4 General

38.4253GPPNG-RANNR user plane protocolRelease 17TS

4.1 General aspects

The NR user plane protocol is located in the User Plane of the Radio Network layer over either the Xn or the X2 or the F1 interface or the UP interface between eNB-CP and eNB-UP.

The NR user plane protocol is used to convey control information related to the user data flow management of data radio bearers.

Each NR user plane protocol instance is associated to one data radio bearer only. There is one NR user plane instance per GTP tunnel. When a GTP tunnel is set up, a new NR user plane instance is set up.

If configured, NR user plane protocol instances exist at the Master node and the Secondary node in the context of DC or at nodes hosting F1-U protocol terminations or at eNB-CP and eNB-UP. The NR user plane protocol supports direct communication between NR user plane protocol entities, regardless of whether they terminate the same or different user plane interfaces.

NOTE: User data radio bearers may be setup for data forwarding purposes during Xn HO or during DC related mobility without requiring the execution of any additional data radio bearer related user plane protocol functions related to an NR user plane protocol instance.

On each data radio bearer, the NR user plane protocol operates with RLC AM or RLC UM.

In this version of the present document, NR user plane protocol data is conveyed by GTP-U protocol means, more specifically, by means of the "NR RAN Container" GTP-U extension header as defined in TS 29.281 [2].