基于低轨星座增强的北斗系统RAIM可用性分析

介绍基于残差的RAIM模型及基于单故障假设的保护水平计算方法，分析信号波束角与低轨信号高度遮蔽角之间的关系，提出以保护水平改善值和保护水平改善比作为低轨星座完好性增强的评价指标。同时，基于北斗系统与低轨星座的仿真数据，分析高度遮蔽角和等效误差水平对低轨星座增强的北斗系统保护水平和RAIM可用性的影响。结果表明，低轨星座的高度遮蔽角和等效误差水平越低，对导航系统保护水平和RAIM可用性的增强效果越好。

Analysis of RAIM Availability Based on LEO-Augmented BDS

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.