ARAIM Integrity Support Message parameter validation by online ground monitoring

In this paper we introduce a ground monitoring architecture to validate the Integrity Support Message (ISM) parameters to be used by aircraft for Advanced Receiver Autonomous Integrity Monitoring (ARAIM). This work focuses on two critical ISM parameters: P sat, which designates the prior probabilities of satellite faults, and b max, which is a range domain bound on small faults that may occur at probabilities higher than P sat. We show that the choices of b max and P sat are not independent. The paper first establishes the relationship between b max, Psat , Time to Integrity Alert (TIA) and constellation service provider performance commitments. We then provide an example ground monitor design that detects inter-frequency bias faults and code-carrier divergence faults. We show that the performance of the monitor can be used to validate specific b max and P sat values for ARAIM.