Simulation study of mitigation of plasma bubble effects on GBAS using a VHF radar

Abstract

Plasma bubbles can affect ground-based augmentation system (GBAS) performance by posing large spatial ionospheric gradients between the aircraft and the airport, which makes it important to detect plasma bubbles effectively. In this study, we investigate the use of VHF radar to detect plasma bubbles and mitigate their potential impact on GBAS through a simulation. When the line-of-sight of a certain GPS satellite is determined to be passing through an area of plasma bubbles as detected by EAR, such GPS satellite shall be removed from the positioning calculation on board the aircraft. We set up different simulation scenarios by varying the satellite geometry, and airport coordinate. Results are described in the form of vertical protection level (VPL) and vertical position error (VPE), which we then analyse as a function of zonal and meridional distance. The results show that such a radar-based monitoring system can be used to mitigate the effects of plasma bubbles on GBAS to cover surrounding airports within a certain range, especially in the meridional direction.