Age of Information Upon Decisions

TL;DR

This paper introduces the concept of Age upon Decisions (AuD) to measure update freshness at decision times in an M/M/1 system, revealing that decision rate does not affect AuD, but increasing arrival and service rates can improve timeliness.

Contribution

It derives a closed-form expression for average AuD in an M/M/1 system and analyzes how system parameters influence update freshness at decision epochs.

Findings

Average AuD depends on arrival and service rates, not decision rate.

Increasing decision rate alone does not improve update freshness.

Higher arrival and service rates reduce average AuD effectively.

Abstract

We consider an M/M/1 update-and-decide system where Poisson distributed decisions are made based on the received updates. We propose to characterize the freshness of the received updates at decision epochs with Age upon Decisions (AuD). Under the first-come-first-served policy (FCFS), the closed form average AuD is derived. We show that the average AuD of the system is determined by the arrival rate and the service rate, and is independent of the decision rate. Thus, merely increasing the decision rate does not improve the timeliness of decisions. Nevertheless, increasing the arrival rate and the service rate simultaneously can decrease the average AuD efficiently.