# UAV Support for Mission Critical Services
## 4 Potential Roles of UAV in MCS
### Scenario 2  
This scenario concerns the handling of disasters, power grid failures, etc. In the mentioned cases, the infrastructure-based solutions are no longer working properly, and there is no UAV-GCS communication provided by the infrastructure. Therefore, the UAV flights must be autonomous or supported by a dedicated, proprietary connectivity solution. In this scenario, the MCS systems should:  
* Provide connectivity between the nodes and terminals of MCS. If possible, eventual integration with NTN (LEO satellites, etc.) should be provided for that purpose.
* Provide MCS services to support rescue teams. This is so far the role of solutions, such as TETRA (narrowband) and recently-designed LTE-MC (broadband). In such a solution, the MCS provides voice, short message and data transmission to a small group of users of a dedicated network. In LTE-MC, multimedia communication is allowed due to high bandwidth and the use of a flexible platform (IP Multimedia Subsystem (IMS)).
* Provide basic communication services to persons in the impacted area. It assumes the use of battery-powered commercial terminals (i.e., smartphones).
* Provide backup software platforms to solutions that should be working despite the lack of support from infrastructure-based service platforms--for example, processing data from IoT sensors, control of utilities, road traffic, Smart City solutions, Supervisory Control Furthermore, Data Acquisition (SCADA) systems, etc. Adding an ad hoc service platform is not supported by TETRA nor LTE-MC.  
The first requirement means that a proprietary radio technology has to be used between the UAV and the GCS, and the autonomy of flights is much more critical than in Scenario 1. This is not a substantial limitation, as many UAVs currently available come with a proprietary radio control solution. The second functionality of Scenario 2 is already described in Scenario 1, and in Scenario 2, it behaves similarly. The only difference is the (potential) lack of communication infrastructure-based networks provide.  
The third and fourth functionalities require a more sophisticated approach. It lies in substituting 'core' functions of a network that may have wired or wireless terminals (LTE Machine Type Communication (LTE-M), Narrowband Internet of Things (NB-IoT), Long Range Wide Area Network (LoraWAN), LTE, WiFi, etc.). In the case of wired solutions, the robotic and delivery UAVs may be used to make some temporary repair of the infrastructure if direct human or other robot access is impossible. For example, in such a case, a bespoke UAV can be used for fast fibre deployment in an 'over-the-ground' manner. However, this paper will focus on a wireless solution because UAVs may play a much more critical role in such a case. To that end, UAVs can be used to create temporary wireless solutions for the wireless technology needed.  
For this purpose, we need portable base stations with computing capabilities and mechanisms that provide interconnection of the wireless terminals of the solution to a platform (typically, such solutions use a client-server approach, and this also concerns Voice over IP (VoIP) or multimedia systems). A similar approach has already been used in Scenario 1. Still, in the mentioned case, there can be a need for more radio interfaces to be supported and also the addition of a platform that can interact with the appropriate terminals.  
Both scenarios come with two kinds of problems. The first one deals with the necessity of developing a procedure for MCS deployment in a specific area. Thus far, no such procedures have been defined. The second problem is linked to the ad hoc deployment of MCS service platform.