Content for  TS 38.423  Word version:  18.2.0

The M-NG-RAN node initiated S-NG-RAN node Release procedure is triggered by the M-NG-RAN node to initiate the release of the resources for a specific UE. The procedure uses UE-associated signalling.

The M-NG-RAN node initiates the procedure by sending the S-NODE RELEASE REQUEST message. Upon reception of the S-NODE RELEASE REQUEST message the S-NG-RAN node shall stop providing user data to the UE. The S-NG-RAN node UE XnAP ID IE shall be included if it has been obtained from the S-NG-RAN node. The M-NG-RAN node shall provide appropriate information within the Cause IE. The M-NG-RAN node may also provide appropriate information per PDU session resource within the Cause IE of the PDU Session Resources To Be Released List IE. Upon reception of the S-NODE RELEASE REQUEST message containing UE Context Kept Indicator IE set to "True", the S-NG-RAN node shall, if supported, only initiate the release of the resources related to the UE-associated signalling connection between the M-NG-RAN node and the S-NG-RAN node. If the S-NG-RAN node confirms the request to release S-NG-RAN node resources, it shall send the S-NODE RELEASE REQUEST ACKNOWLEDGE message to the M-NG-RAN node. If the S-NODE RELEASE REQUEST message contains a PDU session resource to be released which is configured with the SCG bearer option within the PDU Session Resources To Be Released List IE, the S-NG-RAN node shall include the RLC Mode IE within the DRBs To Be Released List IE in the S-NODE RELEASE REQUEST ACKNOWLEDGE message. The RLC Mode IE indicates the RLC mode used in the S-NG-RAN node for the DRB. If the S-NODE RELEASE REQUEST ACKNOWLEDGE message includes the SCG UE History Information IE, the M-NG-RAN node shall, if supported, use the information to update UE History Information with PSCell history. If the S-NODE RELEASE REQUEST ACKNOWLEDGE message includes the SN Mobility Information IE, the M-NG-RAN node shall, if supported, store this information and use it as defined in TS 37.340. Interaction with the Xn-U Address Indication procedure If the S-NG-RAN node provides data forwarding related information in the S-NODE RELEASE REQUEST ACKNOWLEDGE message for QoS flows mapped to DRBs configured with an SN terminated bearer option in the PDU Sessions To Be Released List - SN terminated IE, the M-NG-RAN node may decide to provide data forwarding addresses to the S-NG-RAN node and trigger the Xn-U Address Indication procedure as specified in TS 37.340. If the S-NODE RELEASE REQUEST message concerns a UE for which a Conditional PSCell Change has been triggered, the S-NG-RAN node shall, if supported, consider that the triggered Conditional PSCell Change has been executed, and M-NG-RAN node triggers the Xn-U Address Indication procedure as specified in TS 37.340. Interaction with the SN Status Transfer procedure If the UE Context Kept Indicator IE set to "True" and the DRBs transferred to MN IE are included in the S-NODE RELEASE REQUEST message, the S-NG-RAN node shall, if supported, provide the uplink/downlink PDCP SN and HFN status for the listed DRBs, as specified in TS 37.340.

If the S-NG-RAN node cannot confirm the request to release S-NG-RAN node resources, it shall send the S-NODE RELEASE REJECT message to the M-NG-RAN node with an appropriate cause indicated in the Cause IE.

If the S-NODE RELEASE REQUEST message refer to a context that does not exist, the S-NG-RAN node shall ignore the message. When the M-NG-RAN node has initiated the procedure and did not include the S-NG-RAN node UE XnAP ID IE the M-NG-RAN node shall regard the resources for the UE at the S-NG-RAN node as being fully released. Interactions with the UE Context Release procedure: If the M-NG-RAN node does not receive the reply from the S-NG-RAN node before it has to release the EN-DC connection, or it receives S-NODE RELEASE REQUEST REJECT, it may trigger the UE Context Release procedure. If the S-NG-RAN node received the UE CONTEXT RELEASE right after receiving the S-NODE RELEASE REQUEST (and before or after responding to it), the S-NG-RAN node shall consider the related M-NG-RAN node initiated S-NG-RAN node Release procedure as being the resolution of abnormal conditions and release the related UE context immediately.

This procedure is triggered by the S-NG-RAN node to initiate the release of the resources for a specific UE. The procedure uses UE-associated signalling.

