Cross-correlation effect of ARAIM test statistic on false alarm risk

Abstract : The requirement for ARAIM continuity risk due to the monitor false alarm has been outlined in earlier works for ARAIM development (WG-C in ARAIM technical subgroup milestone 3 report, 2016). However, the expected continuity risk comes from an underlying conservative assumption that the correlation between multiple monitors for fault detection is negligible. Thus, we investigate the effect of the cross-correlation across ARAIM solution separation tests on the monitor false alarm probability (PFA) by presenting a higher fidelity methodology to evaluate the PFA based on highly correlated fault detection tests. We carry out a preliminary assessment of ARAIM false alarm performance by using the proposed method. It was found that considering the cross-correlation among monitor test statistics reduces the predicted PFA by up to approximately 50% of the predefined requirement (e.g., 10−6) when triple satellite faults were considered. Despite such improvement, the baseline ARAIM implementation does not appear to be overly conservative.