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

TL;DR

This paper explores the potential of LEO satellite signals for 6G positioning, introducing key enhancements to existing methods and evaluating their performance through a comprehensive simulation framework.

Contribution

It presents the first detailed design insights and evaluation framework for LEO-based NTN positioning, addressing fundamental challenges and proposing solutions for integration into 6G networks.

Findings

LEO-based positioning can complement GNSS infrastructure.

Proposed enhancements improve delay and Doppler resolution.

Simulation results show viability of LEO-based NTN positioning.

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.