ying and adapting their networks. Another central idea in the design of 5G network was to minimize dependencies between the access network and the core net- work with a converged access-agnostic core network with a common interface which inte- grates different 3GPP and non-3GPP access types. 5G is a service-centric architecture which strives to deliver the entire network as a service. 3GPP system architecture group took the approach to rearchitect the LTE core network based on a service-oriented framework. This involves breaking everything down to more functional granularity. The MME no longer exists and its functionality has been redistribu- ted between mobility management and session management NFs. As such, registration, reachability, mobility management, and connection management are now considered new services offered by a new general NF labeled as AMF. Session establishment and session management, also formerly part of the MME, are now new services offered by a new NF called session management function (SMF). Furthermore, packet routing and forwarding functions, currently performed by the SGW and PGW in 4G, will now be realized as ser- vices rendered through a new NF called UPF. The main reason for this new architectural approach is to enable a flexible network as a service solution. By standardizing a modular- ized set of services, various deployment options such as centralized, distributed, or mixed configurations will be enabled for different users or applications. The dynamic service chaining lay the groundwork for network slicing which is an important concept in 5G to sat- isfy the diverse user and application demands, shifting the design emphasis on software rather than hardware. The physical boxes where these software services are instantiated could be in the cloud or on any targeted general-purpose hardware in the system. In the following sections, we will discuss the reference architecture, network entities, and interfaces of the 3GPP 5G access and the core networks. The user-plane and control-plan