An improved algorithm of ionospheric grid correction based on gps and compass multi-constellation

Ionosphere delay is one of the main sources of error for single frequency user location and is the main factor influencing the integrity monitoring, which is the major problem in the building of the Beidou SBAS. At present, the Wide Area Augmentation System (WAAS) uses the Kriging method to estimate the Grid Ionospheric Vertical Delay (GIVD) and Grid Ionospheric Vertical Delay Error (GIVE). On the basis of the traditional Kriging method, some domestic scholars have proposed an improved Kriging method, taking into account the temporal correlation of IPP delay values, using the IPP delay values in the update cycle for algorithm to obtain more reasonable GIVE Value. However, because the GPS satellite constellation are all the MEO satellites, IPP observation position change over time, it is not easy to obtain accurate time variogram model. Specially, there are five GEO satellites in China’s Beidou system, the IPP position formed by the reference station observing GEO satellites is almost fixed, so we introduce the Beidou GEO satellite observations in this paper, the accurate time variogram model was obtained and the improved Kriging algorithm for the Chinese region is given. In this paper, the ionospheric data of Beijing regional monitoring station are used to study. First, the spatial correlation characteristics of ionospheric delay in northern China were researched. Then, the 5 GEO satellites in Compass are selected to study the ionospheric temporal variation. Finally, we conduct a simulation on ionospheric delay estimation at IGPs in Multi-constellation through Kriging and Improved Kriging algorithm. It can be concluded that, in the premise of satisfying integrity, the GIVE is reduced more than 30% in most parts of north China; therefore, the User Ionospheric Vertical Delay Error (UIVE) can more closely envelop the correction error.