Assessment of Ionospheric Corrections Algorithms Using the GNSS Laboratory Tool Suite (gLAB): From STEC to Navigation Performance

Users of the Global Navigation Satellite System (GNSS) using a single-frequency receiver need to use an Ionospheric Correction Algorithm (ICA) to compensate the delay introduced by the Ionosphere on radio waves. The European GNSS, Galileo, uses an ICA named NeQuick-G since it is an adaptation to real time use of the 3D climatological model NeQuick, whereas the American Global Positioning Service (GPS) uses the Klobuchar ICA, which was also adopted initially by the Chinese GNSS, Beidou. In an effort to foster the adoption of NeQuick-G by final users, two implementations in C language were made publicly available by the European Space Agency (ESA) and the Joint Research Centre (JRC) of the European Commission (EC) respectively. The latter, was chosen to be integrated in the GNSS laboratory tool suite (gLAB), developed by the research group of Astronomy and Geomatics (gAGE) of the Universitat Politecnica de Catalunya (UPC) because its open license and its processing speed. The aim of the present contribution is to compare the Slant Total Electron Content (STEC) predictions of the two aforementioned ICAs and assess their differences in the navigation domain using the gLAB tool. For this purpose, we have used multi-frequency data for several hundreds of stations distributed worldwide belonging to the International GNSS Service (IGS) network. For each first day of the month during year 2019, the outcomes STECs of the two ICAs have been compared in terms of accuracy, availability and execution time. For completeness and inter-comparisons, STEC from post-processed Global Ionospheric Maps from IGS have been also been accounted for. Then, for each station involved in the experiment, positioning errors have been analyzed while using the different ionospheric corrections.