Research On Charging Strategy Of Wireless Rechargeable Sensor Network

Wireless sensor networks(WSNs),which are one of the key technologies of Internet of Things(IoT),have a key obstruction of limited sensor node battery capacity.Wireless power transfer(WPT),which is a promotion of wireless rechargeable sensor networks(WRSNs),is a key solution to the energy problem of WSNs.In WRSNs,vehicles or robots with large capacity of batteries charge the sensor nodes periodically with appropriate charging strategies which contain the determination of quantity,path planning and collaboration of the chargers.In recent years,researchers have presented some charging strategies.However,the strategies in smallscale networks take little consideration of the difference of sensor node positions,and those in large-scale networks focus little on improving the utilization of chargers.In this dissertation,two charging strategies are proposed to handle different kinds of WRSNs,which are summarized as follows:1)A Charging Strategy based on Matroids(CSM)is presented for small-scale WRSNs with uneven energy consumption.A maximum tolerable charging delay for every sensor node that requires charging according to its remaining energy,request time and energy consumption rate is computed and updated by CSM.Then,the charging scheduling problem as a unit time task scheduling problem is modelled by CSM,which builds a matroid model and solve it by a greedy policy in order to ensure the priorities of nodes with heavy load.The simulation result shows that CSM reduces the failure rate of sensor nodes effectively.2)A Sector-Based Collaborative Charging Strategy(SCCS)is proposed for large-scale WRSNs with even energy consumption.The area is divided into sectors whose number is determined according to the maximum charging period of sensor nodes and limitation of charging vehicles in SCCS.Furthermore,SCCS uses a novel collaborative mechanism for charging vehicles.SCCS effectively reduces the requiring number of charging vehicles by increasing the usage rate,planning the rendezvous of charging vehicles and collaborate the vehicles.SCCS has less complexity and higher extendibility compared with other methods,which is indicated by the simulation result.