Improving the ionospheric delay correction of satellite-based augmentation systems in equatorial regions

In 2005, China designed and constructed independent satellite systems ‘Beidou II’, which indicated the start of a new area in Chinese space-based positioning, navigation and timing systems. It is necessary and important to investigate the performance of ionospheric delay correction in the region of China. In this paper, a new algorithm of satellite-based augmentation systems (SBAS) ionospheric delay correction is proposed and tested using observational data at 18 GPS stations. The data are used during periods from January 4 to 23, 2000. The computing results show that precision is high for user stations in the higher mid-latitudes with the average root mean square (RMS) of around 0.4 m. The precision is relatively lower for the lower latitude, which is more prominent for the equatorial region from latitude 20°N to 25°N and from longitude 100°E to 120°E. Quite a few prediction errors surpass 2 m, and the worst case reaches a maximum of 3 m.