BDS/LEO ARAIM subset selection method

In recent years, multi-GNSS have developed vigorously, and the idea of using low earth orbit (LEO) communication satellites for navigation has gradually become a reality. Since a single constellation cannot meet the performance requirements of LPV-200 alone, LEO constellation with navigation payload can be used as a navigation system to perform Advanced Receiver Autonomous Integrity Monitoring together with BDS constellation in order to meet the requirement of LPV-200. After LEO constellation is added, the number of visible satellites increases significantly, resulting in doubling of the number of subsets. In order to reduce the computational load, a subset selection method based on satellite selection and fault mode division has proposed in this paper. According to the regional enhancement feature of BDS, an area filtering module was added to divide regions with different performance. Areas with good performance have enough redundant observations. In these areas, the satellite selection method was used to select appropriate number of satellites to participate in the positioning solution. In addition, the orbit-based fault mode division method was used for these areas which aggregated the fault subsets on the same kind of orbits. For areas with poor performance, all visible satellites were used for positioning solution and the baseline MHSS was used for subset calculation. Simulation results showed that after using the new algorithm, the number of subsets has reduced by 43.6%, the simulation time has slightly improved and the availability coverage basically unchanged.