remains consistent, under RPL, network upkeep messages are sent with exponentially increasing back-off time, resulting in a much more clear channel. This design makes RPL a viable routing protocol for use in the acoustic underwater environment. To demonstrate, RPL was used as routing protocol within a variety of simulated underwater mesh networks. A notional application was developed to send data typical of such a distributed sensor network across the network. Findings from this work that might allow accelerated deployment of a seawater monitoring system are presented in this paper.