BIE using multivariant t-distribution and the iFlex method for GNSS PPP

Viet Duong, Suelynn Choy, Chris Rizos

Peer Reviewed

Abstract:	Reliable ambiguity resolution is the key to obtaining centimetre-level accuracy in high precision GNSS positioning techniques such as Real-Time Kinematic (RTK) and Precise Point Positioning (PPP). In this contribution, an approach for partial ambiguity resolution based on the best integer equivariant estimator using the multivariant t-distribution (BIE-td) is proposed and compared against the iFlex method proposed by the Trimble Navigation company. A 31-day set of GNSS measurements, collected in 2018 from 17 globally distributed GNSS continuously operating reference stations (CORS), were processed to determine the best-fit distribution for the GNSS measurements. It is found that the t-distribution with three degrees of freedom provides a better fit compared to the Gaussian distribution. Finally, an additional 7-day set of GNSS measurements, collected in 2019 from the same CORS, confirms that the positioning performance using the BIE-td and iFlex method using Laplace and Maxmin function is comparable, with a similar positioning accuracy for both the horizontal and vertical coordinate components. Significantly, both the BIE-td and iFlex methods using Laplace (or Maxmin) outperform the BIE using the Gaussian function. Although the iFlex method reduces computational burden compared to the BIE-td, its function such as Laplace or Maxmin is not mathematically rigorous, and hence the BIE-td method is recommended.
Published in:	Proceedings of the 2021 International Technical Meeting of The Institute of Navigation January 25 - 28, 2021
Pages:	454 - 464
Cite this article:	Duong, Viet, Choy, Suelynn, Rizos, Chris, "BIE using multivariant t-distribution and the iFlex method for GNSS PPP," Proceedings of the 2021 International Technical Meeting of The Institute of Navigation, January 2021, pp. 454-464. https://doi.org/10.33012/2021.17869
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