Performance Analysis of Average Peak Age of Information in LEO Satellite-Enabled IoT Networks

The significant volume of data exchanged in large-scale Internet of Things (IoT) networks presents a major challenge for terrestrial service providers, often leading to difficulties in maintaining required data transmission delays. Additionally, IoT devices are frequently deployed in remote areas lacking terrestrial coverage. This ensures the need to shift these transmissions to non-terrestrial networks, such as Low Earth Orbit (LEO) satellites (referred to as LEOSATs in the rest of the paper), which provide low transmission delays due to their reliable connections. IoT networks increasingly support real-time applications, which makes the freshness of transmitted data essential. The Age of Information (AoI) metric is introduced to address this need. This work considers a large-scale IoT network served by LEOSATs, where the locations of the ground IoT nodes and LEOSATs follow two independent Poisson Point Processes (PPPs) with different intensities. To guarantee update transmission reliability, this work focuses on the Peak AoI (PAoI) of the transmitted update between the ground IoT source node and its ground data controller relying on the LEOSATs. Using tools from stochastic geometry, we derive expressions for the uplink and downlink coverage probabilities at the nodes of interest. These expressions are then used to determine the overall average PAoI in the system. Furthermore, we examine the impact of various parameters on the overall average PAoI in the system, considering two different LEOSAT constellations: a Low-density LEOSAT constellation and a high-density LEOSAT constellation. Numerical results demonstrate the impact of varying the altitudes of LEOSATs and the total number of LEOSATs in the system, for the two LEOSAT densities. Additionally, the numerical results show how variations in arrival rates impact the overall average PAoI.