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Projecte llegit

Títol: Simulation Framework for Hybrid MEO/LEO Satellite Navigation and PNT Performance Analysis

Estudiants que han llegit aquest projecte:

Director/a: PARK, HYUK

Departament: FIS

Títol: Simulation Framework for Hybrid MEO/LEO Satellite Navigation and PNT Performance Analysis

Data inici oferta: 04-02-2026     Data finalització oferta: 04-10-2026


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Satellite, GNSS, LEO PNT, Communications, Simulation
 
Descripció del contingut i pla d'activitats:
Objectives
The goal of this work is to design and implement a flexible and computationally efficient
simulation framework for the analysis of satellite-based navigation performance. With focus
on evaluating satellite visibility, geometric configuration, and positioning quality for different
GNSS constellations and potential LEO-PNT augmentation concepts.
Using MATLAB as the development environment, the framework combines satellite orbit
propagation, user location modeling, and geometry-based performance evaluation.
The tool aims to allow systematic analysis and comparison of different constellations and
operational scenarios, such as elevation mask selection, user location, and regional
constraints. In addition, studying the effect of introducing a limited LEO-PNT layer as a
complementary navigation source to assess potential improvements in geometry and
robustness. A modular structure is proposed to analyze different configurations and regions
of interest, while supporting time-dependent simulations over several hours or days.
Ultimately, the framework is intended to support navigation-oriented performance analysis
and provide insight into geometry-driven limitations of satellite positioning systems.
Methodology
The simulator will be implemented in MATLAB to model satellite orbits, coordinate
transformations, and user-satellite geometry. GNSS satellite positions will be computed from
publicly available orbital data, while custom constellations, including simplified LEO-PNT
configurations, will be generated from orbital parameters such as altitude, inclination, RAAN,
and phasing. User locations will be defined either as fixed points or regions for geographic
relevance.
Satellite visibility will be determined using line-of-sight conditions and elevation angle
thresholds. Navigation performance will be evaluated using geometry-based metrics,
including the number of visible satellites and dilution of precision parameters (GDOP, PDOP,
HDOP, VDOP, TDOP). Time-dependent simulations will be carried out to capture the
evolution of satellite geometry. The functions will enable testing of different constellations,
elevation masks, and hybrid GNSS + LEO scenarios.
Expected Results
The simulator is expected to provide quantitative metrics and visualizations describing
satellite visibility and geometry-based navigation performance for different constellations and
regions. Time histories, statistical indicators, and regional maps of DOP metrics will be
produced for multiple scenarios. The results will allow comparison between GNSS-only and
hybrid GNSS + LEO-PNT configurations, highlighting geometry-driven benefits and
limitations.
Future extensions may include integrity-related studies or the incorporation of additional PNT
concepts.
 
Overview (resum en anglès):
Global Navigation Satellite Systems operating from Medium Earth Orbit provide foundational positioning, navigation, and timing services worldwide. However, their signals suffer from significant path loss and low received power, making them highly vulnerable to signal attenuation, multipath, and geometric degradation in dense urban environments and high latitude regions. Emerging Low Earth Orbit positioning architectures offer higher signal power and rapid geometric dynamics, yet testing these hybrid concepts remains constrained by the high cost of physical deployment and the lack of flexible open-source evaluation packages.

This Final Degree Project presents the design and implementation of a modular, computationally efficient MATLAB simulation framework to analyze satellite navigation performance across traditional MEO constellations and modern LEO augmentation concepts. Built as an extensible architecture, the simulator incorporates orbit propagation, atmospheric propagation models including Saastamoinen tropospheric delay and Klobuchar ionospheric corrections, three-state multipath modeling, and site-specific geographic obstructions via OpenStreetMap vector data or Copernicus land-cover rasters.

The performance engine evaluates single-frequency code pseudorange observations using Weighted Least Squares estimation to compute Dilution of Precision metrics, parameter covariance matrices, directional uncertainties, horizontal and vertical protection levels, and Doppler-based dynamic velocity error estimations. Through three dedicated operational modes, regional coverage mapping, static user assessment, and dynamic route performance, the simulator evaluates positioning quality across multi-scale scenarios. Experimental results demonstrate that hybrid MEO and LEO architectures can compress horizontal uncertainty footprints and significantly reduce severe dilution of precision spikes in deep urban canyons. The developed simulation framework provides a cost-effective and transparent tool for evaluating these architectures, supporting mission planning and autonomous navigation applications.

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