Research On Partial Charging Strategy Of Wireless Rechargeable Sensor Networks

Wireless sensor networks(WSNs)realize the connectivity of the physical world,the computer world and human society through the integration of data collection,processing and fusion.Because WSNs can be deployed in hard to reach or dangerous areas to achieve monitoring tasks,WSNs are widely used in military,agriculture,environment,medical treatment,smart home and other fields.However,the limited energy of sensor node battery restricts the performance and life of the network.Luckily,with the development of wireless power transfer(WPT)technology,Wireless rechargeable sensor networks(WRSNs)use wireless charging robot(WCR)to supplement power to sensor nodes,making it possible for the network to operate for a long time.At the same time,how to effectively schedule WCR to supplement the energy of sensor nodes is a hot research field.Aiming at the problems of energy consumption difference and low efficiency of full charging in heterogeneous networks,this thesis designs a partial charging strategy of WRSNs based on node priority,which effectively reduces the mortality of sensor nodes.Aiming at the problems of random events destroying the network energy balance and the side effects of partial charging,a pre-charging strategy of WRSNs based on Markov chain is designed,which improves the charging efficiency of WCR and the working performance of the network.The specific work can be summarized as follows:(1)Most of the current WRSNs charging algorithms do not consider the dynamics and differences of energy consumption of sensor nodes,and ignore the charging requests of some sensor nodes,which cause the corresponding algorithms are not suitable for the widely existing heterogeneous WRSNs.To deal with that problem,this thesis proposes a node classification strategy(NCS).Firstly,according to the amount of communication data and corresponding energy consumption of sensor nodes,the energy consumption rate model of sensor nodes is established.Then the node priority is determined by combining the energy consumption rate and spatial distance information of sensor nodes,so as to improve the fairness of charging response.At the same time,most charging algorithms supplement the battery power to the maximum by default,resulting in a limited and small number of charged sensor nodes.This thesis designs a partial charging algorithm(PCA)based on NCS to optimize the charging value of sensor nodes,which not only ensures the power consumption of sensor nodes,but also allows the limited power of WCR to be reasonably distributed to more sensor nodes with energy demand.Finally,Matlab simulation experiments show that the proposed charging algorithm NCPCA(node classification partial charging algorithm)can effectively reduce the mortality of sensor nodes in the network and improve the performance of WRSNs.(2)In view of the damage to the network energy distribution caused by emergencies,the uneven distribution of energy consumption in heterogeneous networks,and the frequent charging requests and distance overhead caused by partial charging,this thesis first introduces the Markov chain energy prediction algorithm(MCEP)to obtain the predicted total energy consumption rate and predicted residual energy of sensor nodes.Then search the sensor nodes with pre-charging demand in the network to avoid the death of the sensor nodes that have not sent the charging request in the future under the condition of high energy consumption.At the same time,in order to reduce the distance overhead of WCR,a dwell position finding algorithm(DPF)is designed to plan the optimal dwell position and charging path of the sensor nodes to be charged and precharged.In order to optimize the energy utilization of WCR,a pre-charging loss minimization algorithm(PLM)is designed to find the minimum value of the cumulative cost function to maximize the pre-charging benefit.Simulation results show that the proposed pre-charging algorithm(PA)not only reduces the mortality of network sensor nodes,but also effectively reduces the average charging waiting time of sensor nodes,improves the energy utilization efficiency of WCR,and significantly prolongs the life cycle of WRSNs.