A Survey on Wireless Power Transfer based Charging Scheduling Schemes in Wireless Rechargeable Sensor Networks

Recently, the wireless sensor networks (WSNs) technology has increasingly become a promising tool for information collection, transmission and processing. Nevertheless, due to the features of sensor nodes such as small size and limited battery capacity, the energy problem has emerged as a foremost bottleneck in WSNs. Fortunately, with the rapid development of wireless power transfer (WPT) technologies and intelligent mobile nodes, the bottleneck can be tackled thoroughly by the battery charging schemes. In this paper, we survey the WPT based wireless rechargeable sensor networks (WRSNs), which utilize the mobile wireless charging vehicles (WCVs) to periodically charge the sensor nodes in WSNs. In WRSNs, the major challenge is minimizing charging costs in order to guarantee a promised lifetime of sensor nodes, which requires an effective analysis of charging factors such as the number, traveling speed, charging range, charging power, traveling path and charging period of WCVs. Hence, we review the latest charging scheduling schemes in WRSNs via classifying and comparing them from five different aspects. Then, we summarize the design pattern of charging scheduling.