DFMC SBAS Resiliency: Dual-Frequency Service Advantages During 2024 Ionospheric Storms

Juan Manso, Ignacio José Díaz, Javier Arenas, and Ramón Sánchez-Verdejo

Abstract:	Satellite-Based Augmentation Systems (SBAS) are regional wide-area augmentation systems that enhance the accuracy, availability, continuity, and integrity of Global Navigation Satellite Systems (GNSS), providing critical support for civil aviation. Current single-frequency SBAS implementations, such as the Wide Area Augmentation System (WAAS) and European Geostationary Navigation Overlay Service (EGNOS), broadcast corrections for the GPS L1 C/A signal following the RTCA DO229 standard. This standard includes a thin-shell ionospheric model that corrects the delay of the signal in the ionosphere through the Grid Ionospheric Vertical Delay (GIVD) and its associated variance (GIVE). During severe ionospheric storms driven by solar activity—characterized by large TEC fluctuation, scintillation, radio bursts, and plasma bubbles—this model cannot adequately capture the extreme variability, leading to inflated GIVE, reduced availability, and potential integrity threats that limit SBAS performance for safety-of-life applications. Dual-Frequency Multi-Constellation (DFMC) SBAS provides a robust solution by exploiting dual-frequency signals (GPS L1/L5 and Galileo E1/E5a) to directly eliminate the ionospheric delay. This removes the dependence on ionospheric models, significantly improving positioning accuracy and resilience during disturbed ionospheric conditions. This paper analyzes GNSS data from solar cycle 25, which has exhibited intense activity. The cycle’s two worst geomagnetic storms up to 2024 have been selected—10–11 May 2024 and 10–11 October 2024—supplemented with additional data from the same year. Using GMV’s magicSBAS demonstrator and GMV’s magicGEMINI user algorithms, realistic SBAS messages and user solutions were generated and assessed under storm conditions. Results show that DFMC SBAS consistently maintained low error levels and preserved availability margins, whereas single-frequency SBAS experienced performance degradation. These findings highlight the importance of adopting DFMC SBAS for safety-critical domains, such as aviation and air traffic management, where service continuity and reliability are paramount.
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:	457 - 489
Cite this article:	Manso, Juan, Díaz, Ignacio José, Arenas, Javier, Sánchez-Verdejo, Ramón, "DFMC SBAS Resiliency: Dual-Frequency Service Advantages During 2024 Ionospheric Storms," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 457-489. https://doi.org/10.33012/2025.20359
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