Research On Coverage Optimization Algorithms Based On Voronoi Diagram In Software-defined Sensor Networks

The subject of the thesis is supported by the National Natural Science Fund(No.61471164),which is named Research on Algorithms of Network Reconfiguration of Software-Defined Sensor Networks.The main work is to study the coverage optimization problem of Software-Defined Sensor Networks(SDSN),and proposes two coverage optimization algorithms based on Voronoi diagram and residual energy of nodes.For the coverage optimization algorithm based on Voronoi diagram,Minimax Radius Algorithm(MRA)is designed firstly,and the nodes' sensing radius are reduced as much as possible while preserving the original coverage of the network.Secondly,SLeeping-based Algorithm(SLA)is designed,we try to set as many nodes as possible into sleep mode without generating new coverage holes.Then,combined with the characteristics of both MRA and SLA,Minimax radius and Sleeping-based Algorithm(MSA)and Sleeping-based and Minimax radius Algorithm(SMA)are designed to reduce nodes'sensing radius and sleep as many nodes as possible.For the coverage optimization algorithm based on residual energy of the nodes,an optimization distribution method of the radius based on the residual energy of the nodes is designed using Delaunay triangulation.The energy distribution of the network is balanced while preserving the full coverage of the target area.Finally,the two algorithms are analyzed by the simulation tool.Simulation results show that both algorithms can reduce the energy consumption significantly and the energy reduction rate increases with the number of nodes.The thesis is divided into five chapters as follows.In Chapter 1,the background and the present status of development in the world are introduced,the significance and purpose of the research are clarified.The main work and the specific arrangement of each chapter are described.In Chapter 2,the concept and characteristics of Wireless Sensor Networks(WSN)are introduced firstly.The concept of Software-Defined Networks(SDN),the architecture and controller of SDN are introduced briefly.The working principle of OpenFlow is clarified.The concept of SDSN is introduced combining with WSN and SDN.Finally,other related applications of SDN are briefly introduced.In Chapter 3,MRA,SLA,MSA and SMA are designed based on SDSN according to the concept of Voronoi diagram in geometry.While preserving the full coverage of the target area,the energy consumption of the network is reduced and the simulation tool is used to verify the effectiveness of the algorithms.In Chapter 4,the concept of Delaunay triangulation is introduced into the coverage optimization algorithm based on SDSN according to the different residual energy of nodes.The optimal distribution method of nodes' sensing radius is calculated and the effectiveness of the method is analyzed by simulation tool.In Chapter 5,the research work of this thesis is summarized,and the prospects of future research work are given.