The Design And Implementation Of Node Localization Algorithm In Underwater Wireless Sensor Network

With the increasing global attention paid on marine economic development, underwaterwireless sensor networks (UWSN) becomes a new research hotspot. The study of node localizationtechnology is indispensable and node self-localization is the basis to carry out other work.In water environment, node replacement is difficult and means for energy supply are limited,therefore energy conservation for nodes is a key problem remaining to be solved. However, many ofthe locating schemes require precise time synchronization during the ranging process, which resultsin additional communication costs. For those few programs with no need of time synchronization,symmetrical round-trip localization is in demand, however, the goal of energy-saving is still notattainable. In the paper, energy saving is considered as our fundamental starting point. Taking intoaccount the low bandwidth available and large underwater acoustic channel propagation delay,underwater acoustic MODEM will consume considerable power in the process of communicationduring which the energy consumption in transmission process is much larger than that of receivingprocess. Hence, the locating scheme in the paper is designed for the purpose of minimizing thenumber of data exchange. First, a ranging method similar with TOA is used to ensure the locationaccuracy and reduce energy consumption at the same time, then the least squares method isemployed to calculate the three-dimensional coordinates of the node. Next, locating algorithmflowcharts based on a base station, a beacon node and the unknown node are given, respectively.Finally, a simulation model is presented in the paper to evaluate the locating scheme. Numeroussimulation results show that the asymmetrical round-trip locating scheme without timesynchronization proposed in the paper can significantly reduce energy consumption while ensuringlocation precision simultaneously.