Evaluation of advanced receiver autonomous integrity monitoring for vertical guidance using GPS and glonass signals [electronic resource]
Keywords: Electrical Engineering.

The Global Navigation Satellite System (GNSS) environment has experienced two major transformations. First, fully operational constellations, including the United States Global Positioning System (GPS) and Russian Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS), are in the middle of modernization plans. Specifically, these core constellations will transmit new signals in new frequencies. Second, two more major GNSS constellations are being launched and will be fully operational in the near future. They are the European Galileo and Chinese Beidou systems. The new constellations' navigation signals will be transmitted in multiple frequency bands as well. Therefore, GNSS users will experience more signals and more satellites in the next five to ten years. In addition, these new signals will be available for civil aviation navigation systems. Signals in dual frequencies allow receivers to mitigate the pseudorange errors originating from the ionosphere. Moreover, more satellites and multiple constellations provide users with better accuracy and position estimates. Through these advantages, we can expect performance improvement in the navigation systems in terms of accuracy, robustness, and integrity. Specifically, these advantages would lead GNSS receivers to the possible use of Advanced Receiver Autonomous Integrity Monitoring (ARAIM), which is an extension of Receiver Autonomous Integrity Monitoring, which has been in use in civil aviation for over twenty years for horizontal guidance. ARAIM would extend RAIM to more demanding operations, in particular vertical guidance in landing approaches. Hence, several ARAIM algorithms have been proposed and studied in order to achieve global coverage of LPV-200 approaches, which guide an aircraft down to altitudes of 200 feet. The main purposes of this thesis are to introduce the multi-constellation ARAIM algorithm and its tool, and present extensive evaluation work of the multi-constellation ARAIM tool using real GPS and GLONASS signals. The first part of this thesis explains the navigation requirement to support LPV-200 approaches and specifies the threats that might lead the navigation function into a hazardous situation. ARAIM is designed to guarantee system integrity and assures that the navigation system is operating appropriately. In this chapter the requirements in terms of positioning performance (accuracy), integrity, continuity, and availability are specified through the probability of hazardously misleading information (PHMI), the false alert probability, the Vertical Position Error (VPE), and the Vertical Protection Level (VPL). According to LPV-200 requirements, any situation that leads to not meeting the requirements are considered as a threat. A threat can be caused by system status (faults), adverse weather, and intentional radio frequency interference. This thesis mostly focuses on faults within the navigation system, and describes what causes GNSS faults as well as their effects on a system. The second part of this thesis describes the ARAIM user algorithm including the characterization of satellite ranging error, fault detection and exclusion, and computing the VPL. The error in the range measurement is the sum of error components and these errors are modeled as a random variable and a bias. The first section specifies how to model each error component with given satellite pseudorange. The second section describes the concept and architecture of the multi-constellation ARAIM algorithm. Multi-constellation issues will be addressed as well. The third part of this thesis demonstrates the results of the evaluation of multi-constellation ARAIM. In order to assure possible use of multi-constellation ARAIM, it is necessary to test this algorithm extensively with real GNSS measurements and navigation data. The results using real GPS and GLONASS signals is demonstrated under a single satellite fault, multiple satellite faults, and a constellation fault assumption. The results presented in this thesis show that multi-constellation ARAIM could be used for safety-of-life applications, specifically LPV-200 approaches.