Satellite Clock and Ephemeris Error Bounding Characterization for Galileo and Estimated CNAV

Abstract

The Advanced Receiver Autonomous Integrity Monitoring (ARAIM) concept relies on characterizing the satellite clock and ephemeris bounding parameters. In this paper, we expand on the previous study on the GPS error bounding parameters to include Galileo and the approximation of the bounding parameters of the Civil Navigation (CNAV) Message type. In particular, we compute the bounding parameters that capture their inherent variability. We then partition the error by their observable conditions to determine whether the currently collected data is representative of future error behavior. Furthermore, for Galileo, we change the nominal error definition to investigate how it would affect the bounding parameter distribution. We find that the Galileo normalized error data are bounded with Gaussian with mean of 0.04 and standard deviation of 0.04 for different partitions with newer satellites having more stable and lower bounding parameters. Lowering the nominal error definition threshold stabilizes the bounding parameters. We estimate the CNAV bounding parameter by lowering the σURA values. We find the normalized errors are bounded with Gaussian with mean of 0.41 and standard deviation of 1.15 even after lowering the σ URA values. In addition, lowering the σ URA values stabilizes the bounding parameters.