Minimizing Age of Information with Generate at Will Status Updates and Age-Agnostic Cyclic Scheduling

TL;DR

This paper introduces age-agnostic cyclic scheduling algorithms for multi-source generate-at-will systems to minimize weighted age of information, providing analytical methods and optimal patterns especially for two sources.

Contribution

It develops an analytical approach for exact average AoI, derives a closed-form optimal pattern for two sources, and proposes the IS algorithm for general sources, outperforming existing schemes.

Findings

Optimal transmission patterns for two sources derived in closed form.

IS algorithm effectively constructs near-optimal patterns for multiple sources.

Age-agnostic cyclic schedulers achieve low AoI with low complexity.

Abstract

We study the scheduling problem for a multi-source single-server generate-at-will (GAW) status update system with sources having heterogeneous service times and weights, with the goal of minimizing the weighted sum age of information (AoI). In particular, we study \emph{age-agnostic} schedulers which rely only on the first two moments of the source service times and they are relatively easier to implement than their age-aware counterparts which make use of the actual realizations of the service times. In particular, we focus on age-agnostic cyclic schedulers with $O(1)$ runtime complexity where status updates from multiple sources are scheduled according to a fixed finite transmission pattern. We first develop an analytical method to obtain the exact average AoI of each source when a transmission pattern is given. Then, we derive the optimum transmission pattern in closed form for the specific case of two sources. For general number of sources, we propose a novel algorithm, called IS (Insertion Search), for constructing transmission patterns, and we show that IS is capable of producing the optimum pattern for two-source systems, and it outperforms other existing age-agnostic schemes, for the case of more than two sources. Numerical examples are presented to showcase the effectiveness of the proposed approach.