LAUSR

This paper considers radio frequency energy harvesting wireless sensor networks where in each period multiple mobile chargers (MCs) simultaneously move along their respective fixed trajectories in the network area to wirelessly charge each sensor node's energy storage above a threshold. We aim to minimize the maximum moving time (i.e., charging completion time) of MCs consumed for passing through their respective trajectories via well-refined MCs’ velocity control. First, we transform this nonconvex and intractable velocity-control problem into a tractable one by discretizing these trajectories into segments and applying the charging power approximation strategy. Then we propose an efficient distributed algorithm to obtain the approximately optimal solution with the approximation ratio $(1+\epsilon)$. Simulation results demonstrate that our proposed velocity-control scheme can reduce the charging time by around 40% as compared with the baseline scheme using a constant speed.