Added Benefit of the BDS III B2a Signal for Precise GNSS Positioning with Automotive Grade Receivers

Stefan Junker, Nataliya Mishukova, Victor Gomez, Aeson Copeland, Michael Reupold, Christian Schmidt, Ramzi El Khayat, Divya Santhanam, Tobias Koeglsberger, Michele Iafrancesco

Abstract:	The emerging automotive applications raised the necessity for a reliable highly accurate absolute GNSS positioning which is a crucial requirement for autonomous vehicles. With the purpose of meeting the mass market demands, these applications require the use of automotive-grade GNSS chipsets that usually follow a trade-off between availability of the measurements, measurement quality, power consumption, and production cost. The automotive-grade chipsets track selected frequency bands for each constellation reaching at most two frequencies per satellite system and varying from one chipset to another. While the first generation of such chipsets had focused on providing the signals on the second frequency for GPS and Galileo constellations, the next generation additionally provides the B2a signal of the BeiDou III system, China’s third-generation global satellite navigation system. The presentation will demonstrate that the additional BeiDou signal can further enhance several aspects of precise GNSS positioning. With the limited availability of GPS satellites with L2 (available on 23 satellites) and L5 (16 satellites) signals as well as the 24 Galileo satellites providing E5a or E5b signals, the BeiDou III system will add another 24 dual-frequency MEO satellites to the automotive receiver processing. In other words, the BeiDou B2a signal increases the availability of dual-frequency measurements by 37% in a GPS L1/L5 system. The positioning performance analysis incorporates several techniques that allow us to demonstrate the added benefit of the B2a signal by processing the data from automotive-grade chipsets that provide dual-frequency measurements using Trimble’s high precision PVT engine in combination with Trimble’s regional augmented correction data (CenterPoint® RTX Fast). In a classic initial analysis approach we will show the convergence times of positioning errors with the dual-frequency GPS, Galileo and BeiDou measurements collected in a static open-sky scenario. Next we will take the chipsets on the road and compare positioning performance with and without additional B2a signal in the typical assisted/autonomous driving scenarios like highway and suburban areas. Moreover, we will assess the position re-convergence performance after the signal outages caused by highway overpasses and road signs, where the added benefit of the B2a signal will become apparent as it will assist with accelerating the ambiguity resolution after the cycle slips on most of the signals, that is required to reach desired low-decimeter positioning accuracy. In addition to the accuracy, the re-convergence time is another key metric to define the performance of a GNSS-only positioning system in automotive applications, as this is the time additional sensors need to propagate the precise absolute position. Finally, we will perform an analysis of test drives executed in Europe and Asia to show an additional impact of the signals provided by dual-frequency IGSO and GEO satellites. The purpose of this presentation is to demonstrate added benefits of the BeiDou III B2a signal on the GNSS positioning performance with mass-market chipsets in the typical automotive environments using Trimble’s next-generation PVT engine as well as Trimble RTX service. Both the impact on the accuracy as well as re-convergence times is assessed. The analysis performed is the first and most comprehensive assessment of the BeiDou III benefits in the area of automotive mass-market PPP applications.
Published in:	Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021) September 20 - 24, 2021 Union Station Hotel St. Louis, Missouri
Pages:	697 - 724
Cite this article:	Junker, Stefan, Mishukova, Nataliya, Gomez, Victor, Copeland, Aeson, Reupold, Michael, Schmidt, Christian, Khayat, Ramzi El, Santhanam, Divya, Koeglsberger, Tobias, Iafrancesco, Michele, "Added Benefit of the BDS III B2a Signal for Precise GNSS Positioning with Automotive Grade Receivers," Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021), St. Louis, Missouri, September 2021, pp. 697-724. https://doi.org/10.33012/2021.17913
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