Algorithm Optimization and Terminal Validation of BDSBAS Ionospheric Correction

The BeiDou Satellite Based Augmentation System (BDSBAS) achieved Initial Operating Capability (IOC) from 2020, which is embedded into BDS as a component. The ionospheric enhancement corrections provided by BDSBAS protects users from threats generated by ionospheric disturbances. This paper addresses the ionospheric algorithm applied in BDSBAS, which consist of the Grid Ionospheric Vertical Delay (GIVD), its corresponding error bound called Grid Ionospheric Vertical Error (GIVE) and the processors used in BDSBAS ionospheric solution. The performance of BDSBAS ionospheric enhancement service is analysed, focusing on service coverage, ionospheric delay correction accuracy and corresponding integrity risk. Results shows that the BDSBAS ionospheric enhancement service basically cover all airspaces over China and surrounding area, with a satellite cut-off angle of 15 degrees at the boundary. Compared to the rapid Global Ionospheric Map (GIM), the accuracy of BDSBAS GIVD is about 2.0–3.0 TEC unit (TECU) during Day of Year (DOY) 130–160, 2021. No misleading information appeared during the test period which indicates that the probability of hazardously misleading information of BDSBAS ionospheric correction is limited below 10–7 per approach.