## 3 5G and Beyond
### Management and Deployment of 5G and Beyond Technology  
SDN and network function virtualization (NFV), as complementary technologies for 5G, make the management and deployment of 5G services cost efficient, faster and easier. These are actually the building blocks for more complex services, such as Cloud-RAN, network slicing and intelligence at edge. These services are discussed in this section. Slicing Architecture through SDN and NFV  
5G is expected to support a more flexible and dynamic network using network slicing, which is still a matter of active discussion among the main worldwide standardization organizations and also between telecom operators and vendors. 5G is inherently based on software-defined paradigms and NFV. Network slicing plays a key role in 5G because the network has to be adapted in real time to at least three different types of usage: machine-to-machine communications, critical communications, mobile broadband, and reliable low latency communications. As such, different types of slices were defined by GSMA [30], such as mobile broadband slice, massive IoT slices, and mission critical IoT slices. The different 5 GPP projects propose various slicing architectures but remain the same in the essential: a three-layered abstracted model. Indeed, the survey by [PERSON] et al. in [31] identified a common generic framework for 5G. As it can be seen in Figure 3, a 5G slicing architecture is based on three planes that gather different levels of abstraction: (i) at the top, the service layer, (ii) in the middle, the network function layer, and (iii) at the bottom, the infrastructure layer. The management and orchestration block (MANO) remains transverse to the aforementioned layers. The network function layer embeds all operations considering the life-cycle of the network functions based on the key performance indicators (KPIs) of the corresponding network service. The service layer is directly linked to the business cases and models but is also related to the operational constraints to orchestrate the slice. Each slice is set to comply with a given set of radio access technology (RAT) parameters suitable for that business case. We can imagine that a mobile network operator (MANO) offers a service to a given third party (e.g., a car manufacturer) through a specific end-to-end slice so that it can manage through a dedicated application programming interface (API). The MANO block is composed of the NFV orchestrator (NFVO), the virtual function network manager (VNFM), and the virtual infrastructure manager (VIM). Orchestration is made at three different levels: at the virtual function network (VNF) level through the VNFM, at the network service level through the NFVO, and at the virtual-machine level by the VIM, as defined by the architectural framework by [32]. NFV is inherently hierarchical, with MANO being the transverse brick, able to coordinate the entire orchestration process. The concept of orchestration also comes around when discussing service-oriented architectures, and the management of resources in network infrastructures [33]. This generic architecture gives an idea on how much SDN and NFV are related to 5G. Nevertheless, [PERSON] et al. in [34] went deeper into the 5G architecture implementation  
Figure 3: Generic framework across 5G architecture proposals. with SDN and NFV principles. They joined together the SDN ONF [35] client-server vision with the NFV architectural framework. On one hand, SDN allows to use control plane capabilities to enable slicing, but on the other hand, NFV architectural framework complements SDN by adding the life-cycle capabilities of virtualized network functions. Indeed, they stated that SDN principles are key to implementing 5G slicing due to the recursion property. Abstraction and recursion defined in SDN allow to coordinate successively hierarchical controllers, extending client-server relationships at several levels that are extended with the NFV architectural framework with SDN controllers with tenant and infrastructure roles.