From the pseudo-range overbounding to the integrity risk overbounding
Résumé
The advantages of a navigation system that can monitor its own integrity are obvious. All GNSS integrity monitoring methods may be broadly divided into two classes: “active integrity methods” and “passive integrity methods”. The active integrity methods, like ARAIM, are very efficient in the case of unbounded GNSS channel degradations. However, nowadays even bounded degradations of the pseudo-range measurements lead to an unacceptable additional bias of the users fix, due to reduced alarm limits. In such a case, the solution consists in the passive integrity method, which is called “overbounding”. The overbounding approach allows all pseudo-range measurements without rejection. The idea of the approach is to define conservative bounds (overbounds) for the cumulative distribution function (CDF) of pseudo-range errors in order to get a conservative bound for the integrity risk.