A Comprehensive Integrity Verification Architecture for On-Airport LAAS Category III Precision Landing

Sam Pullen, Boris Pervan, Per Enge, and Bradford Parkinson

Abstract:	Future Local Area Augmentation System (LAAS) architectures will most likely be constrained to lie on airport property. Such a system must provide protection against rare events in the GPS Signal in Space (SIS) that pose danger to airborne users conducting Category III precision landings. By allowing the aircraft to combine ground integrity information with its own checks in order to make the final integrity decision, LAAS should be able to meet the performance, integrity, continuity, and availability (PICA) requirements for this application. Stanford has proposed a solution that includes inter- nally redundant airport pseudolites (APL’s) and a set of differential reference and monitor receivers connected to a central processing facility. Ground monitoring in- cludes comparisons of the code and carrier measurements at spatially separated monitors. Satellites and corrections with excessive discrepancies are eliminated, and the rest are uplinked to the aircraft as valid for use. Aircraft receiving the LAAS message compute the achievable bound on vertical error that determines whether approaches can commence or continue. Aircraft also perform space segment and redundant-channel consistency checks during their approach to detect any remaining errors in the Signal-in-Space (SIS). The elements of this integrity architecture should combine to provide acceptable PICA availability for precision landings. Further refinements will focus on detailed specification of the aircraft VPL probability computation and mitigation steps, APL self-monitoring, and the use of Signal Quality Monitoring (SQM) to improve ground and airborne receiver robustness.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	1623 - 1634
Cite this article:	Pullen, Sam, Pervan, Boris, Enge, Per, Parkinson, Bradford, "A Comprehensive Integrity Verification Architecture for On-Airport LAAS Category III Precision Landing," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 1623-1634.
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