8 Control and user plane stacks

23.2473GPPArchitectural enhancements for 5G multicast-broadcast servicesRelease 18TS

8.1 Control plane for Multicast and Broadcast services

8.1.1 General

The control plane protocol stacks for Multicast and Broadcast service between NG-RAN and MB-SMF is defined in the clause 8.1.1 and the other control plane protocol stacks for Multicast and Broadcast service are defined in the TS 23.501 [5] clause 8.2.

The control plane protocols for N4mb reference point between MB-SMF and MB-UPF are defined in TS 29.244 [17].

The reference point Nmb2 between MBSF and MBSTF will be defined in TS 26.502 [18] and TS 26.517 [22].

8.1.2 NG-RAN – MB-SMF

Legend:

– N2 SM information: This is the subset of NG-AP information that the AMF transparently relays between the NG-RAN and the MB-SMF, and is included in the NG-AP messages and the N11mb related messages, where the NG-RAN node has MBS capability and in this Release the NG-RAN is a 3GPP NR.

Figure 8.1.1-1: Control Plane between the NG-RAN and the MB-SMF

8.2 User plane for Multicast and Broadcast services

The User plane protocol stack for PDU session which handles the multicast operation is same with the PDU session user plane Protocol Stack defined in the TS 23.501 [5] clause 8.3.1.

The user plane protocol stack for MBS session in case of shared delivery is described in Figure 8.2-1 and Figure 8.2-2. In Figure 8.2-1, the UDP tunnel applies to N6mb and Nmb9, while in Figure 8.2-2, the plain IP multicast applies to N6mb. The user plane protocol stack for MBS session in case of individual delivery is described in Figure 8.2-3.

Figure 8.2-1: User Plane Protocol Stack for MBS session (UDP Tunnel)

Figure 8.2-2: User Plane Protocol Stack for MBS session (plain IP multicast)

– 5G-AN Protocol Layers: This set of protocols/layers depends on the AN:

– in this Release, the 5G-AN is a 3GPP NR, these protocols/layers are defined in TS 38.401 [16]. The radio protocol between the UE and the 5G-AN node (gNodeB) is specified in TS 38.300 [9].

Figure 8.2-3: User Plane Protocol Stack for MBS session in case of Individual delivery

– 5G-AN Protocol Layers: This set of protocols/layers depends on the AN:

– in this Release, the 5G-AN is a 3GPP NR, these protocols/layers are defined in TS 38.401 [16]. The radio protocol between the UE and the 5G-AN node (gNodeB) is specified in TS 38.300 [9].

NOTE: In Figure 8.2-3, the User Plane Protocol Stack between MB-UPF and AF/MBSTF is shown in Figure 8.2-1 and Figure 8.2-2.