The S-NG-RAN node initiates the procedure by sending the S-NODE RELEASE REQUIRED message to the M-NG-RAN node. Upon reception of the S-NODE RELEASE REQUIRED message, the M-NG-RAN node replies with the S-NODE RELEASE CONFIRM message. For each SN-terminated PDU session resource, the M-NG-RAN node may include the DL Forwarding UP Address IE and the UL Forwarding UP Address IE within the PDU Session Resources To Be Released Item IE to indicate that it requests data forwarding of uplink and downlink packets to be performed for that bearer. The S-NG-RAN node may start data forwarding and stop providing user data to the UE upon reception of the S-NODE RELEASE CONFIRM message, If the S-NODE RELEASE REQUIRED message contains an PDU session resource to be released which is configured with the SCG bearer option within the PDU sessions to be released List - SN terminated IE, the S-NG-RAN node shall include the RLC Mode IE within the DRBs To Be Released List IE in the PDU Session to be released List - SN terminated IE in the S-NODE RELEASE REQUIRED message. The RLC Mode IE indicates the RLC mode used in the S-NG-RAN node for the DRB. If the S-NODE RELEASE CONFIRM message includes the DRB IDs taken into use IE, the S-NG-RAN node shall, if applicable, act as specified in TS 37.340. If the S-NG-RAN node to M-NG-RAN node Container IE is included in the S-NODE RELEASE REQUIRED message, the M-NG-RAN node may use the contained information to apply delta configuration. If the S-NODE RELEASE REQUIRED message includes the SCG UE History Information IE, the M-NG-RAN node shall, if supported, use the information to update UE History Information with PSCell history. If the S-NODE RELEASE REQUIRED message contains the User Plane Error Indicator IE within the PDU Sessions List To be Released - UPError IE set to "GTP-U Error Indication Received", the M-NG-RAN node shall, if supported, consider that the PDU session is released due to GTP-U Error Indication received over the NG-U tunnel, and inform the SMF as specified in TS 23.527.

Not applicable.

Void.

This procedure is initiated by the S-NG-RAN node to request the M-NG-RAN node to execute a counter check procedure to verify the value of the PDCP COUNTs associated with SCG bearers established in the S-NG-RAN node. The procedure uses UE-associated signalling.

The S-NG-RAN node initiates the procedure by sending the S-NODE COUNTER CHECK REQUEST message to the M-NG-RAN node. Upon reception of the S-NODE COUNTER CHECK REQUEST message, the M-NG-RAN node may perform the RRC counter check procedure as specified in TS 33.401 and TS 33.501.

Not applicable.

Void.

The purpose of the RRC Transfer procedure is to deliver a PDCP-C PDU encapsulating an LTE RRC message or NR RRC message to the S-NG-RAN-NODE that it may then be forwarded to the UE, or from the S-NG-RAN-NODE, if it was received from the UE. The delivery status may also be provided from the S-NG-RAN-NODE to the M-NG-RAN-NODE using the RRC Transfer. The procedure is also used to enable transfer one of the following messages from the M-NG-RAN-NODE to the S-NG-RAN-NODE, when received from the UE:

• the NR RRC message container with the NR measurements;
• the E-UTRA RRC message container with the E-UTRA measurements;
• the NR RRC message container with the NR failure information;
• the NR RRC message container with the RRCReconfigurationComplete message;
• the NR RRC message container with the UE assistance information;
• the NR RRC message container with the IAB other information.

In case of RACH based SDT without UE context relocation, this procedure is also used to deliver a PDCP-C PDU encapsulating an NR RRC message between the new NG-RAN node and the old NG-RAN node. The procedure uses UE-associated signalling.

Dual Connectivity The M-NG-RAN-NODE initiates the procedure by sending the RRC TRANSFER message to the S-NG-RAN-NODE or the S-NG-RAN-NODE initiates the procedure by sending the RRC TRANSFER message to the M-NG-RAN-NODE. If the S-NG-RAN-NODE receives an RRC TRANSFER message which does not include the RRC Container IE in the Split SRB IE, or the RRC Container IE in the UE Report IE, or the RRC Container IE in the Fast MCG Recovery via SRB3 from MN to SN IE, or the RRC Container IE in the Fast MCG Recovery via SRB3 from SN to MN IE, it shall ignore the message. If the S-NG-RAN-NODE receives an RRC TRANSFER message with the Delivery Status IE in the Split SRB IE, it shall ignore the message. If the S-NG-RAN-NODE receives the RRC Container IE in the Split SRB IE, it shall deliver the contained PDCP-C PDU encapsulating an RRC message to the UE. If the S-NG-RAN-NODE receives the RRC Container IE in the Fast MCG Recovery via SRB3 from MN to SN IE, the S-NG-RAN-NODE shall deliver the contained RRC container encapsulating an RRC message to the UE. If the M-NG-RAN-NODE receives the Delivery Status IE in the Split SRB IE, the M-NG-RAN-NODE shall consider RRC messages up to the indicated NR PDCP SN as having been successfully delivered to UE by S-NG-RAN-NODE. If the M-NG-RAN-NODE receives the RRC Container IE in the Fast MCG Recovery via SRB3 from SN to MN IE, the M-NG-RAN-NODE shall consider MCG link failure detected at the UE as specified in TS 37.340. SDT The new NG-RAN-NODE initiates the procedure by sending the RRC TRANSFER message to the old NG-RAN-NODE or the old NG-RAN-NODE initiates the procedure by sending the RRC TRANSFER message to the new NG-RAN-NODE. If the new NG-RAN node receives the RRC Container IE in the SDT SRB between New NG-RAN node and Old NG-RAN node IE, it shall deliver the contained PDCP-C PDU encapsulating an RRC message to the UE. If the old NG-RAN-NODE receives the RRC Container IE in the SDT SRB between New NG-RAN node and Old NG-RAN node IE, it shall consider the contained PDCP-C PDU encapsulating an RRC message from the UE.

