Fast Interference-Aware Scheduling of Multiple Wireless Chargers

Nowadays, breakthroughs in wireless power transfer make it possible to transfer energy over a long distance. Existing works mainly focused on maximizing network lifetime, optimizing charging efficiency, and optimizing charging quality. All these works use a charging model with the linear superposition, which may not be the most accurate in a real life situation. We use a concurrent charging model, which has a nonlinear superposition, and we consider the Fast Charging Scheduling problem (FCS): given multiple chargers and a group of sensor nodes, how can the chargers be optimally scheduled over the time dimension so that the total charging time is minimized and each sensor node has at least energy E? We prove that FCS is NP-complete and propose algorithms to solve the problem in 1D line and 2D plane respectively. Unlike other algorithms, our algorithm does not need to calculate the combined energy of every possible combination of chargers in advance, which greatly reduces the complexity. We obtain a bound in 2D cases when chargers and sensors are uniformly distributed. Extensive simulations demonstrate that the performance of our algorithm is almost as good as the optimal algorithm when the distribution of chargers is not very dense.