## 4 System Testing and Performance
### System Deployment in the Real Scenario
* signal: this value has the greatest importance for the purpose of the research in the paper, as it shows the strength of the measured power signal in decibels. In Figure 10, they are shown to cover a range between \(-75\) dB (stronger, better signal quality) and \(-114\) dB (weaker, worse signal quality). * lat: refers to the latitude of the device used to measure the information from the 4G LTE signal, with the precision expected to be obtained from Galileo. * lon: in a similar way, this feature is used to reflect the longitude of the device used for data measurements. Note that by using latitude and longitude combined, the location of the experiments performed and how the UAV moved around that area can be known. * acc: this field refers to the expected accuracy of the measured positions or, from a different point of view, the likely positioning error to be measured. The values displayed in Figure 10 are shown in centimetres. * time: a timestamp used to show the moment when the measurement was taken. The format used is Epoch, so it can be utilized to trace the moment when flying tests were carried out. * speed: refers to the speed of the device used to calculate the measurements. The values for each piece of data collected appear in Figure 10; it must be considered that the information obtained is measured as scalar data rather than vectorial data, so only one field is provided. Measurements are taken in meters per second. * bearing: refers to the azimuth angle (defined in this context as the angle between the object and the magnetic north of the Earth) taken during the MDAS measurements (which is directly linked to those taken by the UAV on which the MDAS is installed). * alt: refers to the altitude that the MDAS was at when the measurements were taken. Figure 10 shows altitude values all well above 700 m; this is because the altitude measured takes 0 as sea level, and the testing location was placed in a land area already above more than 600 m over sea level. * device: provides a description of the starting characters of the mobile phone that is used to collect information. Considering the smartphone that has been used as part of the MDAS (Xiaomi mi 10 Lite), it should come as no surprise that it is identified as Xiaomi_M2002J9G, which is the code used for such smartphones in mobile communications. In addition to the pieces of data collected as shown in Figure 10, there were several other files with equivalent information extended in a more profuse manner in the GitHub project created for data storage. They are available in [37] (see in Supplementary Materials). * Combined UAV and MDAS landing. As previously determined, an experiment regarding how landing could be carried out with the whole measuring equipment mounted was performed. While the addition of hardware to the UAV presented some challenges in terms of how the latter would move (which included landing), in the end, we had the expectation that the drone would be usable with the MDAS. The obtained results corroborated this. It must be stressed that, as explained in the abstract and as outlined in [37], the flights that were carried out during the UAV tests proved that the drone moved around more than 40 cells from the Orange network operator LTE system, as there were more than 40 cell identifiers collected as flight data. In addition to that, it must be mentioned how it was possible to retrieve information not only from the mobile network signal, but also from the nature of the mission. For example, the speed, altitude or trajectory of the drone can be known from having a look at the information both contained in Figure 10 and the data available at [37]. The latter shows that drone flight was carried out around 40.43 latitude and \(-\)3.65 longitude degrees as coordinates at an altitude over sea level of around 700 m, while travelling throughout more than 40 nano LTE cells and signal power between \(-\)75 and \(-\)113 dB (as shown in Figure 10).