Barrier Coverage Of Wireless Sensor Networks

Wireless sensor networks(WSN),as an ongoing techology of collecting and operating environmental information,has been one of challenges in the 21st Century.The coverage problem,as one of the special fundamental problems in wireless sensor networks,will be studied in our thesis.We study the question of how to search the weaks in WSN,i.e.how to design the object's locomotion trajectory.It is known that such a trajectory is able to guide the people to improve and expand coverage performance by adding the sensors into WSN.The topic of this thesis is a sub-task of the National High-Tech Research and Development Plan of China("863"),and has a theoretical and applied meaning.Our thesis will accomplish the following original works:Firstly,based on the fundamental concept and theory related with the coverage problem, we present a new sensing model called the Discerning Sensor Model(DSM).Using the square of distance,DSM shows the down trend of sensing ability with the increasing distance. Also we analyze two methods(SNS & SNE) on the issue of how many sensors should be deployed to ensure the full coverage for a given area.We find that the number of sensor for full coverage is so large that the practical application can not be realized.The work may be conducted to search and fill the coverage holes in order to improve the performance of coverage.Accessing the the Voronoi diagram and exposure,we demonstrate the measurable relationship between Voronoi and the minimal exposure trajectory.Furthermore,the minimal exposure trajectories are classified as two types.In addition,we discusse the sensitivity and accuracy for each type of trajectory on the situation that the topology is various.Our thesis present a novel localized method for analyzing the distribution of sensing force—the Coverage Force Algorithm(CFA),which fits to the homogeneous and heterogeneous Wireless Sensor Networks.Depending on sensors' own abilities in WSNs,CFA can obtain the distribution of sensing force.Then,the General Voronoi(GV) diagram will be followed.Fortunately,the problems of analyzing coverage performance and building locomotion trajectory in heterogeneous Wireless Sensor Networks,can be solved on the basis of the GV.Theoretical analysis and simulations show that the GV is localized,general,and applied.We propose a heuristic algorithm,namely the SS(Security & Speed) algorithm,to depict such a trajectory that takes into consideration both security and speed.Our proposed algorithm does not require any global topology information,yet shows the better and adjustable tradeoff between trajectory security and speed when the value ofα/βis known.Consequently, SS-algorithm is a localized algorithm.Furthermore,the SS-algorithm works well with the good performance of SS-capacity and stability,and it is not sensitive to the topology and density of sensors.To apply the algorithm,the temporal parameter can effectively restrain the appearance of trajectory flooding.Compared with the approximatively optimal trajectory algorithm(Grid-based),the SS algorithm benefits considerably lower computational load and more practical value.