Comparative Ionosphere Electron Content Estimation Method in SBAS Performances

P. Alleau, G. Buscarlet, S. Trilles, M. Van Den Bossche, J. Bigot

Abstract:	The activities on ionosphere delay estimation and associated covariance have known a renewed interest since 2011 when the increase of solar activity has caused strong performance disturbance of both operational Safety of life Satellite Based Augmentation Systems, WAAS and EGNOS. Different techniques are used depending the service provider. EGNOS has implemented Triangular Interpolation (TRIN) model (A.J. Mannucci et al. of ION GPS-93) whilst WAAS used Krieging algorithm methods. These methods react differently as function of the dynamics of the ionosphere, resulting in different level of performances. Moreover limitations are already well identified. The linear ionosphere spatial evolution over a facet is a strong assumption regarding TRIN model and, the Krieging method need of semi-variogram estimation that is independent from spatial correlation anisotropy. The purpose of the paper is to review and prototype different ways of computing ionosphere estimation delay and associated covariance. A review of state of art allowed to select methods. We consider on the on hand a compressed sample method aiming to decompose signal over a suitable orthogonal bases in very few component, and on the other hand spline techniques. Both methods have been analysed and roughly assessed. Comparisons of the performances are performed with respect to TRIN and Krieging methods based on the analysis of the temporal and spatial distribution of ionosphere pierce points (IPP) - and associated L1 ionosphere delays. In a first time we present each method and their applications in the interpolation ionosphere context. In a second time we found out some particular signature for each method in function of ionosphere dynamic layer by analysing accuracy, integrity and availability of the system. In a last time we provide a table of results that summarise the performances reached for each method. In the paper we present results and recommendation from this experimentation in order to identify the method providing the best behavior in case of nominal and strong ionosphere condition.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2523 - 2532
Cite this article:	Alleau, P., Buscarlet, G., Trilles, S., Bossche, M. Van Den, Bigot, J., "Comparative Ionosphere Electron Content Estimation Method in SBAS Performances," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2523-2532.
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