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LEO-based Carrier-Phase Positioning for 6G: Design Insights and Comparison with GNSS

Harish K. Dureppagari, Harikumar Krishnamurthy, Chiranjib Saha, Xiaofeng Wang, Alberto Rico-Alvariño, R. Michael Buehrer, Harpreet S. Dhillon

Abstract

The integration of non-terrestrial networks (NTN) into 5G new radio (NR) enables a new class of positioning capabilities based on cellular signals transmitted by Low-Earth Orbit (LEO) satellites. In this paper, we investigate joint delay-and-carrier-phase positioning for LEO-based NR-NTN systems and provide a convergence-centric comparison with Global Navigation Satellite Systems (GNSS). We show that the rapid orbital motion of LEO satellites induces strong temporal and geometric diversity across observation epochs, thereby improving the conditioning of multi-epoch carrier-phase models and enabling significantly faster integer-ambiguity convergence. To enable robust carrier-phase tracking under intermittent positioning reference signal (PRS) transmissions, we propose a dual-waveform design that combines wideband PRS for delay estimation with a continuous narrowband carrier for phase tracking. Using a realistic simulation framework incorporating LEO orbit dynamics, we demonstrate that LEO-based joint delay-and-carrier-phase positioning achieves cm-level accuracy with convergence times on the order of a few seconds, whereas GNSS remains limited to meter-level accuracy over comparable short observation windows. These results establish LEO-based cellular positioning as a strong complement and potential alternative to GNSS for high-accuracy positioning, navigation, and timing (PNT) services in future wireless networks.

LEO-based Carrier-Phase Positioning for 6G: Design Insights and Comparison with GNSS

Abstract

The integration of non-terrestrial networks (NTN) into 5G new radio (NR) enables a new class of positioning capabilities based on cellular signals transmitted by Low-Earth Orbit (LEO) satellites. In this paper, we investigate joint delay-and-carrier-phase positioning for LEO-based NR-NTN systems and provide a convergence-centric comparison with Global Navigation Satellite Systems (GNSS). We show that the rapid orbital motion of LEO satellites induces strong temporal and geometric diversity across observation epochs, thereby improving the conditioning of multi-epoch carrier-phase models and enabling significantly faster integer-ambiguity convergence. To enable robust carrier-phase tracking under intermittent positioning reference signal (PRS) transmissions, we propose a dual-waveform design that combines wideband PRS for delay estimation with a continuous narrowband carrier for phase tracking. Using a realistic simulation framework incorporating LEO orbit dynamics, we demonstrate that LEO-based joint delay-and-carrier-phase positioning achieves cm-level accuracy with convergence times on the order of a few seconds, whereas GNSS remains limited to meter-level accuracy over comparable short observation windows. These results establish LEO-based cellular positioning as a strong complement and potential alternative to GNSS for high-accuracy positioning, navigation, and timing (PNT) services in future wireless networks.
Paper Structure (7 sections, 6 figures)

This paper contains 7 sections, 6 figures.

Table of Contents

  1. Introduction
  2. Carrier-Phase Measurements & Tracking
  3. Convergence Analysis and Positioning Performance
  4. Conditioning of Phase Evolution Transformation Matrix
  5. Integer Ambiguity Resolution
  6. Positioning Performance: Joint Delay-and-Carrier-Phase
  7. Research Landscape and Open Problems

Figures (6)

  • Figure 1: Introduction to Carrier Phase: Carrier phase measurements over time.
  • Figure 2: Dual waveform.
  • Figure 3: Carrier Phase evolution and error: GNSS vs. LEO: a) True phase and Doppler approximation over time (G - GNSS, L - LEO, TP - True Phase, and DA - Doppler Approximation); b) error (difference between TP and DA) due to Doppler approximation over time.
  • Figure 4: Condition Number Analysis: GNSS vs. LEO: Conditioning of phase evolution transformation matrix over measurement time.
  • Figure 5: Integer Ambiguity Resolution: GNSS vs. LEO: Integer ambiguity resolution over measurement time.
  • ...and 1 more figures