Closed-Loop Dynamic Multi-Path Parameter Estimation for Urban Canyon Navigation

Zhihang Qu, Yong Li, Wenhui Yang, Daifang Huang

Peer Reviewed

Abstract:	In dense urban environments, Global Navigation Satellite System (GNSS) signal propagation is frequently distorted by dynamic short-delay multi-path effects, which arise from reflections off buildings, vehicles, and other structures. These effects significantly degrade pseudo-range measurements and remain one of the primary challenges for achieving high-accuracy positioning in urban navigation. Traditional multi-path estimation methods suffer from limited resolution, poor adaptability to time-varying conditions, and high computational cost, making them unsuitable for real-time applications. To address these limitations, this paper presents a novel dynamic multi-path parameter estimation framework that integrates time-frequency analysis with vector tracking. Specifically, the Short-Time Fractional Fourier Transform (STFrFT) is applied to represent GNSS correlation signals in both time and frequency domains. This enables accurate characterization of time-varying multi-path features, including delay spread and Doppler frequency shifts. Multi-path parameters—such as delay, Doppler shift, and Doppler rate—are estimated using multi-order FrFT transformations. The signal path with the smallest Doppler rate is selected as the line-of-sight (LOS) component for vector tracking, while FrFT parameter selection is refined using vector tracking predictions to reduce the search space and improve computational efficiency. A prediction-correction loop is introduced to iteratively optimize the estimation process. Simulation experiments, conducted under realistic urban environment assumptions, demonstrate that the proposed method can achieve delay estimation accuracy of 0.2 chips and sub-Hz Doppler precision. The results confirm the effectiveness of combining time-frequency analysis with vector tracking for robust, high-resolution multi-path mitigation in dynamic urban environments, offering a promising solution for enhanced GNSS positioning in intelligent transportation and autonomous vehicle applications.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	1926 - 1938
Cite this article:	Qu, Zhihang, Li, Yong, Yang, Wenhui, Huang, Daifang, "Closed-Loop Dynamic Multi-Path Parameter Estimation for Urban Canyon Navigation," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 1926-1938. https://doi.org/10.33012/2025.20425
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