The BeiDou global broadcast ionospheric delay correction model (BDGIM) and its preliminary performance evaluation results

A global ionospheric delay correction model (BeiDou global broadcast ionospheric delay correction model [BDGIM]) is proposed for the single-frequency ionospheric delay correction of the third phase of the BeiDou navigation satellite system (BDS-3). An initial performance assessment of BDGIM was conducted with data collected in China and worldwide. For regional analysis, the broadcast coefficients of BDGIM were provided by the operational control system of BDS, while for global analysis, the coefficients of BDGIM were estimated using global positioning system (GPS)-derived total electron contents (TECs) obtained from 19 globally distributed monitoring sites. In China, the performance of BDGIM was evaluated by GPS-TEC derived from 40 test sites during day of year (DOY) 060 to 181, 2015. The ionospheric errors can be mitigated by 80.9% for BDGIM. On the global scale, the ionospheric TECs derived from 50 sites of the International Global Navigation Satellite System (GNSS) Services (IGS) were used as references during DOY 220 to 365, 2014, and BDGIM can correct for 77.6% of the ionospheric delay.