8.14 Self-optimisation

38.4013GPPArchitecture descriptionNG-RANRelease 17TS

8.14.1 Overall procedures for MRO

The following clauses describe the overall procedures for MRO involving F1.

8.14.1.1 Signalling of RLF information from gNB-CU to gNB-DU

The signalling flow for signalling of RLF information from gNB-CU to gNB-DU is shown in Figure 8.14.1.1-1, where the example where NG-RAN nodes exchange the RLF Report via the Xn: FAILURE INDICATION message has been considered.

Figure 8.14.1.1-1 Example of signalling of RLF information from gNB-CU to gNB-DU in NG RAN

1. A UE with a logged RLF Report connects to a cell in gNB2 and it signals the RLF Report to gNB2 by means of the RRC UE Information Request/Response procedures.

2. The gNB2 sends an Xn: Failure Indication to gNB1-CU where the UE may have previously been connected prior to the connection failure. This includes also the RLF Report.

3. The gNB1-CU sends the F1: Access and Mobility Indication message to the gNB1-DU, including the RLF Report.

It is also possible for the gNB-CU receiving the RLF Report from the UE to signal it directly to the gNB-DU by means of the F1: Access and Mobility Indication procedure.

8.14.1.2 Signalling of RACH information from gNB-CU to gNB-DU

The signalling flow for signalling of RACH information from gNB-CU to gNB-DU is shown in Figure 8.14.1.2-1, where the example where NG-RAN nodes exchange the RACH Report via the Xn: ACCESS AND MOBILITY INDICATION message has been considered.

Figure 8.14.1.2-1 Example of signalling of RACH information from gNB-CU to gNB-DU in NG-RAN

1. A UE with a RACH Report concerning cells of gNB1 connects to a cell in gNB2 and it signals the RACH Report to gNB2 by means of the RRC UE Information Request/Response procedures.

2. GNB2 sends an Xn: Access and Mobility Indication message to gNB1-CU where the UE may have previously been connected. This includes also the RACH Report.

3. GNB1-CU sends the F1: Access and Mobility Indication message to the gNB1-DU, including the RACH Report.

It is also possible for the gNB-CU receiving the RACH Report from the UE to signal it directly to the gNB-DU by means of the F1: Access and Mobility Indication procedure.