Understanding PHMI for Safety of Life Applications in GNSS

摘要

Future satellite navigation systems (like Galileo) intend to provide safety-of-life services, or at least a form of integrity information. Integrity is characterized by the Probability of Hazardously Misleading Information, which is the probability that a user might exceed a certain error level (either fixed are variable). This definition, however, is incomplete, as it does not specify what is assumed to be known when computing this probability. The goal of this work is to offer an interpretation of the PHMI, point out some of the difficulties encountered in the proof of safety, and finally suggest possible future changes in the system design to mitigate these difficulties.