Availability Assessment of Dual-Frequency GNSS-Based Augmentation Systems Under Equatorial Ionospheric Scintillations

This study investigates a wide range of equatorial scintillations to evaluate their impacts on the availability of dual-frequency Global Navigation Satellite System (GNSS)-based augmentation systems. A two-component power-law phase screen model is used to implement scintillation simulations for all possible sets of phase screen parameters within their empirical range. Two types of scintillation effects, phase transition and loss of lock, are conservatively quantified in terms of navigation availability. This study specifies equatorial scintillation conditions with the scintillation indicators, S4 and ?0, to search for the worst scintillation impact among all simulation results assigned to each grid of S4 and ?0. Aviation availability of a GPS/Galileo dual-frequency advanced receiver autonomous integrity monitoring (ARAIM) is assessed for the scintillation scenario selected from the real scintillation data. The simulation results show that the availability is highly dependent on the reacquisition time and the C/N0 threshold which are closely related to the receiver design specifications and user settings. The proposed approach allows availability assessment of GNSSbased augmentation systems for any scintillation conditions specified by indicators {S4, ?0} where the indicators can be obtained in near real-time.