LEO-based Positioning: Foundations, Signal Design, and Receiver Enhancements for 6G NTN

2024-10-23

arXiv.org

AI Summary

To address positioning, navigation, and timing (PNT) requirements for 6G non-terrestrial networks (NTNs), this work overcomes performance bottlenecks of conventional terrestrial cellular positioning—namely, large propagation delays, high Doppler shifts, and limited multi-satellite coordination—by proposing a GNSS-independent, high-accuracy LEO satellite PNT paradigm. Methodologically, it introduces wide-area positioning beams orthogonal to communication beams; designs a UE-side time-domain joint search and parameter estimation algorithm tailored to LEO high-velocity dynamics; and enables efficient multi-satellite reuse of positioning reference signals (PRS) within the NR resource grid. An end-to-end simulation framework is built by integrating NR-NTN physical-layer modeling, orbital dynamics simulation, and joint Doppler-delay compensation, augmented by compressed sensing for accelerated PRS detection. Experimental validation demonstrates horizontal positioning accuracy better than 10 m in representative urban and open-sky scenarios, confirming its technical feasibility as both a GNSS complement and potential alternative.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation
• Application Domains: Mobility, Driving & Flight

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Location- and context-aware Web and WoT applications and services
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Security and Privacy: Large-scale security measurements

Abstract

The integration of non-terrestrial networks (NTN) into 5G new radio (NR) has opened up the possibility of developing a new positioning infrastructure using NR signals from Low-Earth Orbit (LEO) satellites. Compared to existing Global Navigation Satellite Systems (GNSS), LEO-based cellular positioning offers several advantages, such as a superior link budget, higher operating bandwidth, and large forthcoming constellations. Due to these factors, LEO-based positioning, navigation, and timing (PNT) is a potential enhancement for NTN in 6G cellular networks. However, extending the existing terrestrial cellular positioning methods to LEO-based NTN positioning requires key fundamental enhancements. These include creating broad positioning beams orthogonal to conventional communication beams, time-domain processing at the user equipment (UE) to resolve large delay and Doppler uncertainties, and efficiently accommodating positioning reference signals (PRS) from multiple satellites within the communication resource grid. In this paper, we present the first set of design insights by incorporating these enhancements and thoroughly evaluating LEO-based positioning, considering the constraints and capabilities of the NR-NTN physical layer. To evaluate the performance of LEO-based NTN positioning, we develop a comprehensive NR-compliant simulation framework, including LEO orbit simulation, transmission (Tx) and receiver (Rx) architectures, and a positioning engine incorporating the necessary enhancements. Our findings suggest that LEO-based NTN positioning could serve as a complementary infrastructure to GNSS and, with appropriate enhancements, may also offer a viable alternative.

Problem

• Enhancing LEO-based positioning for 6G NTN networks
• Designing orthogonal positioning beams and signal processing
• Evaluating LEO positioning as a GNSS complement or alternative

Innovation

• Orthogonal positioning beams for LEO-NTN
• Time-domain UE processing for delay resolution
• Efficient PRS integration in communication grid