Tech-invite3GPPspaceIETF RFCsSIP
Quick21222324252627282931323334353637384‑5x

Content for  TS 38.401  Word version:  17.1.1

Top   Top   Up   Prev   Next
1…   5…   6…   6.1.4   6.1.5…   6.2…   7…   8…   8.2…   8.2.2…   8.2.3…   8.2.4   8.2.5   8.3…   8.4…   8.4.4…   8.5…   8.9…   8.9.4…   8.9.6…   8.9.7…   8.10   8.11…   8.12…   8.13…   8.14…   8.15…   8.16…   8.17…   8.17.3…   8.17.4   8.18…   8.19…   8.19.2   8.19.3   8.19.4…   9…   A…

 

8.15  Overall procedures for NR MBS |R17|p. 87

8.15.1  Generalp. 87

The following clauses describe the overall procedures for NR MBS involving E1 and F1.

8.15.1.1  Broadcast MBS Session Setupp. 87

Figure 8.15.1.1-1 illustrates an examplified interaction of NGAP, E1AP, F1AP and RRC protocol functions at Broadcast MBS Session Setup.
Copy of original 3GPP image for 3GPP TS 38.401, Fig. 8.15.1.1-1: Broadcast MBS Session Setup
Figure 8.15.1.1-1: Broadcast MBS Session Setup
(⇒ copy of original 3GPP image)
Up
Step 1.
The 5GC starts the broadcast session by sending the NGAP Broadcast Session Setup Request message to the gNB containing the TMGI, S-NSSAI, 5G QoS Profile, area information and transport information (for NG-U multicast transport it provides the IP multicast address and the IP source specific multicast address, for NG-U unicast transport it provides an GTP UL TEID) and optionally an alternative set of transport information.
Step 2/3.
The gNB-CU-CP sets up the broadcast bearer context, providing NG-U transport information from the 5GC to the gNB-CU-UP and receiving from the gNB-CU-UP the NG-U GTP DL TEID in case NG-U unicast transport was selected and an F1-U GTP UL TEID per MRB.
Step 4.
In case of NG-U multicast transport, the gNB-CU-UP joins the NG-U multicast group.
Step 5/6.
The gNB-CU-CP establishes the Broadcast MBS Session Context at the DU, providing MRB configuration, other relevant session parameters and F1-U GTP UL TEID information, and receiving F1-U GTP DL TEID information.
Step 7/8.
The gNB-CU-CP triggers BC Bearer Context Modification Request towards the gNB-CU-UP to provide the F1-U GTP DL TEID information.
Step 9.
The DU configures broadcast resources and provides broadcast configuration information to the UEs by means of MCCH.
Step 10.
The gNB-CU CP successfully terminates the NGAP broadcast Session Setup procedure. In case the gNB has chosen NG-U unicast transport, NG-U GTP DL TEID information is provided to the 5GC.
Step 11.
The broadcast MBS media stream is provided to the UEs.
On NG-U, in case of location dependent broadcast MBS Sessions, multiple shared NG-U transport tunnels may need to be setup, one per Area Session ID served by the gNB.
In case of shared NG-U termination,
  • the gNB-CU-UP may provide the gNB-CU-CP at E1 setup or configuration update about established shared NG-U terminations, indicated by one or several MBS Session IDs.
  • at establishment of the BC bearer context in the gNB-CU-UP, the gNB-CU-CP may request the gNB-CU-UP to either apply the available MRB configuration of the shared NG-U termination, or to apply the MRB configuration requested by the gNB-CU-CP. The gNB-CU-UP provides the MRB configuration to the gNB-CU-CP if the MRB configuration requested by the gNB-CU-CP and the available MRB configuration of the shared NG-U termination are different.
Up

8.15.1.2  Multicast MBS Session Context Establishmentp. 88

Figure 8.15.1.2-1 illustrates an examplified interaction of NGAP, E1AP, F1AP and RRC protocol functions for Multicast MBS Session Context Establishment.
Copy of original 3GPP image for 3GPP TS 38.401, Fig. 8.15.1.2-1: Multicast MBS Session Context establishment
Up
Step 1.
A multicast session context is established by the 5GC.
Step 2/3.
If not yet existing, the gNB-CU-CP establishes the multicast bearer context at the gNB-CU-UP, in order to retrieve for unicast NG-U transport the GTP DL TEID, a shared resource address (GTP DL TEID).
Step 4/5.
If applicable, the gNB-CU-CP establishes the Multicast Context at the DU, providing MRB configuration. It may contain MBS Area Session ID information.
Step 6.
Dependent on e.g. joined UEs, the gNB-DU triggers the establishment of an F1-U tunnel, which is established either per DU or per cell or per MBS Area Session ID. The receiving gNB-CU-CP may need to fetch a gNB side NG-U TNL address information for the gNB-CU-UP by means of a E1AP MC Bearer Context Modification procedure.
Step 7/8.
The gNB-CU CP triggers the NGAP Distribution Setup procedure. For unicast transport, DL/UL GTP TEIDs are exchanged, for multicast transport, multicast address information is fetched from the 5GC.
Step 9/10.
The gNB-CU-UP side of the F1-U and NG-U UP entity is established by means of the E1AP MC Bearer Context Modification procedure, providing the DU side F1-U TNL address and the 5GC NG-U TNL address to the gNB-CU-UP, which provides the gNB-CU-UP side F1-U TNL address in return.
Step 11.
The gNB-CU-UP side F1-U TNL address is provided to the gNB-DU.
Step 12.
In case of NG-U multicast transport, the gNB-CU-UP joins the NG-U multicast group.
Step 13.
The gNB-CU-CP RRC-configures each UE which has joined the multicast group.
Step 14.
The gNB successfully terminates the NGAP procedure for establishing the multicast session context.
Step 15.
The multicast MBS media stream is provided to the UEs.
On NG-U, in case of location dependent multicast MBS Sessions, multiple shared NG-U transport tunnels may need to be setup, one per Area Session ID served by the gNB.
In case of shared NG-U termination,
  • the gNB-CU-UP may provide the gNB-CU-CP at E1 setup or configuration update about established shared NG-U terminations, indicated by one or several MBS Session IDs.
  • at establishment of the MC bearer context in the gNB-CU-UP, the gNB-CU- CP may request the gNB-CU-UP to either apply the available MRB configuration of the shared NG-U termination, or to apply the MRB configuration requested by the gNB-CU-CP. The gNB-CU-UP provides the MRB configuration to the gNB-CU-CP if the MRB configuration requested by the gNB-CU-CP and the available MRB configuration of the shared NG-U termination are different.
Up

Up   Top   ToC