# PPP and PPP-AR Kinematic Post-Processed Performance of GPS-Only, Galileo-Only and Multi-GNSS
## 4 Discussion and Conclusions  
In this paper we investigated the performance (in term of repeatability) of kinematic PPP and PPP-AR positioning using GPS, Galileo and combined measurements of the two systems on a global network.  
The Galileo-only PPP-AR solution performance repeatability reaches 14 mm in horizontal direction and 31 mm in vertical direction. This level is of similar order of magnitude and just below the GPS-only solution one. It is expected that once the Galileo constellation is complete, the accuracy of Galileo-only PPP and PPP-AR will improve relative to today (due to the addition of four more satellites and to the availability of receiver antenna calibration for Galileo L5 frequency).  
The Multi-GNSS solutions for both PPP and PPP-AR give much better results in term of repeatability than both systems used separately (we observe a gain in repeatability of around 30% in horizontal and in vertical directions); and this even though the Galileo-only solutions are by little not better than the GPS-only solutions. This is logically explained by the increased number of measurements and the highest satellite geometry diversity in the Multi-GNSS solutions relatively to the single systems ones (with only one inter-system bias parameter added). This result proves also that despite the unavailable receiver's antenna patterns for the E5 Galileo frequencies used in this study, the two systems are already compatible at the sub-centimeter level. We assume, as a consequence, that parameters that are highly correlated such as the vertical components, the tropospheric ZTD parameter and the station clocks are more de-correlated in the Multi-GNSS solutions than in single-systems ones.  
The best repeatabilities observed in this study for a 300 s dynamic Multi-GNSS GPS + GAL PPP-AR solution reach less than 3 mm in horizontal direction and 7 mm in the vertical one for the BRUX receiver. The global network statistics are a little larger with 8 mm in horizontal and 17 mm in vertical directions. For the global network, no particular geographical pattern has been seen among the 50 stations used.  
These results show that Galileo can really contribute to Multi-GNSS precise positioning and improve the best solutions obtained today with GPS. Scientific, geodetic and geophysical applications can already benefit from the combined processing of GPS and Galileo observations.  
Conceptualization, G.K., S.L. and F.P.; methodology, G.K.; software, S.L.; G.K. writing--original draft preparation, S.L. and F.P.; writing--review and editing.  
This research received no external funding.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Global** & **Mode** & **East (mm)** & **North (mm)** & **Up (mm)** \\ \hline \multirow{2}{*}{Galileo} & PPP & 17.0 & 14.6 & 33.1 \\  & PPP-AR & 13.7 & 12.2 & 30.8 \\ \hline \multirow{2}{*}{GPS} & PPP & 11.8 & 9.4 & 26.0 \\  & PPP-AR & 9.3 & 8.3 & 24.0 \\ \hline \multirow{2}{*}{GPS + Galileo} & PPP & 7.9 & 6.1 & 17.2 \\  & PPP-AR & 6.7 & 5.6 & 16.8 \\ \hline \end{tabular}
\end{table}
Table 8: Global RMS of 1-\(\sigma\) values for PPP and PPP-AR for the entire network examined.  
**Acknowledgments:** All authors would like to acknowledge the work of [PERSON] and [PERSON] for their work changing the EXE-PPP and the GINS software. These were extensively used for the experiments of this article. In addition, fruitful discussions with [PERSON] and [PERSON] were very much appreciated.  
**Conflicts of Interest:** The authors declare no conflict of interest.