Research On Routing Protocols Of Underwater Wireless Sensor Networks

As a new research field,underwater wireless sensor networks have attracted significant research attention recently. UWSNs have been playing key roles in many applications related to aquatic environment, such as ocean monitoring, offshore oil/gas exploration, seismic monitoring, marine military defense, etc. In fact, with many inherent features, UWSNs are significantly different from the terrestrial sensor networks. The main one is that the UWSNs have to utilize acoustic signal as the transmission media. Due to the significant differences from terrestrial wireless sensor networks, such as slow propagation speed, low available bandwidth, poor link quality and limited energy, designing an efficient routing protocol for the underwater sensor networks is very challenging. Many routing protocols have been proposed to provide an efficient communication in UWSNs. Multi-hop routing protocol is a typical category of these protocols and is being intensively studied.In this paper, a relative distance-based forwarding routing protocol RDBF is devised,which always try to send the packets along an optimized path. The total count of end-to-end hops is least, energy consumption is efficient and delay is shorter. In addition, to limit the scope of candidate forwarders and find the optimal relay, we utilize a fitness factor to measure and judge the degree of appropriateness for a node to forward the packets. The consumption unbalance problem is inevitable when we fix the destination node in a multi-hop routing protocol. The source nodes send data packets to the neighbor nodes of the destination node in a forwarding manner, which leads to the nodes closer to the destination node forward more data packets and consume more energy. Once some nodes close to the destination node die,the communication path is interrupted. To approach this problem, a regional energy level based routing RELB protocol is proposed, which utilizes AUVs as the temporary destination nodes to termly leave for the region with highest energy level to collect data packets.To validate the conclusions, vast of experiments are conducted in the Aqua-Sim based simulator, the results show that RDBF performs better in terms of end-to-end delay, packet delivery ratio and energy efficiency. Beyond that,the RELB can achieve a better performance in energy consumption balance and extend the lifetime of the networks.