Abstract
Ionospheric delay is a significant error source in multi-GNSS positioning. We present different processing strategies to fully exploit the ionospheric delay effects on multi-frequency and multi-GNSS positioning performance, including standard point positioning (SPP) and precise point positioning (PPP) scenarios. Datasets collected from 10 stations over thirty consecutive days provided by multi-GNSS experiment (MGEX) stations were used for single-frequency SPP/PPP and dual-frequency PPP tests with quad-constellation signals. The experimental results show that for single-frequency SPP, the Global Ionosphere Maps (GIMs) correction achieves the best accuracy, and the accuracy of the Neustrelitz TEC model (NTCM) solution is better than that of the broadcast ionospheric model (BIM) in the E and U components. Eliminating ionospheric parameters by observation combination is equivalent to estimating the parameters in PPP. Compared with the single-frequency uncombined (UC) approach, the average convergence time of PPP with the external ionospheric models is reduced. The improvement in BIM-, NTCM- and GIM-constrained quad-constellation L2 single-frequency PPP was 15.2%, 24.8% and 28.6%, respectively. The improvement in convergence time of dual-frequency PPP with ionospheric models was different for different constellations and the GLONASS-only solution showed the least improvement. The improvement in the convergence time of BIM-, NTCM- and GIM-constrained quad-constellation L1/L2 dual-frequency PPP was 5.2%, 6.2% and 8.5%, respectively, compared with the UC solution. The positioning accuracy of PPP is slightly better with the ionosphere constraint and the performance of the GIM-constrained PPP is the best. The combination of multi-GNSS can effectively improve the positioning performance.
Highlights
Ionospheric delay effect is one of the main errors in global navigation satellite system (GNSS) positioning, navigation and timing (PNT), and it is normally several or tens of meters it can exceed 100 m under the severe ionospheric disturbances [1,2]
We present different processing strategies to fully exploit the ionospheric delay effects on multi-frequency and multi-GNSS positioning performance, including standard point positioning (SPP) and precise point positioning (PPP) scenarios
Neustrelitz total electronic content (TEC) model (NTCM)-constrained PPP solutions perform better than the broadcast ionospheric model (BIM)-constrained solutions in the E and URecmoomte pSeonns.e2n0t1s8., 10, x FOR PEER REVIEW
Summary
Ionospheric delay effect is one of the main errors in global navigation satellite system (GNSS) positioning, navigation and timing (PNT), and it is normally several or tens of meters it can exceed 100 m under the severe ionospheric disturbances [1,2]. Several ionospheric delay models can be used for real-time or post-processed applications. With the rapid development of current navigation constellations and construction of more stations, GNSS represents a new era and has wide applications all over the world In this new multi-frequency and multi-GNSS environment, observations from different signals and constellations are processed together, a consideration of the error sources is necessary and mandatory to ensure that the positioning model is consistent. In the case of the single-frequency SPP approach, the GNSS observations are corrected with existing ionospheric models to ensure a positioning accuracy of meters. The ionosphere-free (IF) combination is an effective and popular way to eliminate the first order of ionosphere delay in dual-frequency PPP [6]. Multi-GNSS combined positioning models consist of single-frequency SPP/PPP and dual-frequency PPP. A comprehensive analysis of the impact of ionospheric delay correction on multi-GNSS performances is performed
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