The Study Of Energy Saving Strategies In Underwater Wireless Sensor Network

Underwater Wireless Sensor Network (UWSN) is composed of a large numberof sensor nodes with low data rate, which are distributed in the region of interestrandomly to perceive, collect and process the sensing information, and transmit to thedata process center. It has a wide range of applications in offshore exploration andinformation acquisition. Because the sensor nodes are usually powered by thebatteries which are difficult to be replaced in the underwater environment, energyconsumption is one of the most important problems to improve lifetime of UWSN, ithas always been a focus of researchers’ attention. Several energy saving strategies arestudied in this paper.Firstly, based on the analysis of UWSN energy consumption effective factors indifferent protocol layers, and summation of some existing energy saving strategies,the delay and energy consumption factors are analyzed both in hop-by-hopforwarding mode and aggregation transmitting mode in linear topology network. Inorder to avoid the energy cave problem near the SINK, some strategies are proposedby adding backup batteries, using aggregation technology or changing the hop lengthto balance the network energy consumption.Secondly, a centralized schedule scheme was proposed. AP (Access Point)broadcasts beacon signal and estimates the distance and delay between itself andevery sensor node. In physics layer, the transmit power and frequency of nodes arechanged adaptively to decrease energy consumption. In MAC layer, the AP schedulesevery node by considering the delay features of underwater link to avoid collision.Finally, a distributed cross-layer routing protocol is proposed, which can getneighbor nodes’ information by exchanging control packets, and compute the idealoptimal hop distance from each sensor node to SINK. Based on cross-layer designidea, in network layer, the next hop node which is closest to the ideal node will beselected as relay node. In physics layer, different power levels were set according tothe position of neighbor nodes. Simulation results show that the proposed protocol consumes less energy than the FBR and VBF routing protocol.