On Wireless Charging for Mobile Sensors

Battery-powered sensor devices have been an essential component in Internet of Things (IoT) applications. Much effort has been devoted to designing algorithms that identify efficient routes for a mobile wireless charger to feed sensor devices with energy without plugs, in which power is wirelessely transferred from the charger to sensors. However, existing studies assume static sensors. In this paper, we address the problem of finding better mobile charger trajectories for mobile sensors, where sensor devices are assumed to be mobile. We first introduce two problems. One is the MaxAC problem that maximizes the amount of charge from a charger to sensors within a given time constraint; the other is the MinCD problem that minimizes the charging delay to provide all the sensors with at least a target power level. To this end, we design the charging utility prediction model to estimate how much power can be transferred during a given time interval. Then, two trajectory planning algorithms are proposed, namely TPA-MaxAC and TPA-MinCD, for each problem. The simulation results demonstrate that the proposed algorithms outperform a baseline algorithm as well as the state-of-the-art wireless charging algorithms.