Not applicable.

In case of the split SRBs, the receiving node may ignore the message, if the M-NG-RAN-NODE has not indicated possibility of RRC transfer at the bearer setup.

The purpose of the Notification Control indication procedure is to provide information that for already established GBR QoS flow(s) for which notification control has been requested, the NG-RAN node involved in Dual Connectivity cannot fulfil the GFBR anymore or that it can fulfil the GFBR again. The procedure uses UE-associated signalling.

The M-NG-RAN node initiates the procedure by sending the NOTIFICATION CONTROL INDICATION message to the S-NG-RAN node. This procedure is triggered to notify the S-NG-RAN node for SN-terminated bearers, that resources requested from the M-NG-RAN node can either not fulfil the GFBR anymore or that the GFBR can be fulfilled again, as specified in TS 37.340. For a QoS flow indicated as not fulfilled anymore the M-NG-RAN node may also indicate an alternative QoS parameter set which it can currently fulfil in the Current QoS Parameters Set Index IE.

The S-NG-RAN node initiates the procedure by sending the NOTIFICATION CONTROL INDICATION message to the M-NG-RAN node. This procedure is triggered to notify the M-NG-RAN node that for MN-terminated bearers resources requested from the S-NG-RAN node can either not fulfil the GFBR anymore or that the GFBR can be fulfilled again, as specified in TS 37.340. For a QoS flow indicated as not fulfilled anymore the S-NG-RAN node may also indicate an alternative QoS parameters set which it can currently fulfil in the Current QoS Parameters Set Index IE. This procedure is triggered to notify the M-NG-RAN node that resources requested for SN-terminated bearers can either not fulfil the GFBR anymore or that the GFBR can be fulfilled again, as specified in TS 37.340. For a QoS flow indicated as not fulfilled anymore the S-NG-RAN node may also indicate an alternative QoS parameters set which it can currently fulfil in the Current QoS Parameters Set Index IE.

Void.

The purpose of the Activity Notification procedure is to allow an NG-RAN node to send notification to another NG-RAN node concerning:

• user data traffic activity for the UE, or
• user data traffic activity of already established QoS flows or PDU sessions, or
• RAN Paging failure.

The procedure uses UE-associated signalling.

NG-RAN node1 initiates the procedure by sending the ACTIVITY NOTIFICATION message to NG-RAN node2. The ACTIVITY NOTIFICATION message may contain one or more of the below:

• notification for UE context level user plane activity in the UE Context level user plane activity report IE.
• notification of user plane activity for the already established PDU sessions within the PDU Session Resource Activity Notify List IE.
• notification of user plane activity for the already established QoS flows within the PDU Session Resource Activity Notify List IE.
• notification of RAN Paging failure.

If the ACTIVITY NOTIFICATION message contains the RAN Paging Failure IE set to "true", NG-RAN node2 shall consider that RAN Paging has failed in NG-RAN node1 for the UE. NG-RAN node2 may discard the user plane data for that UE and consider that the UE context is unchanged.

If the User Plane traffic activity report IE for a reporting object is reported by NG-RAN node1 as "re-activated" and the reporting object was not reported as "inactive", the report for the concerned reporting object shall be ignored by NG-RAN node2.

The purpose of the E-UTRA - NR Cell Resource Coordination procedure is to enable coordination of radio resource allocation between an ng-eNB and a gNB that are sharing spectrum and whose coverage areas are fully or partially overlapping. During the procedure, the ng-eNB and gNB shall exchange their intended resource allocations for data traffic, and, if possible, converge to a shared resource. The procedure is only to be used for the purpose of E-UTRA - NR spectrum sharing. The procedure uses non-UE-associated signalling.

