An inherently void avoidance routing protocol for underwater sensor networks

The presence of void area in the routing path is perhaps the most challenging issue from the routing protocol perspective in 3D acoustic Under-Water Sensor Networks (UWSN). In this paper, we propose a new routing protocol, called Inherently Void-Avoidance Routing (IVAR), to address the void problem without relying on any positioning system. IVAR is able to efficiently bypass void areas by properly selecting the forwarding nodes using only the local information, i.e. depth and number of hops to the sink. It inherently excludes all the routes leading to a void area and therefore does not need to switch to recovery mode. In dense scenarios, IVAR can deliver packets using a shorter distance compared to other unicast routing protocols. A fitness factor is employed to evaluate the appropriateness of each node for packet forwarding to confine the scope of the forwarding nodes. In sparse networks with many possible void areas, IVAR is also able to find the best, or close to, path, if any, with minimum communication overhead. The results of our extensive simulation study for sparse to dense networks demonstrate that IVAR outperforms other recently proposed protocols in terms of packet delivery ratio, average hop count, and propagation deviation factor.