Integrity Risk under Temporal Correlation for Horizontal ARAIM (H-ARAIM)

Kurzfassung

Integrity requirements for safety-critical Global Navigation Satellite System (GNSS) applications, such as in civil aviation for the non-precision approach through precision approach, are defined in a per hour or per approach (i.e., 150s) basis by the International Civil Aviation Organization (ICAO). This paper presents a novel methodology for mapping of such operational requirements to the specific risk at an algorithmic level for advanced receiver autonomous integrity monitoring (ARAIM), in particular horizontal ARAIM (H-ARAIM). We thoroughly evaluated the actual risk over time by performing extensive first-order Gauss Markov Process Monte Carlo runs for the propagation of time-correlated position errors and test statistics over one hour exposure time and accounting for multiple events of loss of integrity over the time interval. A comparison of the risk over time and the risk for a single epoch leads to the number of effectively independent samples. The current integrity equation was modified using the number such that specific risk requirement is allocated to a single sample for the determination of the protection level (PL). This study also examined the impact of the modified risk allocation on the existing fault detection and exclusion (FDE) algorithm by conducting H-ARAIM availability simulations and by comparing the results based on the newly proposed method with that obtained using the existing single sample-based risk allocation. In our preliminary assessment, little impact on the global availability (availability loss of approximately up to 1%) of the inflated terms of the integrity equation due to the number of valid samples was found.