ARAIM Test Statistic Correlation

The requirement for continuity risk due to the false alarm of ARAIM based fault monitoring has been outlined in earlier works for ARAIM development [1]. However, the expected risk comes from an underlying conservative assumption that the correlation between multiple monitors for fault detection is negligible. Thus this paper examines the influence of the cross-correlation across ARAIM solution separation tests on the false alarm probability of the monitoring. A higher fidelity methodology to evaluate the false alarm probability based on highly correlated fault detection tests is presented. A preliminary assessment of ARAIM false alarm performance is carried out based on the proposed method. It is shown that the false alarm rate can be reduced by up to approximately 50% of the previously defined requirement (i.e., 10(-6)) when the cross-correlation amongst monitor test statistics is considered. Despite such improvement, the current ARAIM implementation appears to be not over-conservative.