Credibility Monitoring Research of BDS Based on LEO/INS

The reliability of satellites navigation system has always been the focus of international community, the risks of integrity and hostile interference are important factors affecting the reliability of airborne satellites navigation system. LEO satellites with advantages of running in low orbits, having rapid change of satellite geometry and strong anti-interference capability of satellite signal, can significantly enhance the credibility of BDS. But when most or even all satellites are spoofed, LEO satellites and BDS navigation system can hardly detect and recognize faults. Hence, we add inertial navigation system as an independent navigation source to the whole system and propose a credibility algorithm based on inertial navigation system, combining INS with all visible satellites to detect and recognize fault satellites in more directions, constructing chi-square test statistics based on the Kalman Filter innovation sequence on the basis of satisfying the need of integrity. The simulation results show that LEO/INS-aided system can detect and recognize fault satellites in more than one directions. Under the indexes of 90% integrity default detection rate and recognition rate, compared with single BDS system, the two indexes of the INS-aided system improve about 20% and 40% respectively. For hostile faults, the LEO satellites can significantly improve the anti-spoofing performance of integrated navigation system, the detection rate increases about 25% and the recognition rate increases more than 30%.