Abstract:We introduce the residual-based RAIM model and protection level calculation method based on the single-fault assumption, analyze the relationship between the beam angle and defilade angle of LEO satellites, and propose the improvement value and improvement ratio of protection level as the integrity enhancement index of LEO constellations. Based on the simulation data of BDS and LEO constellation, we analyze the influence of defilade angle and equivalent error level on protection level and RAIM availability. The results show that the lower the defilade angle and equivalent error level, the better the enhancement effect on protection level and RAIM availability.