PLPR: Joint Perpetual Lifetime and Path Reduction for Energy Recharging Using Multiple Mobile Chargers in WRSNs

Energy recharging is one of the most important issues in wireless rechargeable sensor networks (WRSNs). Many energy recharging algorithms have been proposed using multiple mobile chargers (MCs). However, the number of MCs that significantly impact the network lifetime of the given WRSNs still can be improved. This article proposes an energy recharging algorithm, called joint perpetual lifetime and path reduction algorithm (PLPR), which uses the MC to recharge the sensors and uses the super MC to recharge the MCs, aiming at minimizing the number of MCs and super MCs while achieving the purpose of sustainable survival of all sensors. Initially, the proposed PLPR determines the number of MCs, clusters the sensors into several groups, and constructs the initial path for each MC in each cluster. Based on these paths, the proposed PLPR further reduces the path length in each cluster and improves the recharging efficiency of the MC. To satisfy the perpetual lifetime of the MCs, the PLPR further constructs an initial path, reduces the path length, and schedules the recharging task of super MCs. Performance evaluations reveal that the proposed PLPR outperforms existing energy recharging algorithms in terms of average energy consumption, total recharging time, charging efficiency, traveling distance of MC, fairness indices, standard deviation (SD) of recharging efficiency, and average waiting time for a given WRSN.