Research On Target Location Of Underwater Wireless Sensor Network

With the increasing demand for rich marine resources and the continuous development of marine exploration technology,the Underwater Wireless Sensor Network(UWSN)has an irreplaceable role in the field of marine exploration technology.Underwater Wireless Sensor Network(UWSN)is the key technology for developing ocean observation system,With ocean observing systems,oceanographic data can be collected to monitor environmental pollution,climate change and seabed anomalous activity,UWSN also plays a vital role in the military.Underwater wireless sensor network localization technology is one of the key technologies in the practical application of UWSN.Due to the diversity of underwater environment and the limitations of underwater acoustic information transmission,the existing terrestrial wireless sensor network positioning technology can not be directly used in many cases.Therefore,it is an urgent problem to study the localization algorithm for the underwater three-dimensional environment and to improve the localization accuracy of the nodes.This thesis mainly studied DV-Hop localization algorithm in underwater three-dimensional environment based on the existing node localization algorithms of wireless sensor networks.In addition,we proposed a collinear localization algorithm based on Photogrammetry,designed to reduce the transmission of information between nodes,to reduce energy consumption,to improve the positioning accuracy.The specific research contents are as follows:Aiming at the problem of the DV-hop localization algorithm have a large error in the process of obtaining the average hop distance between unknown nodes,in this thesis,we analyze the influence factors of the node communication radius on the average hop distance,a DV-hop algorithm for hierarchical processing of average hop distance is proposed.First,the algorithm divides all unknown nodes into different levels according to the specific relationship between the average hop distance and the communication radius,so that the unknown nodes of different levels can get the average distance with relatively small error.In the stage of estimating the node position,the algorithm uses the maximum likelihood estimation method based on the lognormal distribution to estimate the unknown node coordinates based on statistical analysis of the node localization error.Aiming at the problem that the ranging technology is difficult to implement andthe network overhead is very large when the unknown nodes require multiple beacon node location information in the localization algorithm of underwater wireless sensor network.In this thesis,we propose a parallel collinear localization algorithm based on Photogrammetry.The algorithm firstly using the vector hydrophone array to gain the signal that carrying the azimuth information of the underwater nodes,then introducing into the bacterial foraging optimization algorithm(BFO)when estimate the direction of arrival(Direction of Arrival)of the source signals with the maximum likelihood estimation.After obtaining the azimuth estimation of the node,the algorithm combines the principle of photogrammetry to solve the coordinates of the unknown node that satisfying the collinearity threshold by judging the collinearity of the unknown node and its surrounding beacon nodes.finally,we Upgrade the unknown nodes to beacon nodes and complete the Positioning process by iterative positioning.