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

2026-03-18

AI Summary

This work proposes a novel integrated time-delay and carrier-phase positioning method leveraging low Earth orbit (LEO) satellites within a 5G non-terrestrial network to overcome the limitations of traditional GNSS, which struggles to achieve centimeter-level accuracy under short observation windows due to slow integer ambiguity convergence. The approach introduces an innovative dual-waveform architecture: a wideband signal enables high-precision time-delay estimation, while a narrowband continuous carrier supports robust phase tracking. Exploiting the high velocity of LEO satellites enhances spatiotemporal and geometric diversity, significantly improving the condition number of the multi-epoch carrier-phase model and accelerating ambiguity resolution. Experimental results demonstrate centimeter-level positioning accuracy within seconds—substantially outperforming GNSS’s meter-level performance—and validate the potential of LEO-based cellular positioning as a viable complement or even alternative for high-precision PNT services in 6G.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation
• Search and Optimization: Learning to Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Location- and context-aware Web and WoT applications and services
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

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.

Problem

• LEO-based positioning
• carrier-phase positioning
• GNSS comparison
• high-accuracy PNT
• integer ambiguity convergence

Innovation

• LEO-based positioning
• carrier-phase ambiguity resolution
• dual-waveform design
• temporal-geometric diversity
• cm-level accuracy