# Age of Information in a Network of Preemptive Servers

## TL;DR

This paper analyzes the age of information in a network with preemptive servers, providing a characterization of how information freshness evolves through the network for Poisson update arrivals.

## Contribution

It offers a novel analysis of age of information in networks with preemptive memoryless servers, including explicit formulas for average age at each node.

## Key findings

- Average age increases through successive network nodes.
- Explicit formulas for age at input and output of each node.
- Age accumulation is characterized for Poisson arrivals in line networks.

## Abstract

A source submits status updates to a network for delivery to a destination monitor. Updates follow a route through a series of network nodes. Each node is a last-come-first-served queue supporting preemption in service. We characterize the average age of information at the input and output of each node in the route induced by the updates passing through. For Poisson arrivals to a line network of preemptive memoryless servers, we show that average age accumulates through successive network nodes.