Using Kriging to Optimize WAAS Performance Over the Entire Solar Cycle

N. Pandya, F. Sheng, O. Castaneda, H. Jeong, N. Haveman, D. Goble

Abstract:	The Wide Area Augmentation System (WAAS), an augmentation of the Global Positioning System (GPS), measures ionospheric slant delays using dual frequency receivers in a network of reference stations throughout North America to compute and broadcast a vertical Ionospheric Grid Delay (IGD) and its associated integrity bound, the Grid Ionospheric Vertical Error (GIVE) at a set of Ionospheric Grid Points (IGPs). The GIVEs are used in receiver computations and significantly determine the availability of navigation services. Since the initial fielding beginning in July 2003, WAAS has computed the vertical delay estimate and the integrity bound at each IGP using a planar fit based on neighboring measurements. In a recent WAAS release, fielded in October 2011, the IGDs and the GIVEs at the IGPs are computed using kriging estimation. Various tunable ionospheric model parameters exist in the kriging algorithm. These parameters were optimized over the full range of possible ionospheric behaviors: from nominal to storm ionosphere, and from solar maximum to solar minimum. This paper documents the methodology, implementation, and analysis for the trade study that optimized kriging algorithm performance for the range of ionospheric behaviors over the entire solar cycle. A set of 64 GIVE algorithm models with varying kriging and irregularity detector parameters were traded over a 14 day data set spanning the range of ionospheric behaviors. A final set of GIVE algorithm kriging parameters was determined through the trade study that dramatically improved system availability performance and increased system robustness against storm ionospheric activity while maintaining nominal ionospheric performance. The performance improvement is shown for a set of five recent storm days.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	1310 - 1333
Cite this article:	Pandya, N., Sheng, F., Castaneda, O., Jeong, H., Haveman, N., Goble, D., "Using Kriging to Optimize WAAS Performance Over the Entire Solar Cycle," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 1310-1333.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In