Ionospheric modeling and accuracy evaluation of multi-system GNSS in high-latitude region

Ionospheric delay is one of the main error sources that affect the positioning and navigation accuracy. The accurate establishment of ionospheric model is significant for high-precision navigation and positioning. Aiming at the research of multi-GNSS ionospheric modeling in high-latitude region, the multi-GNSS ionospheric modeling method is first given, and then the ionospheric modeling is carried out by using the observation datasets of 11 MGEX stations distributed uniformly in high-latitude region. The modeling accuracy of GPS system and multi-GNSS systems is compared and analyzed under the ionospheric polynomial model and spherical harmonic model. The results show that the difference between the differential code bias (DCB) estimates of each system calculated by the two ionospheric models is small, and the deviation of most of the satellite DCB estimates is less than 0.5 ns. For both two ionospheric models, the coefficient estimation accuracy under multi-GNSS systems is better than that under single GPS system, as well as the VTEC residual is smaller than that under single GPS system. The modeling accuracy of the ionospheric harmonic model is 3.09 TECU for single system and 1.80 TECU for multi-GNSS systems, with an improvement of 41.7%.