3-D Heterogeneous Wireless Charger Empowered Wireless Rechargeable Sensor Network

Owing to the rise of wireless power transfer technology, wireless rechargeable sensor network (WRSN) becomes a hot research topic in recent years. Compared to traditional wired sensor networks, WRSNs have no cable constraints. Numerous existing studies assume wireless sensors and chargers co-exist in a two-dimensional (2-D) space. In real-world scenarios, however, three-dimensional (3-D) networks account for the majority, making these previous research results difficult to implement. In this paper, we consider a 3-D WRSN with heterogeneous wireless chargers (i.e., the wireless charging vehicle (WCV), the unmanned aerial vehicle (UAV) and the charging base station (BS)) to efficiently power the WRSN. To reduce energy cost, we use green energy to power the chargers. To extend the lifespan of a WRSN, we aim to fully charge as many sensor nodes as possible to minimize the sleep time of all the sensor nodes. As this sleep time minimization problem is NP-hard, we further propose a 3-D hEterogeneous chArger scheduLing (3DEAL) algorithm to efficiently dispatch wireless chargers to prolong the lifetimes of the sensor nodes. In this algorithm, charging tasks are assigned to each charger according to the residual energy of each sensor node, which greatly improves charging efficiency by wisely determining each sensor node’s charging time. Finally, we demonstrate the advantages of the proposed algorithm through extensive experimental simulations.