Worldwide SBAS Broadcasts Between 2017 and 2022: A Comparative Study

Abstract

The Satellite-Based Augmentation Systems (SBAS) provide safe civil aviation navigation services for En-route through LPV-200 precision approach operations. Current operational L1 SBASs improve user accuracy and integrity over specific regions by monitoring the GPS satellites in conjunction with ionosphere effects on GNSS signal propagation. At this moment, the development and establishment of the SBAS systems are at a turning point. This transition is motivated by several elements, like the extension of the traditional L1 SBAS services to new regionals areas, the introduction of the DFMC SBAS services, or the consideration of multidomain uses beyond the aviation services. SBAS L1 systems have been already commissioned and operated in the United States (WAAS), the European Union (EGNOS), India (GAGAN) and Japan (MSAS). Additionally, SBAS deployments are currently underway in other regions, including Australia and New Zealand (SouthPAN), China (BDSBAS), Korea (KASS), Russia (SDCM), Algeria (ASAL) and Africa (NSAS/ASECNA). In addition, during 2022 the United Kingdom SBAS Testbed (UKSBAS) started broadcasting its messages. Between 2017 and 2022, more than twenty SBAS L1 GEO PRN signals have been broadcast belonging to eight different SBAS systems. The main aim of this paper is to analyze the status of all these SBAS systems including WAAS, EGNOS, GAGAN, MSAS, SouthPAN, BDSBAS, SDCM, ASAL and NSAL during the last five years. The SBAS augmentation messages are obtained from available open FTPs (mainly supported by CNES, IGS and EGNOS) and processed with GMV’s Satellite Ranging Error Analyzer (SREA) platform to obtain a statistical characterization of their satellite and ionosphere information error. The paper provides several metrics, including satellite orbit and clock error, user range error histograms and time-series, or operational systems UDRE bound ratios. The tool is also able to review the ionospheric performances, with indicators such as the GIVD corrections availability, accuracy, and the operational systems GIVE bound ratio over the long-time historical data available. In conclusion, this paper will give a detailed analysis of the accuracy and integrity of some of the SBAS systems worldwide and the evolution of their performances during the last few years.