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Leveraging Aerial Platforms for Downlink Communications in Sparse Satellite Networks

Chang-Sik Choi

TL;DR

This work addresses reliable downlink communications in sparse satellite networks by introducing aerial platforms as relays. It proposes a space-time 4D stochastic framework based on a Cox point process to jointly model moving satellites on orbital tracks and the positions of aerial platforms relative to ground gateways. The paper derives closed-form expressions for key metrics including effective satellites, connectivity probability, SNR coverage, end-to-end throughput, and association delay, illustrating substantial performance gains from aerial platforms. These results indicate that aerial platforms can achieve coverage, reliability, and latency comparable to dense satellite deployments, offering a practical alternative when deploying many satellites is infeasible.

Abstract

Although a significant number satellites are deemed essential for facilitating diverse applications of satellite networks, aerial platforms are emerging as excellent alternatives for enabling reliable communications with fewer satellites. In scenarios with sparse satellite networks, aerial platforms participate in downlink communications, serving effectively as relays and providing comparable or even superior coverage compared to a large number of satellites. This paper explores the role of aerial platforms in assisting downlink communications, emphasizing their potential as an alternative to dense satellite networks. Firstly, we account for the space-time interconnected movement of satellites in orbits by establishing a stochastic geometry framework based on an isotropic satellite Cox point process. Using this model, we evaluate space-and-time performance metrics such as the number of orbits, the number of communicable satellites, and the connectivity probability, primarily assessing the geometric impact of aerial platforms. Subsequently, we analyze signal-to-noise ratio (SNR) coverage probability, end-to-end throughput, and association delay. Through examination of these performance metrics, we explicitly demonstrate how aerial platforms enhance downlink communications by improving various key network performance metrics that would have been achieved only by many satellites, thereby assessing their potential as an excellent alternative to dense satellite networks.

Leveraging Aerial Platforms for Downlink Communications in Sparse Satellite Networks

TL;DR

This work addresses reliable downlink communications in sparse satellite networks by introducing aerial platforms as relays. It proposes a space-time 4D stochastic framework based on a Cox point process to jointly model moving satellites on orbital tracks and the positions of aerial platforms relative to ground gateways. The paper derives closed-form expressions for key metrics including effective satellites, connectivity probability, SNR coverage, end-to-end throughput, and association delay, illustrating substantial performance gains from aerial platforms. These results indicate that aerial platforms can achieve coverage, reliability, and latency comparable to dense satellite deployments, offering a practical alternative when deploying many satellites is infeasible.

Abstract

Although a significant number satellites are deemed essential for facilitating diverse applications of satellite networks, aerial platforms are emerging as excellent alternatives for enabling reliable communications with fewer satellites. In scenarios with sparse satellite networks, aerial platforms participate in downlink communications, serving effectively as relays and providing comparable or even superior coverage compared to a large number of satellites. This paper explores the role of aerial platforms in assisting downlink communications, emphasizing their potential as an alternative to dense satellite networks. Firstly, we account for the space-time interconnected movement of satellites in orbits by establishing a stochastic geometry framework based on an isotropic satellite Cox point process. Using this model, we evaluate space-and-time performance metrics such as the number of orbits, the number of communicable satellites, and the connectivity probability, primarily assessing the geometric impact of aerial platforms. Subsequently, we analyze signal-to-noise ratio (SNR) coverage probability, end-to-end throughput, and association delay. Through examination of these performance metrics, we explicitly demonstrate how aerial platforms enhance downlink communications by improving various key network performance metrics that would have been achieved only by many satellites, thereby assessing their potential as an excellent alternative to dense satellite networks.

Paper Structure

This paper contains 38 sections, 8 theorems, 55 equations, 14 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Related Work
  3. Theoretical Contributions
  4. Space-time Model for Satellite Dynamics and Downlink Communications
  5. Space and Time Performance Analysis
  6. Key Design Insights to Real-World Problems
  7. System Model
  8. Satellites and Aerial Platforms Modeling
  9. Aerial Platform-Assisted Downlink Communications
  10. Propagation Model
  11. Performance Metrics
  12. Preliminary
  13. Time invariant
  14. Spherical cap
  15. Arc length
  16. ...and 23 more sections

Key Result

Theorem 1

In the typical extended spherical cap, the average number of effective orbits is $\lambda\sin(\mkern 1.5mu\overline{\mkern-1.5mu\varphi\mkern-1.5mu}\mkern 1.5mu)$ and the average number of effective satellites is given by respectively, where $\mkern 1.5mu\overline{\mkern-1.5mu\varphi\mkern-1.5mu}\mkern 1.5mu = \arccos(r_e/r_a) + \arccos(r_e/r_s)$ and $r_e<r_a<r_s.$

Figures (14)

  • Figure 1: Aerial platform-assisted satellite downlink communications.
  • Figure 2: This figure visualizes the network connectivity improved by an aerial platform. The extended spherical cap (solid blue) represents the area visible from the aerial platform at $A$ whereas the visible spherical cap (dashed orange) represents the area visible from the typical terrestrial gateway at $U.$
  • Figure 3: For the orbit (solid line), the longitude is $\theta,$ the inclination is $\phi$. Its satellite has an argument angle of $\omega$. The argument angle is the angle of the satellite from the point $A$, measured over the corresponding orbit.
  • Figure 4: The proposed network with $\lambda=20$ and $\mu=50$.
  • Figure 5: The circle marks indicate the average number of effective satellites without aerial platforms whereas the diamond marks indicate the average number of effective satellites with aerial platforms at the altitude of $20$ km.
  • ...and 9 more figures

Theorems & Definitions (13)

  • Theorem 1
  • Example 1
  • Theorem 2
  • Example 2
  • Theorem 3
  • Theorem 4
  • Example 3
  • Theorem 5
  • Theorem 6
  • Remark 1
  • ...and 3 more