Sustaining a perpetual wireless sensor network by multiple on-demand mobile wireless chargers

Wireless sensor networks are traditionally constrained by finite energy supply. Recent wireless charging technology enables possibility for timely replenishing consumed energy of dispersed sensors. This paper investigates on-demand wireless charging problem with multiple mobile chargers, which can sustain a large-scale wireless sensor network operation perpetually without knowing energy consumption information of sensors a priori. We evaluate the nearest-first and recent-rarest-first strategies, which schedule multiple chargers for incoming charging requests. Also four synthesized occurrence processes of charging requests are presented and then used to compare scheduling strategies in terms of concurrent charging load and serving latency. Simulation results show that the nearest-first scheduling strategy suits for uniform charging request occurrence processes, while the recent-rarest-first scheduling strategy is better for localized charging request occurrence processes.