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Joint Mechanical and Electrical Adjustment of IRS-aided LEO Satellite MIMO Communications

Doyoung Kim, Seongah Jeong

TL;DR

This paper addresses enhancing downlink LEO satellite MIMO performance by jointly optimizing a mechanically tilted intelligent reflecting surface (IRS) and the associated transceiver beamformers. It develops a 3D MIMO channel model for general IRS deployment and analyzes two scenarios: with and without a direct LEO–GU link. The authors derive closed-form or SVD-based solutions for tilt, IRS phase shifts, and transmit/receive beamformers, demonstrating substantial end-to-end SNR gains through numerical results calibrated with Orbcomm orbit data. The findings show that joint mechanical and electrical IRS design yields pronounced improvements, particularly when 3D angular alignment is leveraged, and pave the way for future multi-satellite/multi-user extensions.

Abstract

In this correspondence, we propose a joint mechanical and electrical adjustment of intelligent reflecting surface (IRS) for the performance improvements of low-earth orbit (LEO) satellite multiple-input multiple-output (MIMO) communications. In particular, we construct a three-dimensional (3D) MIMO channel model for the mechanically-tilted IRS in general deployment, and consider two types of scenarios with and without the direct path of LEO-ground user link due to the orbital flight. With the aim of maximizing the end-to-end performance, we jointly optimize tilting angle and phase shift of IRS along with the transceiver beamforming, whose performance superiority is verified via simulations with the Orbcomm LEO satellite using a real orbit data.

Joint Mechanical and Electrical Adjustment of IRS-aided LEO Satellite MIMO Communications

TL;DR

This paper addresses enhancing downlink LEO satellite MIMO performance by jointly optimizing a mechanically tilted intelligent reflecting surface (IRS) and the associated transceiver beamformers. It develops a 3D MIMO channel model for general IRS deployment and analyzes two scenarios: with and without a direct LEO–GU link. The authors derive closed-form or SVD-based solutions for tilt, IRS phase shifts, and transmit/receive beamformers, demonstrating substantial end-to-end SNR gains through numerical results calibrated with Orbcomm orbit data. The findings show that joint mechanical and electrical IRS design yields pronounced improvements, particularly when 3D angular alignment is leveraged, and pave the way for future multi-satellite/multi-user extensions.

Abstract

In this correspondence, we propose a joint mechanical and electrical adjustment of intelligent reflecting surface (IRS) for the performance improvements of low-earth orbit (LEO) satellite multiple-input multiple-output (MIMO) communications. In particular, we construct a three-dimensional (3D) MIMO channel model for the mechanically-tilted IRS in general deployment, and consider two types of scenarios with and without the direct path of LEO-ground user link due to the orbital flight. With the aim of maximizing the end-to-end performance, we jointly optimize tilting angle and phase shift of IRS along with the transceiver beamforming, whose performance superiority is verified via simulations with the Orbcomm LEO satellite using a real orbit data.
Paper Structure (7 sections, 1 theorem, 25 equations, 5 figures, 1 table)

This paper contains 7 sections, 1 theorem, 25 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. System Model
  3. Optimization of IRS-aided LEO satellite communication systems
  4. Optimal design for Scenario I without direct link
  5. Optimal solution for Scenario II
  6. Numerical Results
  7. Conclusions

Key Result

Lemma 1

When the angular deviation between the LEO satellite-GU link and the LEO satellite-IRS link on the satellite side is minimal, leading to $\pmb{a}_{t,D}^{S \mathrel{ \mkern-5mu\hbox{)}}\space G}(\pmb{\psi}_{t,D}^{S \mathrel{ \mkern-5mu\hbox{)}}\space G}) \approx \pmb{a}_{t,D}^{S \mathrel{

Figures (5)

  • Figure 1: System model of IRS-aided LEO satellite communications.
  • Figure 2: Illustration of angular relationship with tilting angle of $\eta_t$. (a) 2D illustration of tilted IRS (b) 3D illustration of tilted IRS
  • Figure 3: Received SNR versus the coverage time $t$ with Scenario I and II.
  • Figure 4: Received SNR versus the vertical distance from $y$-$z$ plane of the IRS to the GU $l_V$.
  • Figure 5: Received SNR versus the number of reflecting elements $M$ with high elevation angle.

Theorems & Definitions (1)

  • Lemma 1