Analysis of GNSS Multipath Effects and Performance Degradation in Vegetated Environments
Accurate positioning of Global Navigation Satellite System (GNSS) is essential for civil applications but degrades in harsh environments, especially in vegetated environments. While building impacts on GNSS performance are well-studied, vegetation effects remain poorly characterized. Although existing studies have analyzed observation-level behaviors like positioning errors, their underlying causes remain unclear. This study investigates GNSS performance in vegetated environments through observation- and signal-level analyses. Vegetation-induced attenuation alters GNSS signal strength patterns, rendering conventional positioning strategies ineffective. Signal-level analysis using intermediate-frequency (IF) data and maximum likelihood multipath estimators reveals distinctive external multipath characteristics and internal scattering effects under vegetation. Tracking error analysis further shows error distributions under vegetation that differ from those in nonvegetation environments. Based on these findings, the extension of the existing positioning method to perform adaptive positioning is explored, demonstrating the potential benefits of incorporating vegetation effects to improve GNSS positioning accuracy.