Pseudo-range errors and the integrity risk overbounding
Résumé
For many safety-critical GNSS applications, even bounded degradations of the pseudo-range measurements can lead to an unacceptable additional bias of the users fix, due to reduced alarm limits. In such a case, a reasonable solution consists in the passive integrity method, which is called “overbounding”. In contrast to the (A)RAIM methods, the overbounding approach allows all pseudo-range measurements without rejection. The idea of this approach is to define conservative bounds (overbounds) for the cumulative distribution function (CDF) or probability density function (PDF) of pseudorange errors in order to get a conservative bound for the integrity risk. The original contribution of this paper is twofold. First, we propose two new conservative bounds for the integrity risk in the horizontal plane. Second, we calculate the impact of the pseudo-range errors autocorrelation on the conservative bounds for the vertical/horizontal integrity risks.