Charging Strategy Based On Firefly Algorithm In Wireless Rechargeable Sensor Networks

Wireless sensor networks have become one of the technologies that have great influence on the development of modern science and technology in the 21 st century,due to its advantages of reliable communication and easy deployment.With the rapid development of wireless power transfer technology,the research on wireless rechargeable sensor networks has begun.To a certain extent,this technology alleviates the limitations caused by the energy limitation of wireless sensor networks and has great development potential.Wireless sensor networks can be divided into planar type and hierarchical type.In the planar networks,each node sends data to the base station through network route.While in the hierarchical networks,nodes are organized into clusters.The cluster-head nodes send data to the base station after data fusion,which relatively reduces the energy consumption in the networks.Therefore,this thesis mainly studies the charging strategy planning of wireless charging equipment and the clustering protocol of networks.The main research contents are as follows:For the charging strategy of wireless rechargeable sensor networks,a charging strategy JCDRE(Jointly Consider Distance and Residual Energy)based on firefly algorithm is proposed,which jointly considering both temporal and spatial factors.Specifically,the realtime residual energy of the sensor node and the dynamic distance between the sensor node and the wireless charging equipment are considered jointly.Plan the charging path and time slot for the wireless charging equipment.This is different from offline periodic recharge and meets the dynamic application requirements better.And set the endangered level for the each endangered node.For the endangered nodes,the residual energy and the distance to the wireless charging equipment are respectively taken as the two attractive components of the firefly algorithm.The wireless charging equipment always selects the endangered node with the greatest attraction for charging.And dynamic charging time slot is also set.Compared with FCFS(First Come First Serve)and NJNP(Nearest Job Next with Preemption),the simulation results show that the proposed algorithm JCDRE has outstanding advantages in network life cycle,data collection volume,charging delay and other aspects.In the clustering stage of wireless rechargeable sensor networks,a dynamic clustering algorithm is proposed,which is beneficial to networks energy balance.First,the optimal number of cluster heads was obtained by Silhouette Coefficient Method.Two thresholds were set in the preliminary clustering stage,in order to the candidate cluster head have certain advantages in the remaining energy in this cluster,the distance between the candidate cluster head and the node in this cluster and base station.In order to balance the node energy in the cluster head region,the cluster size of each region was dynamically adjusted.Make the size of the cluster closer to the base station larger than the size of cluster farther away from the base station to a certain extent.In order to balance the energy of nodes in the whole network,the energy variance threshold is set to analyze the energy status of the whole network.And the cluster head nodes are replaced periodically.Finally,the firefly algorithm is used to plan the charging time slot and charging path of the wireless charging equipment for the endangered nodes.Finally,compared with the benchmark scheme,the proposed scheme ensures the energy balance of nodes and prolongs the network life cycle to a certain extent.