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Content for  TS 38.401  Word version:  16.8.0

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8.13  Overall procedures for MDT |R16|Word‑p. 67

The following clauses describe the overall procedures for MDT measurement involving E1 and F1.

8.13.1  Signalling based MDT activationWord‑p. 67

The signalling flow for Signalling based MDT activation involving E1 and F1 is shown in Figure 8.13.1-1.
Reproduction of 3GPP TS 38.401, Fig. 8.13.1-1: Signalling based MDT Activation
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Step 1.
The AMF starts a trace session and sends a TRACE START message to the gNB. The AMF shall consider the MDT user consent information when activating an MDT trace session for the UE as defined in TS 32.422. TRACE START message includes the parameters for configuring MDT measurements.
Step 2.
The gNB-CU-CP decides if the gNB-CU-UP, or the gNB-DU, or both, should be involved in the MDT measurement. If the gNB-CU-UP should be involved in the MDT measurement, the gNB-CU-CP sends TRACE START message to the gNB-CU-UP, including MDT configuration parameters.
Step 3.
If the gNB-DU should be involved in the MDT measurement, the gNB-CU-CP sends TRACE START message to the gNB-DU, including MDT configuration parameters.
Each node involved in the MDT measurement reports the measurements collected directly to the TCE the node has been configured with.
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8.13.2  Management based MDT activationWord‑p. 67

8.13.2.1  GeneralWord‑p. 67

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.
Each node receiving an MDT activation indication reports the measurements collected according to such activation directly to the TCE the node has been configured with.
The signalling flow for management based MDT in gNB-CU-CP, gNB-DU and gNB-CU-UP is shown in Figure 8.13.2.2-1, Figure 8.13.2.3-1 and in Figure 8.13.2.4-1 respectively.
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8.13.2.2  Management based MDT Activation in gNB-CU-CPWord‑p. 68

The signalling flow for Management based MDT Activation in gNB-CU-CP is shown in Figure 8.13.2.2-1.
Reproduction of 3GPP TS 38.401, Fig. 8.13.2.2-1: Management based MDT Activation in gNB-CU-CP
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Step 1.
The EM sends a Trace Session activation request to the gNB-CU-CP. This request includes the parameters for configuring UE measurements.
Step 2.
The gNB-CU-CP shall select the suitable UEs for MDT data collection. If the UE is not in the specified area or if the serving PLMN is not within the Management Based MDT PLMN List the UE shall not be selected by the gNB-CU-CP for MDT data collection as defined in TS 32.422.
For each selected UE, if the gNB-CU-UP should perform MDT measurement, the gNB-CU-CP sends TRACE START message to the gNB-CU-UP, including MDT configuration parameters.
Step 3.
For each selected UE, if the gNB-DU should perform MDT measurement, the gNB-CU-CP sends TRACE START message to the gNB-DU, including MDT configuration parameters.
Step 4.
The gNB-CU-CP may send CELL TRAFFIC TRACE message to the AMF for the selected UE, including Trace ID for MDT. The AMF forwards Trace ID and UE identity to the TCE.
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8.13.2.3  Management based MDT Activation in gNB-DUWord‑p. 68

The signalling flow for Management based MDT Activation in gNB-DU is shown in Figure 8.13.2.3-1.
Reproduction of 3GPP TS 38.401, Fig. 8.13.2.3-1: Management based MDT Activation in gNB-DU
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Step 1.
The gNB-CU-CP sends UE CONTEXT SETUP REQUEST message to the gNB-DU, including Management based MDT PLMN List.
Step 2.
The gNB-DU sends UE CONTEXT SETUP RESPONSE message to the gNB-CU-CP.
Step 3.
The EM sends a Trace Session activation request to the gNB-DU. This request includes the parameters for configuring UE measurements.
Step 4.
The gNB-DU shall select the suitable UEs for MDT data collection. If the UE is not in the specified area or if the serving PLMN is not within the Management Based MDT PLMN List the UE shall not be selected by the gNB-DU for MDT data collection as defined in TS 32.422.
For each selected UE, the gNB-DU may send CELL TRAFFIC TRACE message to the gNB-CU-CP in the F1 UE associated signalling, including Trace ID for MDT.
Step 5.
Upon reception of a CELL TRAFFIC TRACE message from F1, the gNB-CU-CP shall send CELL TRAFFIC TRACE message to the AMF for this UE, including Trace ID for MDT. The AMF forwards Trace ID and UE identity to the TCE.
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8.13.2.4  Management based MDT Activation in gNB-CU-UPWord‑p. 69

The signalling flow for Management based MDT Activation in gNB-CU-UP is shown in Figure 8.13.2.4-1.
Reproduction of 3GPP TS 38.401, Fig. 8.13.2.4-1: Management based MDT Activation in gNB-CU-UP
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Step 1.
The gNB-CU-CP sends BEARER CONTEXT SETUP REQUEST message to the gNB-CU-UP, including Management based MDT PLMN List.
Step 2.
The gNB-CU-UP sends BEARER CONTEXT SETUP RESPONSE message to the gNB-CU-CP.
Step 3.
The EM sends a Trace Session activation request to the gNB-CU-UP. This request includes the parameters for configuring UE measurements.
Step 4.
The gNB-CU-UP shall select the suitable UEs for MDT data collection. If the serving PLMN is not within the Management Based MDT PLMN List the UE shall not be selected by the gNB-CU-UP for MDT data collection as defined in TS 32.422.
For each selected UE, the gNB-CU-UP may send CELL TRAFFIC TRACE message to the gNB-CU-CP in the E1 UE associated signalling, including Trace ID for MDT
Step 5.
Upon reception of a CELL TRAFFIC TRACE message from E1, the gNB-CU-CP shall send CELL TRAFFIC TRACE message to the AMF for this UE, including Trace ID for MDT. The AMF forwards Trace ID and UE identity to the TCE.
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8.13.2.5  User consent propagation in EN-DCWord‑p. 70

In the EN-DC case, the EM provides the MDT configuration to both MeNB and en-gNB independently.
As specified in TS32.422 [20] 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 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.
Reproduction of 3GPP TS 38.401, Fig. 8.13.2.5-1:	User consent propagation in EN-DC
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Step 0.
User Context information are made available at the MME.
Step 1.
The MME sends INITIAL CONTEXT SETUP REQUEST message to the MeNB, including Management Based MDT Allowed IE and the Management based MDT PLMN List IE to communicate user consent to the eNB.
Step 2.
The MeNB sends SGNB ADDITION REQUEST to the gNB-CU-CP at EN-DC setup. This request includes Management Based MDT Allowed IE and, optionally, the Management based MDT PLMN List IE, if available.
Step 3a.
The user consent is communicated to the gNB-DU at the UE context setup by including the Management based MDT PLMN List IE in the UE CONTEXT SETUP REQUEST.
Step 3b.
The user consent is communicated to the gNB-CU-UP at the bearer context setup by including the Management based MDT PLMN List IE in the BEARER CONTEXT SETUP REQUEST.
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8.14  Self-optimisation |R16|Word‑p. 71

8.14.1  Overall procedures for MROWord‑p. 71

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

8.14.1.1  Signalling of RLF information from gNB-CU to gNB-DUWord‑p. 71

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.
Reproduction of 3GPP TS 38.401, Fig. 8.14.1.1-1: Example of signalling of RLF information from gNB-CU to gNB-DU in NG RAN
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Step 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.
Step 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.
Step 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.
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