3GPP 38.300 v19.3.0 — the document's own text
4.3.2.2 Xn Control Plane
Taught in 4. What NR is — the shape of the 5G radio network (TSG RAN — the group that specifies the radio, in depth), 2. The six working groups and the line between them (TSG RAN — the group that specifies the radio, overview), 4. What NR actually is, in the shape its own document gives it (TSG RAN — the group that specifies the radio, overview), 2. The six groups, and what each one worries about (TSG RAN — the group that specifies the radio, quick start), 3. What NR is, read off the document itself (TSG RAN — the group that specifies the radio, quick start).
The Xn control plane interface (Xn-C) is defined between two NG-RAN nodes. The control plane protocol stack of the Xn interface is shown on Figure 4.3.2.2-1. The transport network layer is built on SCTP on top of IP. The application layer signalling protocol is referred to as XnAP (Xn Application Protocol). The SCTP layer provides the guaranteed delivery of application layer messages. In the transport IP layer point-to-point transmission is used to deliver the signalling PDUs.
The Xn-C interface supports the following functions:
- Xn interface management;
- UE mobility management, including context transfer and RAN paging;
- Dual connectivity.