Wireless power transfer and communication for sensors: dynamic frame-switching (DFS) policy

Wireless sensors are key to machine-to-machine communications and serve as the basis for realizing the Internet of Things. Spectral and energy efficiencies are key parameters that determine the usefulness of a sensor. In this paper, we consider the scenario where both information and power are sent through the same wireless medium to sensors. Each sensor independently decides to switch between information decoding (ID) and energy harvesting (EH), comparing its received signal power with some given thresholds. The objective is to maximize the harvested energy subject to reliably decoding the data. We show that in many practical cases of interest, as the number of data frames (packets) increases, it is asymptotically optimal to use a single-threshold policy, in which the sensor uses ID if the received signal power is less than a fixed threshold, and EH otherwise.