Joint Transmission and Energy Transfer Policies for Energy Harvesting Devices with Finite Batteries

TL;DR

This paper investigates how combining energy harvesting and wireless energy transfer can extend the lifetime and improve the performance of energy-constrained wireless sensor networks, providing bounds and optimization strategies.

Contribution

It introduces a joint analysis of energy harvesting and transfer, deriving performance bounds and optimization methods for systems with finite batteries.

Findings

Wireless energy transfer significantly enhances system performance.

Online optimization approaches can achieve near-optimal results.

Energy transfer benefits persist even with energy wastage.

Abstract

One of the main concerns in traditional Wireless Sensor Networks (WSNs) is energy efficiency. In this work, we analyze two techniques that can extend network lifetime. The first is Ambient \emph{Energy Harvesting} (EH), i.e., the capability of the devices to gather energy from the environment, whereas the second is Wireless \emph{Energy Transfer} (ET), that can be used to exchange energy among devices. We study the combination of these techniques, showing that they can be used jointly to improve the system performance. We consider a transmitter-receiver pair, showing how the ET improvement depends upon the statistics of the energy arrivals and the energy consumption of the devices. With the aim of maximizing a reward function, e.g., the average transmission rate, we find performance upper bounds with and without ET, define both online and offline optimization problems, and present results based on realistic energy arrivals in indoor and outdoor environments. We show that ET can significantly improve the system performance even when a sizable fraction of the transmitted energy is wasted and that, in some scenarios, the online approach can obtain close to optimal performance.