## 5 Potential Use Cases
### Emergency Communication Critical System  
This use case aims at demonstrating the robustness or \"criticality\" of an emergency communication system under different conditions and potential mission stages. Currently, first-responders face very distinct and unpredicted network conditions that may drastically vary over time. The 3 GPP has done a great effort on standardizing the mission critical push-to-talk (MCPTT) service. This effort aims for 5G broadband networks to provide push-to-talk voice communications that get closer to the performance of private mobile radio or land mobile radio (PMR/LMR) voice, while at the same time they improve deployment time, interoperability, flexibility, and innovation. The final objective is to offer a cost-effective, open, interoperable alternative to legacy mission critical (MC) networks, while paving the way to the upcoming data and video services with broadband requirements. This use case can demonstrate the 5G NPN concept, allowing the owner to control its 5G network to serve a limited geographic area with optimized services using dedicated equipment. The key idea behind this use case is to have a responsive service that is able to cope with drastic network conditions, so that the first-responders are able to keep communicating regardless of the outage, communication demand increase, detection of poor communication quality and so forth. The coexistence of ordinary communications by other  
Figure 6: Matching the O-RAN architecture with the ML workflow ([43]). potential network consumers in the area should be taken into consideration, requiring to differentiate between the needs that each group has in terms of QoS and priority among other features. Based on the above, the first deployment scenario (Figure 7) of this use case describes a private 5G network providing services to various tenants or authorities in a concrete coverage area. The second one (Figure 8) intends to respond to an emergency situation in which national external authorities would access the concrete coverage area either by their own commercial network (in the case private and public coverages would overlap) or by attaching to the network already existent in the area. In this case the coexistence of a public 5G network to cover the needs of regular consumers and national authorities in the same coverage area where the private 5G network is deployed, will be considered in order to differentiate between the needs that each user, tenant or authority has in terms of QoS and priority among other features. In order to cope with the diverse requirements of first-responders, the use cases aim to deliver the emergency communication critical system as a private \"pop up network\", providing security and privacy, control and flexibility, leveraged by network slicing, vast bandwidth, light costs, and low latency. Depending on the executed use case, the required network service functions and application components will be instantiated in the main and edge NFVIs. When network and application services are being onboarded, the slicing will take place so the required resources allocation across the network can occur. For this use case, a network slice per  
Figure 8: Second deployment scenario of the emergency communication critical system. Figure 7: First deployment scenario of the emergency communication critical system. tenant or authority using mission critical services will be necessary. In that way, resource availability and mission critical services' 5G QoS mapping will be guaranteed. Although the scope of this use case is not to put into competition diverse mission critical instances, but to monitor the performance of the application itself and to trigger application self-healing mechanisms depending on the network conditions, several slices could be created, across both main and edge NFVI, in order to observe the priority behaviour of flows within the slice.