| In recent years,Wireless Sensor Network(WSN)has been widely used because of its flexible structure,powerful detection function,and strong environmental adaptability.WSN can play its role only when the target is in the detection coverage range of the sensor,so the coverage problem is a fundamental problem of WSN,and its research has important theoretical significance and practical value.Barrier coverage can detect targets passing through the monitored area with high cost-effectiveness,which makes barrier coverage play a key role in fields such as homeland defense and area monitoring.With the development of radar technology,multistatic radar can be exploited to build barrier coverage due to its excellent detection performance and flexible composition.However,the transmitter and receiver of the multistatic radar are located in different positions,the Cassini curve determines the coverage model,and the two foci are located at the receiver and the transmitter,respectively.The Cassini curve makes the multistatic radar-based barrier coverage problem more complex and challenging.This dissertation explores and studies the multistatic radar barrier coverage problem under different scenarios and conditions.The main work includes the following aspects:1.For varied application scenarios,multistatic radar barrier coverage requires different deployment patterns,resulting in different deployment optimization problems.From the perspective of mathematics,this dissertation first summarizes the commonality and consistency of these deployment patterns in the form of theorems,which proves the properties of the deployment patterns and the composition features of the optimal coverage sequence.The research has laid a theoretical foundation for multistatic radar barrier coverage.2.Aiming at the line barrier coverage problems of multistatic radar in different scenarios,the coverage properties of the line deployment pattern and the arc deployment pattern are proved from the length and angle of the barrier coverage.Based on these,the structural characteristics of the optimal coverage sequence of straight line barrier,arc barrier and circular barrier are proposed.Furthermore,the corresponding deployment optimization model is established.For the deployment optimization model of the line barrier without the restricted area,an optimization algorithm combining exhaustive method and Integer Linear Programming(ILP)is used to determine the minimum deployment placement cost and the optimal coverage sequence.By contrast,a two-stage optimization algorithm for the straight line barrier with the restricated area is proposed for the deployment restricted optimization model.In the first stage of the algorithm,the barrier is divided into two segments by a point,and the optimal coverage sequence of each segment is determined respectively.The second stage traverses all possible segmentation points to determine the optimal coverage sequence for the entire barrier.The simulation results and analysis show that the proposed algorithm can effectively solve the deployment optimization problem for the line barrier coverage.3.The line barrier may have zero coverage width at some points,making it challenging to detect high-speed targets passing through the barrier.For this reason,this dissertation studies the optimization problem of the multistatic radar for rectangular barrier coverage.It proposes a one-dimensional deployment optimization method based on width equipartition.The method divides the entire rectangular barrier into several sub-barrier with equal width,and each sub-barrier has the same coverage sequence.Then ILP is adopted to determine the optimal coverage sequence for the sub-barrier.In addition,to further take advantage of the flexible structure of multistatic radar,a one-dimensional deployment optimization method based on unequipartition width is proposed.This method divides the entire rectangular barrier into sub-barrier with different widths.The sub-barrier width is determined by the property of the cost function of the optimal coverage sequence.With the criterion of minimum deployment cost,the optimal coverage sequence and its quantity are determined by ILP.However,the one-dimensional deployment method only uses the receivers and transmitters on the same deployment line.To further improve the cost-effectiveness of the deployment pattern,this dissertation introduces a 2-dimensional deployment optimization method.The method uses transmitters and receivers on the same and adjacent deployment lines to construct barrier coverage.Then an optimization model is established on the characteristics of the 2-dimensional deployment pattern.The enumeration method is used to solve the optimization model to determine the minimum deployment cost and the optimal deployment.The simulation experiments show that from the cost of deploying stations and the number of transmitters,the results of 2-dimensional station deployment are the best,followed by the one-dimensional unequipartition width deployment method.The one-dimensional equipartition width method has the simplest structure,but the results are inferior.4.Aiming at the deployment optimization problem for the circular barrier coverage,the characteristics of deployment patterns are analyzed.The deployment optimization model is established using the width equipartition and unequipartition strategies,respectively.The entire circle area consists of multiple sub-circles with the same width and varied radii in the equipartition strategy.ILP is used to determine the optimal coverage sequence for each sub-circle barrier.By finding the minimum deployment cost,the corresponding optimal coverage sequences are determined.On the other hand,not all the sub-circles have the same widths in the situation of unequipartition width.A deployment optimization algorithm based on hybrid particle swarm optimization is proposed to determine the minimum deployment cost and every optimal coverage sequence.Simulation experiments show that the circle barrier unequipartition deployment method is better than the equipartition one regarding cost and the number of transmitters.5.Considering a restricted area in the practical application,an optimization method for building a rectangular barrier with heterogeneous multistatic radar is proposed.The coverage properties of the heterogeneous multistatic radar deployment pattern are proposed by analyzing the influence of different transmitters on the coverage length.Furthermore,a deployment optimization model of heterogeneous multistatic radar is established via equipartition and unequipartition division strategy.Specifically,in the unequipartition strategy,step-fixed segmentation and chaotic Tent mapping are proposed to determine the sub-barrier width,respectively.After the sub-barrier width is determined,a two-stage optimization algorithm is used to determine the optimal coverage result.Simulation experiments verify the feasibility and effectiveness of the proposed method.Compared with the equipartition strategy,the unequipartition strategy consumes less deployment cost and fewer transmitters.6.The robustness of multistatic radar belt barrier coverage is studied and analyzed.A method to measure the robustness of belt barrier coverage from the perspective of fault tolerance is proposed.The judgment conditions that receivers can sleep at the same time in the rectangular and circular deployment patterns are respectively proved,and an algorithm is proposed to calculate the fault tolerance of the entire barrier.Simulation experiments and analysis indicate that the proposed methods have higher fault tolerance and better robustness of barrier coverage than existing methods. |
