Efficient Online Charging Algorithm In Wireless Rechargeable Sensor Networks

In recent years,wireless sensor networks(WRSNs)have great application prospects in the fields of smart medical care,national defense security,traffic monitoring,and smart home.Due to its tremendous economic value and promising development,it has received extensive attention from industry scholars.The limited energy of nodes in wireless sensor networks poses a huge challenge for long-term stable data monitoring.Battery capacity of sensor nodes is one of the dominate factors to affect the lifetime of WRSNs.“Wireless rechargeable sensor network” refers to extend the life cycle of the sensor network in order to solve the energy shortage of the sensor node,it's aim at providing power supply to the sensor node through wireless charging of the mobile charging vehicles.In the wireless rechargeable sensor network,there exist some research hotspots on design of the mobile charging strategy,utilization of mobile charger power and reduction of the overall power consumption.This paper tries to maximize the number of charged sensors in the on-demand WRSNs,with constraints of the moving energy consumption of the mobile charger and total amount of energy supply of the base station.The problem is modeled as a non-linear programming with an online greedy algorithm.The greedy algorithm selects the nearest sensor nodes to charge in the charging period.Moreover,a clustering based online algorithm is designed to better improve the charging performance.The online clustering algorithm uses an MST algorithm which is initially used by on the traveling salesman problem to reduce the moving energy consumption of the in one charging loop inside each cluster.Extensive simulation results demonstrate that the online greedy algorithm and the online clustering algorithm can meet 67% and 76% charging requests of all sensor nodes.This paper also studies the periodic charging scheduling strategy for mobile chargers based on the single-charging vehicle charging in wireless rechargeable sensor network.The strategy enables the mobile chargers to achieve the goal of maximizing partially charging rewards in each charging tour.In order to avoid the sensor nodes shutting down due to exhaustion of power,this paper adopts the method of low residual power high charging reward,for forcing the mobile charger to charge the low-power sensor node preferentially.Since the sensor nodes experience multiple charging in each charging tour,the problem of reducing the number of dead nodes in the networks can be transformed into the problem of maximizing the partially charging reward.In this paper,the mathematical model is established base on the problem model firstly,and then an algorithm is proposed to solve the problem of planning charging path for the mobile charger.Finally,the experimental results show that the proposed algorithm can reduce the number of dead nodes in the network by up to 20%.