## 4 PPP Accuracy Evaluation
### Kinematic PPP Performance  
The mean convergence time for kinematic PPP of six combinations for each station in the east, north, and up directions is presented in Figure 11, and the mean convergence time of each combination is listed in Table 7. It can be seen that the convergence time of the Galileo solution is the shortest in the east direction, it is 23.82 min, while the shortest convergence time is the GPS-only solution in the north and up directions, with convergence times being 8.49 min and 24.4 min, respectively. For the east direction, the convergence time of the GPS-only solution is faster than that of the GLONASS-only solution, and the BDS-only solution is the longest, nearly one hour is still needed to obtain the centimeter-level position accuracy in kinematic PPP mode, whereas it is about 20 min for the GPS/QZSS solutions. Compared to the GPS-only and BDS-only solutions, the improvement of convergence time for the GPS/QZSS and BDS/QZSS solutions is 24.82%, 7.66%, 10.90%, and 11.06%, 19.94%, and 6.66% in the east, north, and up components, respectively. Compared to the static PPP, the improvement rate of convergence time for the GPS/QZSS and BDS/QZSS solutions is larger, which may be that the increased number of satellites and better geometry distribution of satellites are beneficial to the convergence of kinematic PPP. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multicolumn{3}{c}{**Convergence Time (min)**} & \multicolumn{3}{c}{**Positioning Accuracy (cm)**} \\ \cline{2-7}  & **E** & **N** & **U** & **E** & **N** & **U** \\ \hline G & 24.78 & 8.49 & 24.40 & 2.80 & 2.03 & 4.65 \\ GJ & 18.63 & 7.84 & 21.74 & 2.43 & 1.91 & 4.15 \\ C & 55.62 & 31.09 & 45.37 & 1.77 & 1.59 & 4.69 \\ CJ & 49.47 & 24.89 & 42.35 & 1.76 & 1.57 & 4.50 \\ R & 43.39 & 47.68 & 50.98 & 6.32 & 5.59 & 14.87 \\ E & 23.82 & 17.80 & 34.02 & 6.36 & 5.68 & 8.79 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Convergence time and positioning accuracy of different combination kinematic PPP. Figure 10: Positioning accuracy of static PPP solution in each station. The kinematic PPP mean positioning accuracy of six combinations for each station in the east, north, and up directions are presented in Figure 12, and the mean positioning accuracy of each combination is listed in Table 7. One can see that the GPS-only, GPS/QZSS, BDS-only, and BDS/QZSS solutions show similar positioning accuracy in three directions except for the LAUT and MIZU station, which is better than 3 cm in the three directions. The positioning performance of GLONASS and Galileo in the Asia-Pacific region is relatively poorer. The positioning accuracy of BDS presents the best performance in the east and north component, and the positioning accuracy is 1.77 cm and 1.59 cm, respectively. This is due to the launch of BDS-3 satellites, the number of BDS satellites is more than other satellite systems in the Asia-Pacific region. The positioning accuracy in the up direction of GPS shows the best performance, and it is 4.65 cm. For the east and north directions, the positioning accuracy of GPS is better than that of Galileo, whereas the GLONASS is the worst. In terms of the up direction, the positioning accuracy of BDS is better than that of Galileo, while the GLONASS is still the worst. Moreover, compared to the GPS-only solution and BDS-only solutions, the positioning accuracy of the GPS/QZSS and BDS/QZSS solutions can be improved from 2.80 cm, 2.03 cm and 4.65 cm to 2.43 cm, 1.91 cm and 4.15 cm, with the improvement being 13.21%, 5.91%, and 10.75%, from 1.77 cm, 1.59 cm, and 4.69 cm to 1.76 cm, 1.57 cm, and 4.50 cm for the east, north, and up directions, with the improvement being 0.56%, 1.26%, and 4.05%, respectively. Except for the GLONASS-only and Galileo-only solutions, the positioning accuracy of 3 cm, 3 cm, and 5 cm in the east, north, and up components for kinematic PPP can be achieved.