Wireless Powered Sensor Networks: Collaborative Energy Beamforming Considering Sensing and Circuit Power Consumption

This letter studies a wireless powered sensor network, in which a number of sensor nodes send common information to a far apart information access point (AP) via distributed beamforming, by using the wireless energy transferred from a set of nearby multi-antenna energy transmitters (ETs). We consider practical sensing and circuit power consumption at sensor nodes, in addition to their transmission power. In this case, each sensor node is activated in information transmission only when its harvested power is larger than the sensing and circuit power. Under this setup, we aim to maximize the received signal-to-noise ratio at the information AP, by jointly optimizing the collaborative energy beamforming at ETs, and the distributed information beamforming and the inactive/active status of sensor nodes, subject to individual power constraints at ETs and sensor nodes. We propose both optimal and suboptimal solutions to this problem based on the exhaustive search and the greedy algorithm for selecting active sensor nodes, respectively.