BDGIM performance evaluation based on iGMAS global tracking network

Abstract

The third phase BeiDou Navigation Satellite System (BDS-3) provides a BeiDou Global broadcast Ionospheric delay correction Model (BDGIM) for single-frequency navigation and positioning applications. According to the BDS Interface Control Document (ICD) Signal B1C (Version 1.0), the BDGIM contains nine parameters and was broadcast in December 2018. The BDGIM will gradually replace the BDS-2 ionospheric 8-parameter Klobuchar model (BDSKlob). A preliminary evaluation of the BDGIM was conducted using data collected at multiple stations across the international GNSS Monitoring and Assessment System (iGMAS) global tracking network. The high-precision global grid ionospheric delay sequences obtained from the Center of Orbit Determination in Europe (CODE) were selected as references to evaluate the BDGIM performance worldwide. The synthetic analysis and comparison results show that the BDGIM provides the best global description of the ionosphere and improves the nocturnal performance of the Klobuchar model and its sharp increase in the Polar Regions. The VTEC (Vertical Total Electron Content) calculated by the BDGIM exhibited the smallest RMS (Root Mean Square) values, the highest precision, and better performance for most northern hemisphere latitudes. BDGIM RMS values for most world regions were generally less than 5 TECU (Total Electron Content Unit), and its ionospheric delay correction rate reached nearly 80%.