ents that led the design of NG-RAN architecture and interfaces included logical separation of signaling and data transport networks and separation of access and core NFs from transport functions, regardless of their possible physical co-location. Other considerations included independence of addressing scheme used in NG-RAN and 5GC from those of transport functions and control of mobility for radio resource control (RRC) connection via NG-RAN. The functional division across the NG-RAN interfaces has limited options and the interfaces are based on a logical model of the entity controlled through the corresponding interface. As was the case with LTE, one physical network ele- ment can implement multiple logical nodes. 12 Chapter 1 1.1.2 Virtualization of Network Functions NFV is an alternative approach to design, deploy, and manage networking services as well as a complement to SDN for network management. While they both manage networks, they rely on different methods. SDN separates the control and forwarding planes to offer a cen- tralized view of the network, whereas NFV primarily focuses on optimizing the network services themselves. NFV transforms the way that network operators architect networks by evolving standard server-based virtualization technology to consolidate various network equipment types into industrial-grade high-volume servers, switches, 4 and storage, which could be located in data centers, network nodes, and in the end-user premises. The NFV involves implementation of NFs in software that can run on a range of network server hardware that can be moved to or instantiated in various locations in the network as required, without the need for installa- tion of new equipment. The NFV is complementary to SDN, but not dependent on it or vice versa. It can be implemented without an SDN being required, although the two concepts/ solutions can be combined to gain potentially greater value. NFV goals can be achieved using non-SDN mechanisms, relying on the techniques currently in use in many data cen- te