# Galileo: The Added Value for Integrity in
## 5 Experimental Results
### Positioning Results
A short time interval of the test is considered to investigate the performance of the configurations with RAIM application. reliable epochs, as shown in the central box of Figure 12. In order to have a fair comparison between GPS/Galileo and GPS only solutions, the CDFs are computed using only the reliable epochs in the lower box of Figure 6:0 The enhancements due to the Galileo measurements clearly emerge from the comparison. The horizontal position scatter plots of the configurations analyzed are shown in Figure 6:1 In Figure 13a, the dispersion of the configurations without RAIM are plotted, whereas the horizontal positions provided by the configurations with the RAIM application are shown in Figure 13b. From the figures, the improvements of the RAIM application are evident: the clouds in Figure 13b are more concentrated than the ones in Figure 13a. The benefits of the Galileo measurements' introduction are even more clear: in both cases, the green clouds are more concentrated than in the yellow ones. Figure 6:2 Vertical position error as a function of time. Upper box: vertical errors of the configuration without RAIM application; lower box: vertical errors of the configurations with RAIM. Figure 6:3 CDFs of the vertical position errors. Upper box: CDFs of the vertical errors computed using all epochs; central box: CDFs computed using only the reliable epochs; lower box: CDFs computed using only common epochs. The parameters used to summarize the performance of the configurations considered are the maximum, mean and SD of the horizontal and vertical errors. The parameters are computed for the four configurations and are reported in Tables 3-5. In Table 3, the parameters are computed using all available epochs; in Table 4, only reliable epochs are considered; and finally, in Table 5, only common reliable epochs are used. In all cases, the synergy between GPS/Galileo and the RAIM algorithm achieves the best performance with the lowest error values. Furthermore, in the velocity domain, data are characterized by a high SA, which is 95% in the case of GPS only: the inclusion of the Galileo measurements improves the SA by about 5%. The application of the RAIM algorithm reduces the availability of the solution, which in the GPS only case is more than halved passing from 95% to 45%; in this case, the benefit of the introduction of the Galileo observables is more evident with an enhancement of 23% with respect to the GPS-only case. The results related to the SA and RA of the velocity solution are detailed in Figure 6:4  
The number of pseudorange-rate measurements excluded from the navigation solution is plotted as a function of time in Figure 6:5 the number of exclusions is lower than in the pseudorange case; however, also in this case, the introduction of the Galileo measurements improves the redundancy of \begin{table}
\begin{tabular}{c c c} \hline \hline
**Configuration** & **SA (\%)** & **RA (\%)** \\ \hline GPS noRAIM & 95 & N.A. \\ GG noRAIM & 100 & N.A. \\ GPS RAIM & 95 & 45 \\ GG RAIM & 100 & 62 \\ \hline \end{tabular}
\end{table} 
Table 6: SA and RA of the velocity solutions. Figure 14: Integrity flag as a function of time. The flag is set to zero when it is not possible to test the reliability of the solution; one implies a reliable solution; two indicates an unreliable solution. Figure 15: Details of the velocity integrity flag around epochs where the GPS-only solution is declared unreliable. the system, enhancing the performance of the RAIM algorithm, which is able to reject a higher number of observables. The horizontal velocity errors are plotted as a function of time in Figure 17. In the upper box of the figure, the configurations without RAIM show similar performance: the introduction of the Galileo measurements provides only a slight error reduction. In the lower box, where the configurations without RAIM are considered, the benefits of the Galileo inclusion are more evident; the use of RAIM improves the performance mainly in terms of maximum errors, which are strongly reduced.