Scheduling Algorithms for Minimizing Age of Information in Wireless Broadcast Networks with Random Arrivals: The No-Buffer Case

TL;DR

This paper develops and analyzes scheduling algorithms for minimizing the age of information in wireless broadcast networks with random arrivals, using MDP and index-based methods for both offline and online scenarios.

Contribution

It introduces structural MDP and index scheduling algorithms that reduce complexity and provide asymptotic optimality for age minimization in wireless broadcast networks.

Findings

Algorithms asymptotically minimize average age.

Index-based algorithms perform well with equal arrival rates.

Structural results simplify computation and derivation of indices.

Abstract

Age of information is a new network performance metric that captures the freshness of information at end-users. This paper studies the age of information from a scheduling perspective. To that end, we consider a wireless broadcast network where a base-station (BS) is updating many users on random information arrivals under a transmission capacity constraint. For the offline case when the arrival statistics are known to the BS, we develop a structural MDP scheduling algorithm and an index scheduling algorithm, leveraging Markov decision process (MDP) techniques and the Whittle's methodology for restless bandits. By exploring optimal structural results, we not only reduce the computational complexity of the MDP-based algorithm, but also simplify deriving a closed form of the Whittle index. Moreover, for the online case, we develop an MDP-based online scheduling algorithm and an index-based online scheduling algorithm. Both the structural MDP scheduling algorithm and the MDP-based online scheduling algorithm asymptotically minimize the average age, while the index scheduling algorithm minimizes the average age when the information arrival rates for all users are the same. Finally, the algorithms are validated via extensive numerical studies.