Timeliness of Status Update System: The Effect of Parallel Transmission Using Heterogeneous Updating Devices

TL;DR

This paper analyzes the Age of Information in multi-queue IoT status update systems with heterogeneous devices, deriving closed-form expressions and demonstrating performance improvements over traditional systems.

Contribution

It introduces a stochastic hybrid systems model for analyzing AoI in parallel updating systems with heterogeneous devices, providing new insights and closed-form solutions.

Findings

Logarithm of average AoI decreases linearly with log of total arrival rate or number of devices.

Proposed systems outperform FCFS M/M/N status update system.

Numerical results confirm the accuracy of the analytical model.

Abstract

Timely status updating is the premise of emerging interaction-based applications in the Internet of Things (IoT). Using redundant devices to update the status of interest is a promising method to improve the timeliness of information. However, parallel status updating leads to out-of-order arrivals at the monitor, significantly challenging timeliness analysis. This work studies the Age of Information (AoI) of a multi-queue status update system where multiple devices monitor the same physical process. Specifically, two systems are considered: the Basic System, which only has type-1 devices that are ad hoc devices located close to the source, and the Hybrid System, which contains additional type-2 devices that are infrastructure-based devices located in fixed points compared to the Basic System. Using the Stochastic Hybrid Systems (SHS) framework, a mathematical model that combines discrete and continuous dynamics, we derive the expressions of the average AoI of the considered two systems in closed form. Numerical results verify the accuracy of the analysis. It is shown that when the number and parameters of the type-1 devices/type-2 devices are fixed, the logarithm of average AoI will linearly decrease with the logarithm of the total arrival rate of type-2 devices or that of the number of type-1 devices under specific condition. It has also been demonstrated that the proposed systems can significantly outperform the FCFS M/M/N status update system.