Analysis of Age of Information in Non-terrestrial Networks

TL;DR

This paper analyzes the timeliness of information delivery in non-terrestrial networks, especially LEO satellite systems, using Age of Information metrics and stochastic geometry to derive a closed-form expression for average AoI.

Contribution

It introduces an on-off process model for NTN service and derives a novel closed-form expression for average AoI, enhancing understanding of LEO satellite network performance.

Findings

The derived expression accurately predicts AoI in NTN scenarios.

Source update rate significantly affects the average AoI.

Satellite constellation density impacts information freshness.

Abstract

Non-terrestrial networks (NTN), particularly low Earth orbit (LEO) satellite networks, have emerged as a promising solution to overcome the limitations of traditional terrestrial networks in the context of next-generation (6G) wireless systems. In this paper, we focus on analyzing the timeliness of information delivery in NTN through the concept of Age of Information (AoI). We propose an on-off process to approximate the service process between LEO satellites and a source node located on the Earth's surface. By utilizing stochastic geometry, we derive a closed-form expression for the time-average AoI in an NTN. This expression also applies to on-off processes with one component following an exponential distribution while the other has its probability density function supported on a bounded interval. Numerical results validate the accuracy of our analysis and demonstrate the impact of source status update rate and satellite constellation density on the time-average AoI. Our work fills a gap in the literature by providing a comprehensive analysis of AoI in NTN and offers new insights into the performance of LEO satellite networks.