GNSS Code Multipath Mitigation by Cascading Measurement Monitoring Techniques

Area of Science:

• Geomatics Engineering
• Satellite Navigation Systems
• Signal Processing

Background:

• Multipath interference from Global Navigation Satellite Systems (GNSS) signals degrades positioning accuracy.
• Existing mitigation techniques include error correction, stochastic weighting, and measurement exclusion/de-weighting.

Purpose of the Study:

• To investigate and propose advanced techniques for mitigating GNSS code multipath errors.
• To enhance the robustness and accuracy of positioning solutions in challenging environments.

Main Methods:

• A comprehensive review of multipath mitigation strategies.
• Focus on detection/exclusion and de-weighting techniques using single and dual-frequency metrics.
• Introduction of a new Geometry-Free (GF) detection metric combined with Code-Minus-Carrier (CMC) error correction.
• Investigation of geometry-based algorithms for handling multiple simultaneously affected measurements.

Main Results:

• The proposed combined method demonstrated over 38% improvement for GPS L1 compared to conventional Carrier-to-Noise-density ratio (C/N₀)-based Least-Squares (LS) solutions.
• Effectiveness shown in static and kinematic scenarios, except in deep urban canyons.
• Reduced performance observed for L2C and L5 frequencies due to limited satellite visibility.

Conclusions:

• The novel GF metric and combined approach offer significant improvements in GNSS positioning accuracy by effectively mitigating multipath effects.
• The method is particularly effective for GPS L1 signals, preserving measurement geometry and reducing data loss.
• Further research may be needed to optimize performance for other GNSS frequencies and challenging environments.