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

TL;DR

This paper explores LEO satellite-based cellular positioning, demonstrating cm-level accuracy and rapid convergence, offering a promising alternative to GNSS for high-precision PNT services in 6G networks.

Contribution

It introduces a joint delay-and-carrier-phase positioning method for LEO-based 5G systems and compares its performance with GNSS, highlighting advantages in convergence speed and accuracy.

Findings

LEO satellite motion enhances multi-epoch positioning conditioning.

Proposed dual-waveform design improves carrier-phase tracking robustness.

LEO-based positioning achieves cm-level accuracy within seconds.

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.