Wireless-Powered Sensor Networks: How to Realize

In this paper, we study a multi-antenna wireless-powered sensor network (WPSN), in which a power beacon wirelessly transfers electric energy to a sensor node via an electromagnetic wave. We have implemented a real-life multi-antenna WPSN testbed and conducted extensive experiments on the testbed. The key technology for the high-efficiency WPSN is an adaptive energy beamforming scheme that dynamically steers a microwave beam towards a sensor node. We propose a receive power-based channel estimation and energy beamforming algorithm. In addition, an adaptive duty cycle control algorithm is proposed to prevent energy storage of a sensor node from being depleted. The proposed duty cycle control algorithm is designed based on a proportional-integral-derivative controller. These algorithms are all implemented in the multi-antenna WPSN testbed. By experiments, we validate the feasibility of the multi-antenna WPSN, and show the performance of the proposed algorithms.