Prototyping Advanced RAIM for Vertical Guidance

J. Blanch, M.J. Choi, T. Walter, P. Enge, K. Suzuki

Abstract:	In the next decade, the GNSS environment is going to undergo a major transformation. First, two more GNSS core constellations are expected to be launched, Galileo and Compass. When these constellations are in their final operational capability, there will be three times more ranging sources. Second, GPS and the new core constellations will broadcast signals in two frequencies L1 and L5 (E5 a or b for Galileo). These signals will be available for civil aviation, allowing users to cancel the pseudorange errors due to the ionosphere. Many studies suggest that it could be possible to achieve global coverage of vertical guidance using multi-constellation, dual frequency RAIM, under certain assumptions on the constellation performance. However, to achieve vertical guidance RAIM (which will be referred from then on by ARAIM or Advanced RAIM), it will not be sufficient to apply the current RAIM algorithms that are used for horizontal RAIM. First of all the level of safety required for horizontal RAIM is lower than for vertical guidance ( a failure to bound the error for LNAV is classified as a major (10-5) failure condition, while a failure to bound in an LPV approach is severe major (10-7).) Also, the difference between the achieved accuracy and the necessary accuracy for horizontal RAIM is very large (more than a factor of 20). This will probably be tighter for vertical guidance. For these reasons, a more careful analysis will be need before vertical guidance RAIM can be certified. All the challenges for vertical guidance RAIM are derived from this requirement. In this paper, we will examine what will be required from the constellation providers both in terms of integrity and availability. Then we will show the results of a prototype ARAIM algorithm using an extensive data set.
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:	285 - 291
Cite this article:	Blanch, J., Choi, M.J., Walter, T., Enge, P., Suzuki, K., "Prototyping Advanced RAIM for Vertical Guidance," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 285-291.
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