## 3 Network Slicing Concepts  
The Katana Slice Manager is a network slicing mechanism developed in the scope of SGENESIS [6], that currently supports end-to-end slicing in 5G deployments across multiple layers of the infrastructure. The design and implementation of Katana is based on the 3 GPP Technical Report TR 28.801, Telecommunication management; Study on management and orchestration of network slicing for next generation network [7]. Following the concepts of the 3 GPP specification, the following definitions have been implemented:  
* Network Slice Instance (NSI): Includes all functionalities and resources required to accommodate end-to-end networking services. * Network Slice Template (NST): The description of the network slice to be created. * Components of an NSI: An NSI is a twofold twinning of the network components, both the physical and virtualized functions and the resources of the underlying ecosystem. These heterogeneous components can be defined and allocated to an NSI, but can also be shared among multiple NSIs. The Slice Manager manages the interconnection information, network graph, link requirements, etc. * Network Slice Subnet Instance (NSSI): An NSI may be composed of NSSIs. The NSSIs may represent different domains of the physical infrastructure, such as the NFVI, transport network, RAN, etc. An NSSI may include other NSSI (s). For example, a 5G Core network can constitute an NSSI. The Slice Manager is a centralized software component that manages all management and orchestration entities of the assigned infrastructure. In addition, it provides an interface for creating, modifying, monitoring, and deleting slices. Through the North Bound Interface (NBI), the Slice Manager interacts with either a coordination layer or directly with the network operator. It receives the Network Slice Template (NEST), which describes the particular slice details corresponding to the service requirements. The NEST includes details such as the list of NFV components (network services) that need to be instantiated, the WAN configuration, QoS, monitoring level, life-cycle stages, etc. The NEST follows the GSMA generic slice template [8]. The Slice Manager maps these details to specific actions for provisioning network slices. The Slice Manager also exposes an API interface for management and monitoring all \begin{table}
\begin{tabular}{c c c} \hline \hline
**Service Type** & **5G Slice Type** & **Characteristics** \\ \hline UAV Control & uRLLC & The UAV provided requires a reliable, low-latency channel for real-time control, especially in the case of BVLOS. \\ \hline Surveillance & eMBB & Video feed from drones will need to be delivered to the CC with high quality from drones or any other camera equipment available. \\ \hline Sensors & mMTC & Multiple number of small bit-rate flows conveying sensory data from the location and from the sensors equipped on team members. \\ \hline AR & eMBB & Video and audio services will be assigned to different eMBB slices to efficiently handle prioritization and isolation where needed. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mapping of 5G Slices to Emergency Services. slice instances. Through the South Bound Interface (SBI), it interfaces to the components of the Management and Orchestration Layer (MANO), namely the NFV Orchestrator (NFVO), the Element Management System (EMS) and the WAN Infrastructure Management (WIM), to control every device on the data plane. The sequence of a slice creation is depicted in detail in Figure 2.  
An example of the workflow for the creation of a network slice is the following:  
* A RESPOND-A operator requests, through the portal, the creation of a new slice using the Slice Manager's NBI, selecting a particular slice profile to deploy his  
Figure 2: Sequence diagram of slice creation. communication service (i.e., comprising of a number of NS plus, not mandatory, a 5G NC system). * The NEST is created and parsed by the Slice Manager.