Solution of the Two-Failure GPS RAIM Problem Under Worst-Case Bias Conditions: Parity Space Approach

With the advent of the GPS Wide Area Augmentation System (WAAS), there is increased interest in the receiver autonomous integrity monitoring (RAIM) multiple-failure problem. This paper shows how the horizontal and vertical protection level parameters (HPL and VPL) are affected by imposing a hypothetical worst-case two-failure requirement on the RAIM system. A numerical example is presented, and a short discussion of generalizing the method to more than two failures is also given. As might be expected, the paper indicates that the HPL and VPL parameters are increased significantly with the more demanding two-failure requirement as compared with detection of a single failure.