Abstract
Signal-In-Space User Range Errors (SIS UREs) are assumed to be overbounded by a normal distribution with a standard deviation represented by the User Range Accuracy (URA). The BeiDou Navigation Satellite System (BDS) broadcast URA is not compatible with the historical SIS URE performance that affects the Advanced Receiver Autonomous Integrity Monitoring (ARAIM) False Alert Probability (Pfa) and availability evaluation. This study compares the BDS broadcast and precise ephemeris from 1 March 2013 to 1 March 2017 to obtain SIS UREs. Through analyzing the statistical characteristics of the SIS UREs, we obtain the standard deviation σURE for the accuracy and continuity and σURA used for the integrity of the SIS UREs. The results show that the broadcast σURA of 2 m cannot completely overbound SIS UREs for all BDS satellites, but the σURA of 2.4 m can. Then, we use the σURA of 2.4 m to evaluate the ARAIM Pfa and availability. The results show that the Pfa may increase to 2 × 10−5 and exceed its limit by an order of magnitude. We also consider the differences between the SIS UREs of Geostationary Earth Orbit (GEO), Inclined Geo-Synchronous Orbit (IGSO), and Medium Earth Orbit (MEO). The results indicate that all Pfa values calculated by the computed σURE are less than the Pfa in the Integrity Support Message (ISM) for the worst-performing GEO satellite. The approximately 55% Pfa calculated by the computed σURE is less than the Pfa in ISM for the worst-performing IGSO satellite. Most Pfa values calculated by the computed σURE is less than the Pfa in the ISM for the worst-performing MEO satellite. For BDS satellites, the Pfa is mainly affected by σURE. When the σURA of 2.4 m is used to evaluate the availability, the computed availability is lower than the availability calculated by the broadcast σURA/σURE and the greatest degradation can reach 25%.
Highlights
Advanced Receiver Autonomous Integrity Monitoring (ARAIM) can provide global users with integrity monitoring service for vertical guidance [1]
This paper focus on analyzing the errors that arise in navigation satellites, such errors are called Signal-In-Space
In some cases, the Protection Levels by the computed σURA/σURE exceed the Alert Level (AL), but those calculated by the broadcast σURA/σURE are below the AL, which may lead to missing alert
Summary
Advanced Receiver Autonomous Integrity Monitoring (ARAIM) can provide global users with integrity monitoring service for vertical guidance [1]. The value of URE represents the standard deviation of the clock and ephemeris error used for accuracy and continuity [4]. These parameters should describe the characteristics of historical SIS. University studied GPS historical data between 2009 and 2011 Their results show that the SIS UREs characteristically vary among different GPS satellites. The results show that the average SIS UREs for the Geostationary Earth Orbit (GEO), Inclined Geo-Synchronous Orbit (IGSO), and Medium Earth Orbit (MEO) satellites are different [10] Most of these studies have analyzed the observed historical data of different constellations to describe the characteristics and accuracy of SIS UREs. there is lack of information on the effect of SIS. This paper analyzes the effects of the URA and URE on the ARAIM Pfa and availability
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