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

  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.