Freshness on Demand: Optimizing Age of Information for the Query Process

TL;DR

This paper introduces a new metric called Age of Information at Query (QAoI) for pull-based communication systems, optimizing information freshness specifically at query times, which differs from traditional push-based AoI approaches.

Contribution

It models the discrete, query-dependent nature of information freshness, proposing QAoI as a more relevant metric for pull-based systems and demonstrating its different optimization strategies.

Findings

QAoI differs significantly from traditional AoI in pull-based systems.

Optimizing QAoI leads to different transmission policies compared to push-based AoI.

The model applies to Packet Erasure Channels, showing practical relevance.

Abstract

Age of Information (AoI) has become an important concept in communications, as it allows system designers to measure the freshness of the information available to remote monitoring or control processes. However, its definition tacitly assumed that new information is used at any time, which is not always the case and the instants at which information is collected and used are dependent on a certain query process. We propose a model that accounts for the discrete time nature of many monitoring processes, considering a pull-based communication model in which the freshness of information is only important when the receiver generates a query. We then define the Age of Information at Query (QAoI), a more general metric that fits the pull-based scenario, and show how its optimization can lead to very different choices from traditional push-based AoI optimization when using a Packet Erasure Channel (PEC).