An Overview of On-Demand Wireless Charging as a Promising Energy Replenishment Solution for Future Wireless Rechargeable Sensor Networks

Abstract

The rapid advancement in the emerging technology of wireless power transfer (WPT) has enabled energy-constrained wireless sensor networks (WSNs) to operate perpetually through the mobile charging robot scheduled to recharge the sensors' batteries. In contrast to previous schemes where the mobile charger (MC) is scheduled to periodically visit and recharge every sensor node (SN) in the network irrespective of their energy status, the current trend is using a more efficient recharging scheme called on-demand. In the on-demand recharging scheme, the MC is scheduled to visit and recharge only a few SNs that have forwarded a recharging request after their battery energies lessen below a preset threshold. However, due to the energy consumption dynamicity of WSNs, designing an on-demand wireless recharging scheme is still a challenging research problem. This article explores some of the recent design issues of on-demand wireless recharging scheme and corresponding performance evaluation metrics. Although recently, researchers have proposed many efficient on-demand recharging schemes, there are still some limitations, such as scalability, high MCs' energy consumption, and prolonged SNs' recharging delay, which, if not adequately addressed through research, may limit the network's performance efficiency as well as lifetime.