# Initial Positioning Assessment of BDS New Satellites and New Signals
## 6 Conclusions  
With the official start of BDS-3 service, BDS has become a global navigation satellite system and more users can now benefit from BDS-only or BDS-combined multi-GNSS positioning. In this paper, we comprehensively assess the system status and the global positioning performance of BDS. Results show that:  
1. With the contribution of new BDS-3 satellites, the global average number of BDS satellites increases from 5.1 to 10.7, thus the global position dilution of precision value would improve. According to analysis, the average position dilution of precision availability is around 98.84%, which meets the open service performance standard of BDS.
2. Signal in space range error of the current BDS constellation is 0.83 m. For BDS-3 satellites, it shows a 0.71 m performance, which is much better than BDS-2. After removing some BDS-3 satellites tracked by a few stations, the signal in space range error of BDS-3 is competitive with GPS and Galileo. We believe that with more BDS-3 satellites in space and the improvement of timing group delay accuracy, the overall signal in space range error of BDS would further improve.
3. For single point positioning performance on the B1I frequency, with a global RMS of accuracy at 1.1 m in horizontal and 2.2 m in vertical, BDS shows a similar accuracy with GPS. Comparing with BDS-2, BDS-3 greatly improves the positioning accuracy and service area of BDS. For the new B1c signal, it shows a similar performance in positioning with B1I. While for B2a, the positioning accuracy is much worse, which may come from the inaccurate precision of BDS ionosphere correction. Meanwhile, observation noise on B1c and B2a is much better than B1I.
4. BDS-3 also benefits real-time kinematic users in ambiguity dilution of precision and real-time kinematic performance in positioning accuracy and reliability.  
To conclude, with a better signal in space range error and better position dilution of precision, PNT performance of BDS-3 will greatly improve in comparison with BDS-2, making BDS-3 a competitive global GNSS system. For the assessment of BDS signal in space range error, WUM final orbit and clock products are used. However, due to the still limited availability of BDS-3 tracking data, current precision of BDS-3 post-processed orbit and clock products are still lower than other GNSS systems. More precise products may be applied for BDS signal in space range error assessment in the future. Meanwhile, assessment of BDS-3 precise point positioning performance can also be conducted using the more precise products. With more stations tracking the B2a signal, it is expected that timing group delay accuracy would also improve.  
[PERSON] conceived the research framework; [PERSON] analyzed the data wrote the manuscript, [PERSON] and [PERSON] reviewed and revised the manuscript; [PERSON] collected the data and analyzed part of the data. This research was funded by National Natural Science Foundation of China (No. 41874042 and No. 11673050) and Opening Project of Shanghai Key Laboratory of Space Navigation and Positioning Techniques (No. KFKT_201706). We thank the GNSS observation data and products provided by IGS. The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Baseline**} & \multirow{2}{*}{**System**} & \multicolumn{2}{c}{**RMS**} & \multicolumn{2}{c}{**95\%**} \\ \cline{3-6}  & & **Horizontal** & **Vertical** & **Horizontal** & **Vertical** \\ \hline \multirow{2}{*}{20 m} & BDS-2-only & 0.0017 & 0.0038 & 0.0033 & 0.0074 \\  & BDS-2+BDS-3 & 00013 & 0.0028 & 0.0023 & 0.0054 \\ \hline \multirow{2}{*}{\(10\) km} & BDS-2-only & 0.0190 & 0.0352 & 0.0376 & 0.0682 \\  & BDS-2+BDS-3 & 0.0122 & 0.0252 & 0.0240 & 0.0470 \\ \hline \hline \end{tabular}
\end{table}
Table 6: RTK performance of BDS-2-only and BDS-2+3 for 20 m baseline and 10 km baseline (in meter).