The Age of Updates in a Simple Relay Network

TL;DR

This paper analyzes the age of information in a relay network with server vacations, deriving a closed-form average age expression and optimizing packet generation rates to minimize age, with potential applications to complex multi-hop systems.

Contribution

It introduces a novel analytical approach to compute and optimize the average age in a relay network with server vacations, extending queuing theory tools.

Findings

Derived a closed-form expression for average age in the system.

Optimized packet generation rates to minimize average age.

Numerical results validate theoretical analysis and show stream interactions.

Abstract

In this paper, we examine a system where status updates are generated by a source and are forwarded in a First-Come-First-Served (FCFS) manner to the monitor. We consider the case where the server has other tasks to fulfill, a simple example being relaying the packets of another stream. Due to the server's necessity to go on vacations, the age process of the stream of interest becomes complicated to evaluate. By leveraging specific queuing theory tools, we provide a closed form of the average age for both streams which enables us to optimize the generation rate of packets belonging to each stream to achieve the minimum possible average age. The tools used can be further adopted to provide insights on more general multi-hop scenarios. Numerical results are provided to corroborate the theoretical findings and highlight the interaction between the two streams.