RAIM-FDE Revisited: A New Breakthrough In Availability Performance With<scp><i>nio</i></scp><i>RAIM</i>(Novel Integrity-Optimized RAIM)

ABSTRACT: The major shortcoming of Receiver Autonomous Integrity Monitoring Fault Detection and Exclusion (RAIM-FDE) is widely recognized to be its occasional lack of availability. There have been recent proposals to better balance accuracy and integrity levels such that the horizontal integrity limit for all satellite measurement geometries is lowered thereby improving system availability in the process. This paper presents a specific methodology called nioRAIM for accomplishing the proper balancing of position accuracy with integrity. It also shows that, for the Non-Precision Approach (NPA) phase of flight where baro-aiding is available, 50 percent of the unavailable geometries derived using standard RAIM-FDE can be salvaged when using nioRAIM. This paper also shows the added complexity involved in computing the nioRAIM algorithm, but a design is presented that is still amenable to real-time computation.