RAIM method for improvement on GNSS reliability and integrity

With the potential of global navigation satellite system (GNSS) to be the sole-means in civil aviation and other navigation fields, integrity and related techniques become more important among which many researches focus on receiver autonomous integrity monitoring (RAIM) referring to independent integrity monitoring of GNSS without any external assistant navigation facilities. Therefore, the performances of RAIM have to be studied in order to assure the measurements quality. Usually, RAIM algorithm includes two parts: one is detecting existence of the faulty and the other is isolating the identified faulty SVs. Many researches have been done with the detecting algorithm and isolating algorithm, however, these two parts have close relationship with each other and affect the performance mutually through some key parameters. A RAIM method is proposed to assure the reliability based on mutual effect among the key parameters. Basic integrity monitoring requirements and RAIM requirements are introduced to satisfy different mode during aviation. Then key statistics are studied in RAIM algorithm, subsequently, it is found there are mutual constrains among false alarm rate, detection rate, positioning standard deviation in both detecting procedure and isolation procedure, so do non-central statistics and geometry. Reliability of the monitoring performance is studied from availability, internal and external reliability, and mutual reliability besides related factors being affected by real-time constellation geometry. The proposed RAIM method can better assure the availability and reliability theoretically. Related simple simulations are carried out and analyzed to prove the mutual detecting method primarily.