三种典型低轨增强星座与北斗系统联合应用的RAIM性能分析

RAIM Performance Analysis of Three Typical Low-Orbit Augmentation Constellations Combined with BDS Applications

接收机自主完好性监测(receiver autonomous integrity monitoring,RAIM)是终端用户高可靠导航定位的保障,低轨卫星的发展为完好性监测带来新的机遇,然而不同低轨星座增强下的终端RAIM性能可能会存在显著差异。基于高轨道倾角(80颗)、中轨道倾角(120颗)和混合轨道倾角(168颗)3种典型的低轨星座,系统评估了低轨卫星增强下的北斗卫星导航系统(BeiDou navigation satellite system,BDS)RAIM可用性及故障检测效果。仿真计算结果表明:对于高纬区域,高轨道倾角增强下的RAIM可用性效果最好,而在中、低纬区域,中轨道倾角星座增强下的RAIM可用性效果最优;在全球范围内,高轨道倾角、中轨道倾角和混合轨道倾角星座增强下非精密进近阶段的RAIM可用性较BDS分别提升30.5%、29.0%和41.0%。由此可知,由不同轨道倾角组成的混合星座可较好地弥补可视卫星在空间覆盖上的缺陷,其全球RAIM可用性增强效果最优,增强下的RAIM可检测到的最小伪距偏差较之前平均减小33.3 m。

Objectives:Receiver autonomous integrity monitoring(RAIM)is the guarantee of highly reliable navigation and positioning for terminal users,and the development of low earth orbit(LEO)satellites brings new opportunities for integrity monitoring.However,there may be significant differences in terminal RAIM performance under different LEO constellation enhancements.Methods:We systematically evaluate the RAIM availability and fault detection effects of the BeiDou navigation satellite system(BDS)under LEO satellite augmentation based on three typical LEO constellations:High-inclination(80 satellites),mid-inclination(120 satellites)and mixed-inclination constellations(168 satellites).Results:The simulation results show that the RAIM availability effect under the high-inclination constellation enhancement is most effective in high-latitude regions,while in the mid-and low-latitude regions,the RAIM availability effect under the mid-inclination constellation enhancement is the best.After adding the high-inclination,mid-inclination,and mixed-inclination constellations,the global RAIM availability in the non-precision approach phase is improved by 30.5%,29.0%,and 41.0%than that of the BDS,respectively.Conclusions:It can be seen that the hybrid constellation composed of different orbital inclinations can compensate for the defects in spatial coverage of the visible satellites,and its global RAIM availability enhancement effect is optimal,and the minimum pseudorange deviation detected by the enhanced RAIM is reduced by 33.3 m compared with the previous one.