Estimating the Probability of Galileo I/Nav Navigation With Osnma: “If You Can Navigate, Can You Authenticate?”

This work presents the probability of a Galileo receiver calculating a position fix and an OSNMA (Open Service Navigation Message Authentication) position fix in different environments, including discontinuous signal reception. To complement real-data tests already available, the results are based on simulations using AWGN (Additive White Gaussian Noise) and simplified LMS (Land Mobile Satellite) channels, combined with assumptions on satellite visibility to model opensky, urban and hard urban environments. TTFF (Time To First Fix) and TTFAF (Time To First Authenticated Fix) are compared for each environment for a 10 -minute window, corresponding to the usual navigation refresh rate. While the results focus on corner cases where the TTFF is achieved within the window, but not TTFAF, identifying the reasons, in most cases TTFF and TTFAF are both achieved.