8.9.1 UE Initial Access

38.4013GPPArchitecture descriptionNG-RANRelease 17TS

The signalling flow for UE Initial access involving E1 and F1 is shown in Figure 8.9.1-1.

Figure 8.9.1-1: UE Initial Access procedure involving E1 and F1

Steps 1-8 are defined in clause 8.1.

9. The gNB-CU-CP sends the BEARER CONTEXT SETUP REQUEST message to establish the bearer　context in the gNB-CU-UP.

10 The gNB-CU-UP sends the BEARER CONTEXT SETUP RESPONSE message to the gNB-CU-CP, including F1-U UL TEID and transport layer address allocated by the gNB-CU-UP.

Steps 11-13 are defined in clause 8.1.

14. The gNB-CU-CP sends the BEARER CONTEXT MODIFICATION REQUEST message to the gNB-CU-UP, including F1-U DL TEID and transport layer address allocated by the gNB-DU.

15. The gNB-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the gNB-CU-CP.

Steps 16-22 are defined in clause 8.1.

NOTE: Steps 14-15 and steps 16-17 can happen in parallel, but both are before step 18.