A two-stage routing protocol for partitioned underwaterwireless sensor networks

Constraints of the underwater environment pose certain challenges to the design of routing protocols for underwater sensor networks. One such constraint is free mobility of sensor nodes with water currents. Free mobility and asymmetric acoustic propagation characteristics may lead to network partitioning which results in one or more nodes being unable to connect to the rest of the network and thus unable to report their sensed data. In this work, we propose a two-stage routing protocol to enable not only the connected nodes but also the partitioned nodes to successfully report their data thus improving the overall packet delivery ratio. We also introduce a minimum energy threshold and a rerouting scheme to delay death of busier nodes, thereby ensuring that nodes stay alive longer for their sensing job, and to avoid connectivity holes, respectively. Moreover, we also resolve forwarding loops to avoid the unnecessary waste of resources. Our results show that the proposed scheme successfully resolves network partitions and achieves a higher packet delivery ratio while avoiding early death of sensor nodes.