If case of network sharing with multiple cell ID broadcast with shared Xn-C signalling transport, as specified in TS 38.300, the E-UTRA - NR CELL RESOURCE COORDINATION REQUEST message and the E-UTRA - NR CELL RESOURCE COORDINATION RESPONSE message shall include the Interface Instance Indication IE to identify the corresponding interface instance. ng-eNB initiated E-UTRA - NR Cell Resource Coordination: An ng-eNB initiates the procedure by sending the E-UTRA - NR CELL RESOURCE COORDINATION REQUEST message to an gNB over the Xn interface. The gNB extracts the Data Traffic Resource Indication IE and it replies by sending the E-UTRA - NR CELL RESOURCE COORDINATION RESPONSE message. The gNB shall calculate the full ng-eNB resource allocation by combining the Data Traffic Resource Indication IE and the Protected E-UTRA Resource Indication IE that were most recently received from the ng-eNB. In case of conflict between the most recently received Data Traffic Resource Indication IE and the most recently received Protected E-UTRA Resource Indication IE, the gNB shall give priority to the Protected E-UTRA Resource Indication IE. gNB initiated E-UTRA - NR Cell Resource Coordination: An gNB initiates the procedure by sending the E-UTRA - NR CELL RESOURCE COORDINATION REQUEST message to an ng-eNB. The ng-eNB replies with the E-UTRA - NR CELL RESOURCE COORDINATION RESPONSE message. In case of conflict between the most recently received Data Traffic Resource Indication IE and the most recently received Protected E-UTRA Resource Indication IE, the gNB shall give priority to the Protected E-UTRA Resource Indication IE.

This procedure is initiated by the S-NG-RAN node to provide information on the used resources of the secondary RAT (e.g. NR resources during MR-DC operation) as specified in TS 23.501. The procedure uses UE-associated signalling.

The S-NG-RAN node initiates the procedure by sending the SECONDARY RAT DATA USAGE REPORT message to the M-NG-RAN node.

Not applicable.

Not applicable.

The purpose of the Trace Start procedure is to allow the M-NG-RAN node to request the S-NG-RAN node to initiate a trace session for a UE. The procedure uses UE-associated signalling.

The Trace Start procedure is initiated by the M-NG-RAN sending the TRACE START message to the S-NG-RAN for that specific UE. Upon reception of the TRACE START message, the S-NG-RAN node shall initiate the requested trace session as described in TS 32.422. If the Trace Activation IE includes

• the MDT Activation IE set to "Immediate MDT and Trace", and if the S-NG-RAN node is a gNB, it shall, if supported, initiate the requested trace session and MDT session as described in TS 32.422.
• the MDT Activation IE set to "Immediate MDT Only" or "Logged MDT only", and if the S-NG-RAN node is a gNB, it shall, if supported, initiate the requested MDT session as described in TS 32.422 and the S-NG-RAN node shall ignore the Interfaces To Trace IE and the Trace Depth IE.
• the MDT Location Information IE, within the MDT Configuration IE, and if the S-NG-RAN node is a gNB, it shall, if supported, store this information and take it into account in the requested MDT session.
• the MDT Activation IE set to "Immediate MDT Only" or "Logged MDT only", and if the Signalling based MDT PLMN List IE is included in the MDT Configuration IE, and if the S-NG-RAN node is gNB, it may use it to propagate the MDT Configuration as described in TS 37.320.
• the Bluetooth Measurement Configuration IE, within the MDT Configuration IE, and if the S-NG-RAN node is a gNB, it shall, if supported, take it into account for MDT Configuration as described in TS 37.320.
• the WLAN Measurement Configuration IE, within the MDT Configuration IE, and if the S-NG-RAN node is a gNB, it shall, if supported, take it into account for MDT Configuration as described in TS 37.320.
• the Sensor Measurement Configuration IE, within the MDT Configuration IE, the S-NG-RAN node shall take it into account for MDT Configuration as described in TS 37.320.
• the MDT Configuration IE, and if the S-NG-RAN Node is a gNB at least the MDT Configuration-NR IE shall be present, while if the S-NG-RAN Node is an ng-eNB at least the MDT Configuration-EUTRA IE shall be present.

If the Area Scope IE is not present in the MDT Configuration IE, the S-NG-RAN node shall consider that the MDT Configuration is applied to all PLMNs indicated in the MDT PLMN List, as described in TS 32.422. If the PNI-NPN Area Scope of MDT IE is included in the MDT Configuration-NR IE included in the TRACE START message, the S-NG-RAN node shall, if supported, use it to derive the MDT area scope for MDT measurement collection in PNI-NPN. Upon reception of the PNI-NPN Area Scope of MDT IE, the S-NG-RAN node shall consider that the area scope for MDT measurement collection of PNI-NPN areas is defined only by the areas included in the PNI-NPN Area Scope of MDT IE.

