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A Two-Step Regional Ionospheric Modeling Approach for PPP-RTK.
Zhenyu Xu1, Changsheng Cai1,2, Lin Pan1
1School of Geosciences and Info-Physics, Central South University, Changsha 410083, China.
Sensors (Basel, Switzerland)
|April 13, 2024
Summary
This study introduces a new two-step ionospheric modeling method for precise point positioning/real-time kinematic (PPP-RTK) to improve positioning accuracy. The Polynomial Fitting Model combined with Kriging Interpolation (PFM/KI) significantly reduces ionospheric delay errors and speeds up convergence.
Area of Science:
- Geodesy and Geomatics
- Atmospheric Science
- Satellite Navigation
Background:
- Precise Point Positioning/Real-Time Kinematic (PPP-RTK) relies on accurate ionospheric delay corrections for rapid convergence.
- Current ionospheric models in PPP-RTK often neglect residual ionospheric delays, impacting positioning accuracy.
- Existing methods primarily focus on the trend term of ionospheric total electron content (TEC) variations.
Purpose of the Study:
- To develop and validate a novel two-step regional ionospheric modeling approach for enhanced PPP-RTK performance.
- To improve the accuracy of ionospheric delay corrections by modeling both trend and residual TEC variations.
- To assess the impact of the proposed model on PPP-RTK convergence speed and positioning accuracy.
Main Methods:
- A two-step modeling approach combining a Polynomial Fitting Model (PFM) for the trend term and Kriging Interpolation (KI) for the residual term of TEC variations.
- Validation using datasets from Continuously Operating Reference Stations (CORSs) in Hunan Province, China.
- Comparison against a single PFM method and a PFM combined with Inverse Distance Weighting Interpolation (IDWI).
Main Results:
- The PFM/KI method achieved an average root mean square (RMS) error of 1.8 cm for modeled ionospheric delay, outperforming PFM (48% improvement) and PFM/IDWI (23% improvement).
- PPP-RTK using PFM/KI converged to 1.3 cm horizontal accuracy in 1.8 minutes and 2.5 cm vertical accuracy in 4.0 minutes.
- Convergence times were reduced by 18% (horizontal) and 9% (vertical) compared to PFM, and 14% (horizontal) and 5% (vertical) compared to PFM/IDWI.
Conclusions:
- The proposed two-step PFM/KI ionospheric modeling significantly enhances the accuracy of ionospheric delay corrections in PPP-RTK.
- This improved modeling leads to faster convergence times and higher positioning accuracy in PPP-RTK applications.
- The PFM/KI method offers a superior alternative to existing ionospheric modeling techniques for real-time kinematic positioning.
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