Age of information cost minimization with no buffers, random arrivals and unreliable channels: A PCL-indexability analysis

TL;DR

This paper extends Whittle's index policy to a broader Age of Information scheduling model with no buffers, random arrivals, and unreliable channels, providing closed-form index expressions and insights on scheduling priorities.

Contribution

It establishes indexability for a complex AoI model with no buffers and unreliable channels, deriving closed-form Whittle indices and analyzing parameter impacts.

Findings

Established indexability using partial conservation laws.

Derived closed-form Whittle index expressions.

Provided insights into scheduling priorities based on model parameters.

Abstract

Over the last decade, the Age of Information has emerged as a key concept and metric for applications where the freshness of sensor-provided data is critical. Limited transmission capacity has motivated research on the design of tractable policies for scheduling information updates to minimize Age of Information cost based on Markov decision models, in particular on the restless multi-armed bandit problem (RMABP). This allows the use of Whittle's popular index policy, which is often nearly optimal, provided indexability (index existence) is proven, which has been recently accomplished in some models. We aim to extend the application scope of Whittle's index policy in a broader AoI scheduling model. We address a model with no buffers incorporating random packet arrivals, unreliable channels, and nondecreasing AoI costs. We use sufficient indexability conditions based on partial conservation laws previously introduced by the author to establish the model's indexability and evaluate its Whittle index in closed form under discounted and average cost criteria. We further use the index formulae to draw insights on how scheduling priority depends on model parameters.