Research On Scheduling Algorithms Of Mobile Chargers In WRSN

With the rapid development of system on chip(SOC),micro-electro-mechanical-systems(MEMS)and embedded technology,wireless network technology has become a major pillar in information technology field.In modern information society,wireless sensor networks(WSNs)is of great use in data acquisition.In the traditional WSNs,limited battery capacity of sensor has become key factor that affect lifetime and reliability of sensor networks.Wireless rechargeable sensor networks(WRSNs)has attracted wide attention due to the advancement in wireless energy transfer technology in recent years.In WRSNs,mobile chargers are used to replenish energy for sensor nodes.This paper studies scheduling algorithms for mobile charger to charge sensors in WRSNs,and presents a model of wireless rechargeable sensor network and path planning algorithm for mobile charger.The lifetime of sensors in wrsn is improved.We first established a model for mobile charger to charge nodes in sensor networks with an objective of minimum the failure rate of sensors,subject to limited battery capacity of mobile charger and waiting time of to-be-charged sensors.According to the model proposed,we designed offline and online algorithms for offline and online mode severally.Finally,we conduct extensive experiments by simulation to evaluate the performance of our algorithms,compare node failure rate in different network sizes and analyse the influence of mobile charger energy budget to node failure rate.Experimental simulation shows that,the node failure rate of offline mode is 5% lower than that of the online mode and upper limit of battery capacity in mobile charger has great impact of node failure rate when number of sensors in WRSNs reaches a certain size.Simulation also shows that alogrithms can achieve better performance if we set energy threshold of sensor at 30% of its own battery capacity.Besides,with a large scale WRSNs environment,scheduling algorithms for multiple mobile chargers are also studied.We first apply clustering algorithm on the network,then plan path individually in each clusert.Locations,number of neighbours and battery remaining capacity of sensors are considered to decide the charging priority of sensor during path planning.With the joint work of multiple mobile chargers,the total charging time of the network is decreased and the lifetime of sensor network is prolonged.We conducted experiments on scheduling algorithm of multiple chargers and results show that the proposed algorithm can effectively decrease node failure rate in network.