## 3 System Description  
If the current state-of-the-art is taken into consideration, the improvements offered by the system put forward in the paper become clearer, especially when considering the contributions that have been put forward in Section 1:  
1. Our built solution deals with an application domain that, judging from the reviewed literature, has not been given any relevant research so far. Therefore, we are providing research with a built prototype in an area of knowledge that has been almost previously untested, except for research studies that fall within this area but are focused on other objectives. 2. Use of an actual UAV enabled with Galileo as the Global Navigation Satellite System (GNSS). Rather than using an already existing UAV solution that has been built with purposes different from the ones put forward in this paper, a custom-made UAV has been developed for accurate sensing of mobile network signals. This customization has been used for two different purposes. On the one hand, a controller board (Navio2 [22]) has been used as a GNSS receptor for UAV positioning. Compared to other systems (GPS, GLONASS, Beidou, etc. ), and as it will be described, Galileo offers a higher degree of accuracy and a more robust signal that offers a more exact positioning for any device making use of it. This comes in as extremely useful for this application domain, as high accuracy is required to perform mobile network measurements that are likely to change in terms of output in a relatively small location. 3. End-user-friendly capabilities have been provided as well. One of the three subsystems of the prototype is devoted to the development of a Graphical User Interface that will be able to display, in an accurate manner, what kind of data are being collected, where they were taken from and the meaning of them. This tool makes it easier to infer knowledge from the data acquired in any location the UAV flies. These improvements have been summarized in Table 2. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Open Issue** & **Proposed Solution** & **Means Used for the Solution** \\ \hline No application & Research using UAVs to collect & Tailored UAV \\ domain research & information from mobile networks & Galileo as GNSS \\ \multirow{2}{*}{\begin{tabular}{c} Lack of \\ prototype deployment \\ \end{tabular} } & Using an actual UAV whenever it is & Tailored UAV \\  & suitable for development and & Galileo GNSS \\ \multirow{2}{*}{\begin{tabular}{c} Lack of UAV tailoring for the \\ application domain \\ \end{tabular} } & Using an actual UAV adapted to the & Tailored UAV \\  & & Galileo GNSS \\ \multirow{2}{*}{\
\begin{tabular}{c} Poor data \\ visualization resources \\ \end{tabular} } & Development of a GUI where significant & End user capabilities (GUI) \\ \multirow{2}{*}{
\begin{tabular}{c} End user \\ \end{tabular} } & Integration can be collected & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Solutions to the open issues provided by the proposed system. As previously mentioned in the introduction, and to properly answer the hypothesis that has been put forward, a system was designed with the idea of developing a tool that, from a hardware and software perspective, is capable of measuring useful parameters of a network used for wireless communications in a mobile environment. Our proposal can be described as a Cyber-Physical System (CPS), combining three different subsystems interacting with each other. For each of the subsystems, a collection of functional and non-functional requirements were defined with the purpose of guaranteeing a certain level of quality and synergy among all of the parts that comprise the system. These parts can be defined in the following manner:  
1. Open-source Unmanned Aerial Vehicle: this is the UAV that the authors of this paper have used to install the device used for measurements and to move it in a three-dimensional space. 2. Mobile Data Acquisition System (MDAS): this is used to collect data regarding the signal power levels in the areas where it is transported.