Multi-constellation RAIM for simultaneous double-fault satellite scenarios

In anticipation of the future multi-constellation and multi-frequency signals, the number of ranging sources available for positioning will significantly increase. This development will improve the positioning performance and thus will expand the application of satellite navigation. Therefore, RAIM-based GNSS could be used for more demanding applications such as approach with vertical guidance (APV)-I or APV-II approaches. However, with a large number of ranging sources, one can no longer assume that the probability of failure for more than one satellite with a certain timeframe is negligible. This paper proposed a fast RAIM algorithm based on dichotomy, named DT-RAIM (DichoTomy based RAIM) in this paper. DT-RAIM is based on conventional Least Squares Residuals (LSR) method to detect faults and the comparison between estimated ranges and measurement pseudo-ranges to identify the faulty satellites, which is similar to the Range Comparison RAIM algorithm. This algorithm can identify two faults and single fault very quickly as LSR, because that it is not necessary to ransack all the subsets of that omit one or more or four satellites.