An Improved BeiDou-2 Satellite-Induced Code Bias Estimation Method

Area of Science:

• Geodesy and Geomatics Engineering
• Satellite Navigation Systems
• Signal Processing

Background:

• BeiDou-2 (BDS) satellites exhibit code multipath bias (CMB), originating from the satellite, significantly impacting precise positioning.
• Existing correction models for CMB are orbit-type dependent and use a coarse elevation node separation.

Purpose of the Study:

• To develop and validate an improved correction model for estimating and mitigating code multipath bias (CMB) in BeiDou-2 (BDS) IGSO and MEO satellites.
• To enhance the performance of precise point positioning (PPP) applications using BDS code observations.

Main Methods:

• Developed a satellite-specific CMB correction model for each BDS IGSO + MEO satellite.
• Employed a denser elevation node separation (5°) for modeling CMB variations.
• Utilized one month of BDS observations from the IGS-MGEX network for model assessment.

Main Results:

• The improved model demonstrated significant differences in CMB even for satellites of the same orbit type.
• Enhanced wide-lane (WL) ambiguity usage rate from 94.1% to 96.0%.
• Reduced WL and narrow-lane (NL) time to first fix (TTFF) for PPP ambiguity resolution (AR) from 10.6 to 9.3 min and 67.9 to 63.3 min, respectively.

Conclusions:

• The proposed satellite-specific CMB correction model with finer elevation nodes improves PPP accuracy and ambiguity resolution efficiency for BDS.
• The refined model offers a substantial improvement over traditional methods and models neglecting CMB correction.