If the Trace Activation IE is not included in the TRACE START message, the S-NG-RAN node shall ignore the message. If both the PNI-NPN Area Scope of MDT IE and the Area Scope of MDT-NR IE are included in the MDT Configuration-NR IE in the TRACE START message, and the Area Scope of MDT-NR IE is set to "PNI-NPN based", the S-NG-RAN node shall, if supported, use the Area Scope of MDT-NR IE to derive the MDT area scope for MDT measurement collection in PNI-NPN areas, and ignore the PNI-NPN Area Scope of MDT IE. If the PNI-NPN Area Scope of MDT IE is included in the MDT Configuration-NR IE in the TRACE START message, and the Area Scope of MDT-NR IE is not included, the target NG-RAN node shall ignore the PNI-NPN Area Scope of MDT IE, and consider that the MDT Configuration for NR is applied to all PLMNs indicated in the MDT PLMN List described in TS 32.422.

The purpose of the Deactivate Trace procedure is to allow the M-NG-RAN node to request the S-NG-RAN node to stop the trace session for the indicated trace reference. The procedure uses UE-associated signalling.

The Deactivate Trace procedure is initiated by the M-NG-RAN by sending the DEACTIVATE TRACE to the S-NG-RAN node for that specific UE. Upon reception of the DEACTIVATE TRACE message, the S-NG-RAN shall stop the trace session for the indicated trace reference in the NG-RAN Trace ID IE.

Void.

The purpose of the Cell Traffic Trace procedure is to send the allocated Trace Recording Session Reference and the Trace Reference to the M-NG-RAN node. The procedure uses UE-associated signalling.

The procedure is initiated with a CELL TRAFFIC TRACE message sent from the S-NG-RAN node to the M-NG-RAN node. If the Privacy Indicator IE set to "Immediate MDT" is included in the message, the M-NG-RAN node shall take the information into account for anonymisation of MDT data as specified in TS 32.422.

The purpose of the SCG Failure Information Report procedure is to provide SCG mobility related information to the S-NG-RAN node. The procedure uses UE-associated signalling.

The M-NG-RAN node initiates the procedure by sending the SCG FAILURE INFORMATION REPORT message to the S-NG-RAN node. Upon receiving the message, the S-NG-RAN node shall assume that a PSCell change failure event was detected. The SCG FAILURE INFORMATION REPORT message may include:

• the SN Mobility Information IE, if the SN Mobility Information IE was sent for the PSCell change procedure from the S-NG-RAN node;
• the Source PSCell CGI IE, if the Source PSCell CGI IE was sent for the PSCell change procedure from the S-NG-RAN node.

If the SCG FAILURE INFORMATION REPORT message includes the Source PSCell CGI IE, the S-NG-RAN node shall, if supported, store the information. If the SCG FAILURE INFORMATION REPORT message includes the Failed PSCell CGI IE, the S-NG-RAN node shall, if supported, store the information and act as specified in TS 38.300. If received, the S-NG-RAN node uses the above information for SCG failure reason detection and optimisation.

Not applicable.

Void.

The purpose of the SCG Failure Transfer procedure is to indicate to the M-NG-RAN node that the root cause of the SCG failure may have occurred in the other nodes. The procedure uses UE-associated signalling.

S-NG-RAN node initiates the procedure by sending the SCG FAILURE TRANSFER message to M-NG-RAN node. If received, M-NG-RAN node uses the information according to TS 38.300.

Not applicable.

Void.

This procedure is used by the M-NG-RAN node to inform the source S-NG-RAN node that all the prepared PSCells are cancelled in the target S-NG-RAN node during a Conditional PSCell Change. The procedure uses UE-associated signalling.

The M-NG-RAN node initiates the procedure by sending the CONDITIONAL PSCELL CHANGE CANCEL message to the S-NG-RAN node including the Target S-NG-RAN node ID IE.

Not applicable.

Void.

This message is sent by the S-NG-RAN node to the M-NG-RAN node to inform of one or more performed random access procedures at the S-NG-RAN, due to which one or more RA reports are available at the UE.

The S-NG-RAN node initiates the procedure by sending the RACH INDICATION message to M-NG-RAN node. The RACH INDICATION message contains information concerning one or more performed random access procedures and existence of one or more RA report at the UE. Upon reception of the RACH INDICATION message the M-NG-RAN node may fetch the RA report from the UE.

Not applicable.