Research On Charging Scheduling In Rechargeable Wireless Sensor Networks

Wireless charging technology based on magnetic coupling resonance has provided a potential solution to solve the energy problem in wireless sensor networks.In order to guarantee the sustainable operations of networks,it is essential to improve the working efficiency of mobile chargers,balance the distribution of energy and meet the dynamic energy demands of networks.This paper aim to extend the lifetime of wireless sensor network by using the technology of magnetic coupling resonance and the model of resonant repeater transmission,then does research in three relations that are sensor nodes and mobile chargers,sensor nodes and sensor node,mobile chargers and mobile chargers.The main results of this paper are as follows:(1)Charging scheduling strategy of a single mobile charger with limited energy in wireless sensor networks.In order to guarantee the schedulability of multi-node charging technology,reduce the energy consumption of mobile chargers,cellular structure was adopted to divide the network into several charging areas considering the effective charging range of magnetic resonance coupling,and a charging scheduling strategy based on mobile charger is proposed.A self-adaptive dynamic algorithm for automatically selecting k charging areas was raised to comprehensively consider energy of mobile charger,residual energy of nodes and other factors during each charging period.When planning the route,elastic network algorithm with good timeliness was adopted to meet charging demands of sensors.The simulation results show that the energy of mobile charger has direct impact on total energy and minimum residual energy of networks.When energy of mobile charger is limited,the proposed strategy can maximize minimum network energy and extend lifetime of networks.(2)Strategy for multi-hop energy wireless transmissions equipped with resonant repeaters.Aiming at the problem that energy transfer efficiency is limited by the energy transmission radius in one-to-many charging model,a multi-hop energy transmissions strategy,and a nodes energy transmission protocol in charging areas are proposed.In multi-hop energy transmissions strategy,the minimum spanning tree is constructed in every charging area,and the energy transmission path of each node is optimized in turns in order to improve the charging efficiency of mobile chargers.In nodes energy transmission protocol,in order to reduce the regional charging time,the multi-hop energy transmissions strategy is used to transmit the internal charge request when the residual energy of one node reaches the given threshold,realize the energy transmissions between nodes and smooth the remaining energy of networks.The simulation results show that the multi-hop energy transmissions strategy and the nodes energy transmission protocol can reduce the dwell time of mobile chargers and smooth the remaining energy of nodes,the networks are more stable.(3)Partition collaborative charging strategy of multiple mobile chargers.Aiming at the problem that some nodes in wireless sensor networks are in remote regions that beyond the maximum coverage of any single mobile charger,and the excessive use of costly charging equipments which may lead to the problem of high cost of networks,a magnetic coupling resonant technology is used to realize the energy transmission between mobile chargers,and a partition collaborative charging strategy is proposed.In order to minimize the number of mobile chargers,this strategy adopts the method of staying and waiting,divides the network into two parts by the location of the furthest node in the network,the node sets and the charging positions for each mobile charger are designed.Only parts of nodes will be selected by the base station to generate charging path in each charging cycle.The simulation results show that the strategy proposed can reduce the number of mobile chargers and times of wireless energy transfer,while ensuring that all nodes are covered.