Wireless Charging Scheduling for Long-term Utility Optimization

Wireless Power Transmission (WPT) has been widely used to replenish energy for wireless sensor networks, where the energy consumption rate of sensor nodes is usually time-varying and indefinite. However, few works have investigated the problem of long-term charging scheduling with random variable. This paper designs an optimization model for the long-term scheduling of chargers to maximize the time-averaged charging utility while ensuring its time-averaged constraints of budget and response rate. The Lyapunov optimization technique is adopted to transform the stochastic optimization problem into a deterministic optimization problem, which remains NP-hard. Thus, an approximation algorithm following greedy approach is proposed to solve the deterministic optimization problem. We further provide the theoretical analysis of feasibility and performance guarantee of the proposed scheduling algorithm. The simulation results show that our algorithm outperforms three comparison algorithms by 6.53%, 20.04% and 19.97% in terms of time-averaged charging utility, as well as by 11.25%, 4.42% and 3.73% in terms of time-averaged response rate on average.