Wireless powered sensor networks

The future Internet of Things (IoT) will connect trillions of devices, where wireless sensors will play an important part. Due to the large scale of such networks, battery replacement is a crucial issue for the massive number of wireless sensors. To efficiently address the finite sensor lifetime problem in IoT, techniques such as energy harvesting powered and wireless power transfer powered WSNs are promising solutions. In this chapter, first, we summarize the state-of-the-art WSNs, EH-based WSNs, and wireless power transfer techniques, and then motivate wireless power transfer-based WSNs. Also we present the major design challenges for wireless power transfer-based status monitoring WSNs, including accurate modeling of sensor energy costs and metrics to take into account the age of the sensed information. We present a novel solution to one of the challenges. Specifically, we present a harvest-then-use protocol and consider two complementary performance metrics to measure the timeliness of the status monitoring WSN, i.e., update cycle and update age. Moreover, we present a framework of analysis for both the update cycle and the update age, which takes into account both the energy cost of sensing and transmission.