Section: 4.1 Overall Architecture
Content: An NG-RAN node is either: - a gNB, providing NR user plane and control plane protocol terminations towards the UE; or - an ng-eNB, providing E-UTRA user plane and control plane protocol terminations towards the UE. The gNBs and ng-eNBs are interconnected with each other by means of the Xn interface. The gNBs and ng-eNBs are also connected by means of the NG interfaces to the 5GC, more specifically to the AMF (Access and Mobility Management Function) by means of the NG-C interface and to the UPF (User Plane Function) by means of the NG-U interface (see TS 23.501[ System architecture for the 5G System (5GS) ]  [3]). NOTE: The architecture and the F1 interface for a functional split are defined in TS 38.401[ NG-RAN; Architecture description ]  [4]. The NG-RAN architecture is illustrated in Figure 4.1-1 below. Figure 4.1-1: Overall Architecture