Optimal risk allocation for BDS/GPS advanced Receiver Autonomous Integrity Monitoring

Receiver Autonomous Integrity Monitoring (RAIM) is a sensor level integrity monitoring system which is essential for safety-of-life applications. The increased number of satellites in view with BDS/GPS has drawn interest in Advanced RAIM (ARAIM) to provide vertical guidance for aircrafts. In the baseline ARAIM algorithms, the continuity risk under fault-free hypothesis is allocated evenly to each hypothesis to obtain the detection threshold. However, the BDS constellation is different from GPS constellation in both the satellite geometry and the prior probability of satellite fault. In this paper, the influence of both satellite geometry and prior fault probability on the integrity risk is analyzed. The optimal risk allocation for BDS/GPS ARAIM is proposed to reduce the integrity risk with the continuity risk within the requirement. The experimental results demonstrate the effectiveness of our proposed algorithm over the baseline ARAIM methods in reducing the integrity risk.