# Unmanned Aerial Traffic Management System Architecture for U-Space In-Flight Services
## 4 UTM System Architecture
### Discussion  
In this section, we discuss the functionalities implemented by the U-space services of our UTM architecture, when compared to those expected in the current definition of the U-space ecosystem. For that, we have summarized in Table 4 the expected functionalities to be covered by each of the U-space services included in our system, according to the bibliography studied in Section 2.1. In the following, we discuss which capabilities are already covered by our system and the missing points for future implementations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**U-Space Service** & **Functionalities** & **Covered in Our** \\  & & **UTM System** \\ \hline \multirow{4}{*}{Tracking} & Cooperative UAS tracking & ✓ \\ \cline{2-3}  & Non-cooperative UAS tracking & ✗ \\ \cline{2-3}  & Capability to exchange data with other services & ✓ \\ \cline{2-3}  & Real-time tracking with data fusion from multiple sources & ✓ \\ \cline{2-3}  & Tracking data recording & ✓ \\ \hline \multirow{4}{*}{Monitoring} & Air situation monitoring & ✓ \\ \cline{2-3}  & Non-cooperative UAS identification & ✗ \\ \cline{2-3}  & Flight non-conformance detection & ✓ \\ \cline{2-3}  & Restricted area infringement detection & ✓ \\ \cline{2-3}  & Provision of traffic information for UAS operators & ✗ \\ \cline{2-3}  & Conflict alerts & ✓ \\ \hline \multirow{2}{*}{Emergency Management} & Emergency alerts & ✓ \\ \cline{2-3}  & Provision of assistance information for UAS operators & ✓ \\ \hline \multirow{4}{*}{Tactical Deconfliction} & Transmission of deconfliction information from the USM to the UAS \\ \cline{1-1} \cline{2-3}  & Transmission of deconfliction information in real time & ✓ \\ \cline{1-1} \cline{2-3}  & Transmission of deconfliction information in real time & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the functionalities to be covered by the U-space services included in our UTM system. Figure 10: (**Left**), a UAS with a flight plan crossing a geofence. The last waypoint of its flight plan before entering the geofence (WP\({}_{1}\)) and the first waypoint after leaving it (WP\({}_{2}\)) are obtained, and this portion of the flight plan is replaced by an alternative route (dashed line). (**Right**), a UAS that is inside a geofence. The escape point (WP\({}_{2}\)) is that on the geofence’s border closest to the UAS (WP\({}_{1}\)). From WP\({}_{3}\), which is already at a safety distance from the geofence, to the first point of the flight plan after leaving the geofence (WP\({}_{4}\)), an alternative route avoiding the geofence is inserted to modify the original flight plan. * _Tracking_. This service is supposed to consider cooperative and non-cooperative UAS, but our current implementation only manages cooperative UAS. This is because we have focused on enabling automated decision-making for the operating UAS, which makes no sense for non-cooperative vehicles. Those should be treated as uncontrollable intruders (i.e., threats) in the airspace. However, our Tracking module does have the capability to update and record data in real time from different sources. Other services can also access these data through the DB module if needed. * _Monitoring_. As in the previous case, our current implementation does not consider non-cooperative UAS. We did not establish a specific communication link to provide traffic information to the UAS operators either, though this could be easily done through the USM. However, our Monitoring module does accomplish all the other expected functionalities, i.e., it detects and alerts in real time about conflicts related to flight non-conformances, geofences, and inter-UAS separation. * _Emergency Management_. This service is expected to provide the UAS operators with notifications about alerts and any other emergency assistance. Besides, our EM module includes automated decision-making capabilities, in order to manage threats in real time by proposing safe and optimal actions to the UAS. * _Tactical Deconfliction_.