The present document provides an overview and overall description of the NG-RAN and focuses on the radio interface protocol architecture of NR connected to 5GC (E-UTRA connected to 5GC is covered in the 36 series).
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