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LEO Satellite and RIS: Two Keys to Seamless Indoor and Outdoor Localization

Pinjun Zheng, Xing Liu, Yuchen Zhang, Jiguang He, Gonzalo Seco-Granados, Tareq Y. Al-Naffouri

TL;DR

The paper addresses the need for universal indoor-outdoor localization by combining low Earth orbit (LEO) satellites with reconfigurable intelligent surfaces (RIS). It presents a feasibility study with both theoretical and simulation-based analyses, showing that RIS-enabled LEO localization can achieve meter-level accuracy in challenging indoor environments, outperforming traditional MEO and GNSS approaches. The work outlines two RIS paradigms—active RIS and STAR-RIS—and examines their impact on localization performance, while also proposing system architectures (transparent vs regenerative) and identifying key challenges in signal processing, handover management, and STAR-RIS hardware fabrication. The results suggest that global, seamless localization is achievable through coordinated LEO-RIS infrastructure, with significant implications for next-generation localization-aware networks and 5G/6G ecosystems.

Abstract

The contemporary landscape of wireless technology underscores the critical role of precise localization services. Traditional global navigation satellite systems (GNSS)-based solutions, however, fall short when it comes to indoor environments, and existing indoor localization techniques such as electromagnetic fingerprinting methods face challenges of additional implementation costs and limited coverage. This article explores an innovative solution that blends low Earth orbit (LEO) satellites with reconfigurable intelligent surfaces (RISs), unlocking its potential for realizing seamless indoor and outdoor localization (SIOL) with global coverage. After a comprehensive review of the distinctive characteristics of LEO satellites and RISs, we showcase their potential for SIOL applications through two case studies on position error bound evaluation. Finally, we discuss system architectures and highlight open challenges in such systems.

LEO Satellite and RIS: Two Keys to Seamless Indoor and Outdoor Localization

TL;DR

The paper addresses the need for universal indoor-outdoor localization by combining low Earth orbit (LEO) satellites with reconfigurable intelligent surfaces (RIS). It presents a feasibility study with both theoretical and simulation-based analyses, showing that RIS-enabled LEO localization can achieve meter-level accuracy in challenging indoor environments, outperforming traditional MEO and GNSS approaches. The work outlines two RIS paradigms—active RIS and STAR-RIS—and examines their impact on localization performance, while also proposing system architectures (transparent vs regenerative) and identifying key challenges in signal processing, handover management, and STAR-RIS hardware fabrication. The results suggest that global, seamless localization is achievable through coordinated LEO-RIS infrastructure, with significant implications for next-generation localization-aware networks and 5G/6G ecosystems.

Abstract

The contemporary landscape of wireless technology underscores the critical role of precise localization services. Traditional global navigation satellite systems (GNSS)-based solutions, however, fall short when it comes to indoor environments, and existing indoor localization techniques such as electromagnetic fingerprinting methods face challenges of additional implementation costs and limited coverage. This article explores an innovative solution that blends low Earth orbit (LEO) satellites with reconfigurable intelligent surfaces (RISs), unlocking its potential for realizing seamless indoor and outdoor localization (SIOL) with global coverage. After a comprehensive review of the distinctive characteristics of LEO satellites and RISs, we showcase their potential for SIOL applications through two case studies on position error bound evaluation. Finally, we discuss system architectures and highlight open challenges in such systems.
Paper Structure (23 sections, 7 figures, 2 tables)

This paper contains 23 sections, 7 figures, 2 tables.

Table of Contents

  1. Introduction
  2. LEO Satellite
  3. LEO Satellite-Based Localization
  4. Why Is the LEO Satellite a Key Enabler for SIOL?
  5. Reconfigurable Intelligent Surface
  6. RIS-Aided Localization
  7. Theoretical Algorithm Design
  8. Realistic Studies
  9. How Can RIS Enhance SIOL?
  10. Active RIS
  11. STAR-RIS
  12. Simulation Studies
  13. Simulation Setup
  14. PEB vs. Number of Satellites
  15. PEB vs. User's Positions
  16. ...and 8 more sections

Figures (7)

  • Figure 1: Conceptual diagram of seamless indoor and outdoor localization services enabled by LEO satellites and RISs. With the involvement of STAR-RISs, LEO satellite signals can extend into indoor areas thus enabling and enhancing indoor localization, while outdoor users can benefit from both reflecting-only RISs and STAR-RISs.
  • Figure 2: Comparative features of satellites in GEO, MEO, and LEO.
  • Figure 3: A summary of satellite transmitter configurations, space-to-ground propagation losses, and outdoor-to-indoor penetration losses for GEO, MEO, and LEO satellites.
  • Figure 4: Active RIS with reflection-type amplifiers and STAR-RIS with independent control of refraction (i.e., transmission) and reflection.
  • Figure 5: Theoretical PEB vs. the number of LEO/MEO satellites, comparing scenarios with and without active STAR-RIS.
  • ...and 2 more figures