Fuzzy depth based routing protocol for underwater acoustic wireless sensor networks

Underwater wireless sensor networks consist of a variable number of sensors and vehicles that are implemented to perform collaborative monitoring tasks over a given area. however,designing energy-efficient routing protocols for this type of networks is essential and challenging because the sensor nodes is powered by batteries,underwater environment is harsh and propagation delay is long. most of the existing routing protocols used for underwater wireless sensor networks,such as depth based routing (dbr) protocol use a greedy approach to deliver data packets to the destination sink nodes at the water surface. further,dbr does not require full-dimensional location information of sensor nodes. instead,it needs only local depth information,which can be easily obtained with an inexpensive depth sensor that can be equipped in every underwater sensor node. dbr uses smaller depth as the only metric for choosing a route. this decision might lead to high energy consumption and long end to end delay which will degrade network performance. this paper proposes an improvement of dbr protocol by making routing decisions depend on fuzzy cost based on the residual energy of receiver node in conjunction with the depth difference of receiver node and previous forwarder node and the number of hops traveled by the received packet. our simulation was carried out in aquasim an ns2 based underwater simulator and the evaluation results show that the proposed fuzzy multi metric dbr protocol (fdbr) performs better than the original dbr in terms of average end to end delay,packet delivery ratio and energy saving.