Stochastic Geometry and Dynamical System Analysis of Walker Satellite Constellations
In practice, low Earth orbit (LEO) and medium Earth orbit (MEO) satellite networks consist of multiple orbits which are populated with many satellites. A widely used spatial architecture for LEO or MEO satellites is the Walker constellation, where the longitudes of orbits are equally spaced and the satellites are equally spaced along the orbits. In this paper, we develop a stochastic geometry model for the Walker constellations. This proposed model enables an analysis based on dynamical system theory, which allows one to address essential structural properties such as periodicity and ergodicity. It also enables a stochastic geometry analysis under which we derive the performance of downlink communications of a typical user at a given latitude, as a function of the key constellation parameters.
Analysis of a Delay-Tolerant Data Harvest Architecture Leveraging Low Earth Orbit Satellite Networks
Reaching all regions of Earth, low Earth orbit (LEO) satellites can harvest delay-tolerant data from remotely located users on Earth without ground infrastructure. This work aims to assess a data harvest network architecture where users generate data and LEO satellites harvest data from users when passing by. By developing a novel stochastic geometry Cox point process model that simultaneously generates orbits and the motion of LEO satellite harvesters on them, we analyze key performance indices of such a network by deriving the following: (i) the average fraction of time that the typical user is served by LEO satellite harvesters, (ii) the average amount of data uploaded per each satellite pass, (iii) the maximum harvesting capacity of the proposed network model, and (iv) the delay distribution in the proposed network. These key metrics are given as functions of key network variables such as λ the mean number of orbits and μ the mean number of satellites per orbit. Providing rich comprehensive analytical results and practical interpretations of these results, this work assesses the potential of the delay-tolerant use of LEO satellites and also serves as a versatile framework to analyze, design, and optimize delay-tolerant LEO satellite networks.
Modeling and Analysis of Downlink Communications in a Heterogeneous LEO Satellite Network
Low Earth Orbit (LEO) satellite networks are rapidly expanding to support a wide range of services—such as data communications, remote sensing, and data harvesting—and will increasingly share spectrum among multiple operators. To investigate the coexistence of such future heterogeneous LEO networks, we propose a tractable spatial model based on Cox point processes, capturing satellite distributions across various orbits. We analyze downlink performance under two access schemes: closed access and open access. Our results show that open access consistently yields better coverage probability for all users. By offering key network performance metrics and demonstrating the suitability of the Cox model in approximating future constellations with minor variability, our framework provides a practical foundation for designing, evaluating, and optimizing heterogeneous LEO satellite networks.
An Analytical Framework for Downlink LEO Satellite Communications
This work develops an analytical framework for downlink low earth orbit (LEO) satellite communications, leveraging tools from stochastic geometry. We propose a tractable approach to the analysis of such satellite communication systems accounting for the fact that satellites are located on circular orbits. We accurately characterize this geometric property of such LEO satellite constellations by developing a Cox point process model that jointly produces orbits and satellites on these orbits. Our work differs from existing studies that have assumed satellites' locations as completely random binomial point processes.
Spatially-correlated Blockage in Highway Vehicular Networks
The line-of-sight (LOS) signals play a significant role in enabling various applications. For instance, in positioning systems, users or vehicles can estimate their relative distances and positions based on the time-of-arrivals (ToAs) and time- of-departures (ToDs) of LOS signals from anchors. This work presents a stochastic geometric framework modeling and analyzing spatially correlated blockage in a highway vehicular network.
Analysis of Vehicle-to-everything (V2X) Communications
This work analyzes an emerging architecture of cellular network utilizing both planar base stations uniformly distributed in the Euclidean plane and base stations (or RSUs) located on roads. An example of this architecture is that where, in addition to conventional planar cellular base stations and users, vehicles also play the role of both base stations and users. A Cox point process is used to model the location of base stations.
Data harvesting through vehicle gateways
Disruptive changes are underway in the automotive industry as large-scale platforms based on vehicular fleets are deployed to deliver ride sharing and delivery services. This stuey examines a network architecture based on a mesh of IoT devices, roadside repositories and vehicular mobile gateways -- referred to as mesh+vehicular. We propose a system-level model to study its relative merits versus conventional infrastructure-based IoT architectures-- referred to as mesh+cellular.
Performance Analysis of Vehicle Safety Message
This paper concerns the performance of vehicle-to-everything (V2X) communications. More precisely, we analyze the broadcast of safety-related V2X communications in cellular networks where base stations and vehicles are assumed to share the same spectrum and vehicles broadcast their safety messages to neighboring users.
Priority-based Access Control in Vehicular Networks
This paper analyzes priority-based distributed ac- cess control in vehicular networks. Characterizing the spatial correlation between vehicles, users, and roads, this paper uses a Cox point process to model vehicles and users, respectively. Then, this paper proposes that each vehicle transmits if it has the highest priority among all of its neighbors.