Doppler shifts from LEO satellites enable precise positioning without GNSS
Beyond GNSS: Leveraging LEO Satellite Signals of Opportunity for Doppler Positioning
Information Theory
Summary
Traditional GPS systems sometimes fail when their signals are blocked or unavailable. The authors show that signals from low Earth orbit (LEO) satellites, which move fast and cause changes in signal frequency called Doppler shifts, can help find locations even when GPS is not an option. Their research uses existing satellite signals and publicly available satellite orbit data to calculate positions. They also developed a simulation tool to realistically test this approach and found it works well in both city and open areas.
What this means in practice
- •For telecommunications engineers: Enhance user device location accuracy in urban and remote areas where GNSS signals are weak or blocked by using LEO satellite Doppler shifts.
- •For emergency response coordinators: Enable precise positioning for first responders in GNSS-denied environments using existing LEO satellite signals and available orbital data.
Authors
Md. Ali Hasan, M. Humayun Kabir, Sangmin Han, Wonjae Shin, H. Vincent Poor
Abstract
Large constellations of low Earth orbit (LEO) satellites provide ubiquitous global connectivity; yet, their rapid motion introduces significant Doppler shift effects. While challenging for communication, these effects can be leveraged for precise user terminal (UT) positioning, particularly in GNSS-denied environments where traditional satellite-based navigation struggles. Unlike GNSS, most LEO satellites lack dedicated navigation signals, motivating signals-of-opportunity (SOPs) approaches that repurpose existing LEO signals and use publicly available two-line element (TLE) files for orbital information, although ephemeris errors can limit accuracy. This article explores the fundamental principles, challenges, and enabling technologies for LEO-based Doppler shift positioning, highlighting its advantages over conventional non-Doppler methods, and discussing future research directions. Furthermore, to facilitate realistic and reproducible performance evaluation beyond stochastic modeling, we propose SionnaNTN-RT, a ray tracing framework for non-terrestrial network (NTN) built upon Sionna, enabling end-to-end simulation of Doppler-based positioning. Simulation results demonstrate that Doppler-based positioning can achieve high positioning accuracy in both urban and open-sky environments, highlighting its promise for next-generation positioning systems.