Advanced RAIM Based on Inter-Constellation Comparisons to Detect Consistent Faults for LPV-200

Y.C. Lee, T. Cashin

Abstract:	With the prospect of a much improved navigation capability for civil aviation in the 2020 to 2025 time frame from multiple-frequency civil signals and possibly a larger number of satellites, the FAA?s GNSS Evolutionary Architecture Study (GEAS) Panel is evaluating Receiver Autonomous Integrity Monitoring (RAIM) as one of the major GPS-based architectures that could provide robust LPV-200 service worldwide circa 2020–2025. However, an early GEAS analysis showed that, even when a perhaps somewhat optimistic set of assumptions is used, RAIM cannot provide a worldwide LPV-200 service with the desired availability in this time frame without a significantly larger number of operating satellites than expected from the currently planned modernized GPS constellation of 27 satellite vehicles (SVs) in nominal orbital positions. For this reason, RAIM using multiple constellations is being given serious consideration. Like modernized GPS, other Global Navigation Satellite System (GNSS) constellations currently under development plan to provide dual-frequency transmissions that would make their user range accuracy comparable to that for modernized GPS. Therefore, using GPS and other constellations in combination can provide much more accurate position solutions and integrity with higher availability/coverage. Moreover, it requires combined constellations to be able to handle consistent faults viewed as credible. This paper first shows the limitations of the single-constellation ARAIM algorithm developed by GEAS in dealing with consistent faults. The paper then analyzes how well ARAIM based on inter-constellation comparisons can perform in the presence of consistent faults using multiple constellations.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	272 - 284
Cite this article:	Lee, Y.C., Cashin, T., "Advanced RAIM Based on Inter-Constellation Comparisons to Detect Consistent Faults for LPV-200," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 272-284.
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