A new study has introduced a novel approach for reducing multipath effects in satellite navigation through the use of overlap-frequency signals from Global Positioning System (GPS), Galileo, and Beidou-3 Navigation Satellite System (BDS-3). Employing an interoperable Multipath Hemispherical Map (MHM), this technique significantly boosts positioning precision across these systems by as much as 25%. This advancement marks a pivotal step towards efficiently disentangling global navigation satellite systems (GNSS) from the constraints of multipath effects, thereby bolstering positioning precision and catalyzing progress in high-precision applications, notably within the realm of geodesy.
Multipath effects, resulting from satellite signals reflecting off objects before reaching the receiver, seriously compromise the precision of satellite navigation systems. Existing solutions like Sidereal Filtering and system-specific MHMs require the observations spanning at least one full cycle of satellite orbit repeat period (e.g., ten days for Galileo) to reproduce the satellite geometry against ground stations. As a consequence, the practicability of SF and MHM is limited due to potential station-surrounding changes over a long period. With the ongoing challenges these effects present, it is imperative to develop more advanced and flexible solutions to improve multipath modeling efficiency and GNSS positioning precision.
The study (DOI: 10.1186/s43020-024-00144-7), led by Jianghui Geng from the GNSS Research Center at Wuhan University and co-authored by experts from both the Chinese Academy of Sciences and the University of Tokyo, was published in Satellite Navigation on 15 July 2024. Utilizing data from 21 European stations, this research not only enhances our understanding of the GPS, Galileo, and BDS-3 systems but also highlights the efficacy of using overlap-frequency signals in applications demanding high precision. Furthermore, they have introduced this multipath modeling module within the open source software PRIDE PPP-AR v3.1 (https://github.com/PrideLab/PRIDE-PPPAR), offering an efficient tool to mitigate multipath effects, beneficial for GNSS high-precision positioning applications.
The investigation entailed a detailed analysis over 31 days of data from 21 European stations, assessing the newly devised MHM_GEC model against established GNSS-specific MHMs and Sidereal Filtering techniques. The findings revealed that MHM_GEC, which amalgamates data from the GPS, Galileo, and BDS-3 systems, markedly excels in mitigating multipath effects. The MHM_GEC, constructed using 5 to 6 days of data, can enhance positioning precision by 40%, outperforming the traditional GNSS-specific MHMs and sidereal filtering established with 10 days of data. This performance boost is credited to the model's ability to effectively use overlap-frequency signals from different constellations, markedly enhancing spatial resolution, modeling efficiency, and multipath correction performance.
Dr. Yosuke Aoki, co-author and geospatial engineering expert, remarked, "The interoperable MHM model marks a significant milestone in satellite navigation technologies. It notably enhances the accuracy of positioning systems, which is essential for everything from geodesy to autonomous vehicles."
The potential impacts of this research are broad, set to transform industries that depend on precise positioning, such as maritime navigation, deformation monitoring and geodesy. By minimizing the margin of error, the interoperable MHM model not only boosts system reliability but also opens up new possibilities for applications that require exceedingly precise location data.
