LOARP: A Low Overhead Routing Protocol for Underwater Acoustic Sensor Networks

Abstract — Underwater wireless communications among un-derwater sensor nodes enable a large number of scien-tific, environmental and military applications. For example, autonomous underwater vehicles will enable exploration of deep sea resources and gathering of scientific data for collaborative missions. In order to make underwater applications possible, real-time communication protocols among underwater devices must be enabled. Because of the high attenuation and scattering effect of radio and optical waves, respectively, these underwater devices are based on acoustic wireless technology. The unique characteristics of underwater acoustic channel- such as distance-dependent limited bandwidth and high propagation delays, require new, efficient and reliable communication protocols over multiple hops to network multiple devices which may be either static or mobile. This paper proposes a new low overhead ad hoc routing protocol designed for underwater acoustic sensor network. The protocol performs route discovery when needed in an on-demand manner. It also characterises a route maintenance phase which tries to recover a failed route. Detection of route failure can generate a lot of routing traffic. The proposed protocol tries to minimize this routing traffic by detecting failure in a more intelligent way either by monitoring network data traffic (if present) or generating lazy acknowledgements (if necessary). Reducing routing traffic minimizes the chance of packet collisions which in turn increases data packet delivery ratio. The performance of the proposed protocol is measured in terms of network throughput, packet delivery ratio, average end-to-end delay and control overhead. The results are compared to those obtained using similar on-demand routing protocols. Simulation results show that the reduction of routing traffic can improve the performance of the network