# Average Age of Information in Wireless Powered Sensor Networks

## TL;DR

This paper analyzes the average age of information in wireless powered sensor networks, deriving closed-form expressions and optimizing capacitor size to enhance data freshness in energy-harvesting sensor systems.

## Contribution

It provides the first analytical model for AoI in WPT sensor networks and identifies the optimal capacitor size for maximizing information freshness.

## Key findings

- Closed-form expression for average AoI derived.
- Optimal capacitor size for best AoI identified.
- Performance bounds for practical WPT networks established.

## Abstract

In this letter, we deal with the age of information (AoI) for a sensor network with wireless power transfer (WPT) capabilities. Specifically, we study a simple network topology, where a sensor node harvests energy from radio frequency signals (transmitted by a dedicated energy source) to transmit real-time status updates. The sensor node generates an update when its capacitor/battery becomes fully charged and transmits by using all the available energy without further energy management. The average AoI performance of the considered greedy policy is derived in closed form and is a function of the capacitor's size. The optimal value of the capacitor that maximizes the freshness of the information, corresponds to a simple optimization problem requiring a one-dimensional search. The derived theoretical results provide useful performance bounds for practical WPT networks.