Content for  TS 38.401  Word version:  18.4.0

In Management Based Trace Activation towards a gNB-CU-CP, gNB-CU-UP or a gNB-DU can be fulfilled with the Cell Traffic trace functionality defined in TS 32.422. The configuration parameters of the Trace Session that are received by a node in split RAN architecture are defined in TS 32.422. The following description is valid for both an en-gNB and a gNB. If the MDT measurement is initiated by the EM towards the gNB-CU-CP, and if the activation involves measurements collected by multiple nodes under the same gNB-CU-CP control in a split RAN architecture, the EM sends MDT measurement activation to the gNB-CU-CP and the gNB-CU-CP may further decide which gNB-DU(s) or which gNB-CU-UP(s) to perform the MDT measurement. When gNB-CU-CP or a gNB-DU receive the Trace Session Activation message from the management system for a given cell or a list of cell(s) under its control, the gNB-CU-CP or gNB-DU shall start a Trace Session for the given cell or list of cell(s). For Management Based MDT sent directly to a gNB-CU-UP, no MDT Area Configuration (apart from PLMN IDs) is to be included in the MDT activation indication. The signalling flows for management based MDT activation in gNB-CU-CP, gNB-DU and gNB-CU-UP are shown in Figure 8.13.2.2-1, Figure 8.13.2.3-1 and in Figure 8.13.2.4-1 respectively.

The signalling flow for Management based MDT Activation in gNB-CU-CP is shown in Figure 8.13.2.2-1.

If the UE reports an indication of measurement pollution, the gNB-CU-CP shall, if supported, include such indication as part of the measurement report to be sent to the TCE so that the TCE is able to correlate and filter the affected measurements.

The signalling flow for Management based MDT Activation in gNB-DU is shown in Figure 8.13.2.3-1.

The signalling flow for Management based MDT Activation in gNB-CU-UP is shown in Figure 8.13.2.4-1.

In the EN-DC case, the EM provides the MDT configuration to both MeNB and en-gNB independently. As specified in TS 32.422 in Management based MDT getting user consent is required before activating the MDT functionality because of privacy and legal obligations. In the case of EN-DC user consent gets communicated to the MeNB at the UE context setup procedure using the INITIAL CONTEXT SETUP REQUEST message. In particular when the Management Based MDT Allowed IE is contained in the INITIAL CONTEXT SETUP REQUEST message, the MeNB stores it in the UE context and uses it, together with information in the Management Based MDT PLMN List IE, if available, to allow subsequent selection of the UE for management based MDT as specified in TS 32.422. The MeNB may also receive user consent information in the HANDOVER REQUEST message. The MeNB will forward the MDT user consent to the SgNB at EN-DC setup. In particular, if available in the UE context, the MeNB will include the Management Based MDT Allowed IE and the Management Based MDT PLMN List IE in the SGNB ADDITION REQUEST message to the SgNB. Furthermore, the user consent will be forwarded to the relevant gNB-CU-UP at the bearer context setup or to the gNB-DU by including the Management Based MDT PLMN List IE in the BEARER CONTEXT SETUP REQUEST or UE CONTEXT SETUP REQUEST. The signalling flow for User consent proposation in EN-DC is shown in Figure 8.13.2.5-1.

As specified in TS 32.422 in Management based MDT getting user consent is required before activating the MDT functionality because of privacy and legal obligations. User consent is communicated to the MN at the UE context setup procedure using the INITIAL CONTEXT SETUP REQUEST message, or in HANDOVER REQUEST and PATH SWITCH REQUEST ACKNOWLEDGE messages. Modified user consent information may be received in the UE CONTEXT MODIFICATION REQUEST message. The MN stores the received information in the UE context and uses it to allow subsequent selection of the UE for management based MDT as specified in TS 32.422. The MN will forward the MDT user consent to the SN at MR-DC setup, i.e., if available in the UE context, the MN will include the Management Based MDT PLMN List IE in the S-NODE ADDITION REQUEST message or in the S-NODE MODIFICATION REQUEST message sent to the SN. Furthermore, in NR-DC and NGEN-DC, the user consent will be forwarded to the relevant SgNB-CU-UP at the bearer context setup or to the SgNB-DU by including the Management Based MDT PLMN List information in the BEARER CONTEXT SETUP REQUEST or UE CONTEXT SETUP REQUEST. Furthermore, in NR-DC and NGEN-DC, the user consent may be updated to the relevant SgNB-CU-UP at the bearer context modification or to the SgNB-DU by including the Management Based MDT PLMN List information in the BEARER CONTEXT MODIFICATION REQUEST or UE CONTEXT MODIFICATION REQUEST. The signalling flow for User consent propagation in NR-DC and NGEN-DC is shown in Figure 8.13.2.6-1.

In the MR-DC with 5GC case, the EM provides the MDT configuration to both MN and SN independently. In Management Based Trace Activation towards a SN, the SN may send the CELL TRAFFIC TRACE message including the Trace ID and privacy indicator to the MN as described in TS 32.422. Upon reception of the CELL TRAFFIC TRACE message from the SN, the MN will send a CELL TRAFFIC TRACE message including the Trace ID and privacy indicator to the CN for this UE. The CN forwards the Trace ID and other information to the TCE as specified in TS 32.422. The following shows a flow chart summarizing the functionality in MR-DC when the SN is the SgNB.