8.9.5 Change of gNB-CU-UP

38.4013GPPArchitecture descriptionNG-RANRelease 17TS

Figure 8.9.5-1 shows the procedure used for the change of gNB-CU-UP within a gNB.

Figure 8.9.5-1: Change of gNB-CU-UP

1. Change of gNB-CU-UP is triggered in gNB-CU-CP based on e.g., measurement report from the UE.

2-3. Bearer Context Setup procedure is performed as described in clause 8.9.2.

4. F1 UE Context Modification procedure is performed to change the UL TNL address information for F1-U for one or more bearers in the gNB-DU.

5-6. Bearer Context Modification procedure (gNB-CU-CP initiated) is performed to enable the gNB-CU-CP to retrieve the PDCP UL/DL status and to exchange data forwarding information for the bearer.

7-8. Bearer Context Modification procedure is performed as described in clause 8.9.2.

9. Data Forwarding may be performed from the source gNB-CU-UP to the target gNB-CU-UP.

10-12. Path Switch procedure is performed to update the DL TNL address information for the NG-U towards the core network.

13-14. Bearer Context Release procedure (gNB-CU-CP initiated) is performed as described in clause 8.9.3.