Investigation of Extending Receiver Autonomous Integrity Monitoring (RAIM) to Combined Use of Galileo and Modernized GPS

Young C. Lee

Abstract:	The United States has plans to modernize GPS, and Europe has plans to implement the new Galileo system. By exploiting the large number of satellites and new signals from both systems, it might be possible to extend Receiver Autonomous Integrity Monitoring (RAIM) to achieve much smaller alert limits. A possible application is instrument approach with vertical guidance. This paper provides a preliminary analysis of an application to a specific type of instrument approach designated LPV, which has a vertical alert limit (VAL) of 50 m. Results suggest that the application could be feasible, but there are some important conditions, including an assumption that the magnitude of the pseudorange error resulting from any fault affecting multiple satellites can be bounded to several times the standard deviation of the nominal ranging error. A case for bounding the worst-case multiple-satellite faults would probably require a detailed failure mode and effects analysis (FMEA) of each future constellation. For lack of such a validation, it is not yet possible to make an unequivocal assessment of the feasibility, but the concept may still be worth pursuing.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1691 - 1698
Cite this article:	Lee, Young C., "Investigation of Extending Receiver Autonomous Integrity Monitoring (RAIM) to Combined Use of Galileo and Modernized GPS," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1691-1698.
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