The purpose of the Bearer Context Modification Required procedure is to allow the gNB-CU-UP to modify a bearer context (e.g., due to local problems) and inform the gNB-CU-CP. The procedure uses UE-associated signalling.
The gNB-CU-UP initiates the procedure by sending the BEARER CONTEXT MODIFICATION REQUIRED message to the gNB-CU-CP. The gNB-CU-CP replies with the BEARER CONTEXT MODIFICATION CONFIRM message.
If the S1 DL UP Transport Layer InformationIE or the NG DL UP Transport Layer InformationIE or the Redundant NG DL UP Transport Layer InformationIE is contained in the BEARER CONTEXT MODIFICATION REQUIRED message, the gNB-CU-CP shall update the corresponding information.
If the gNB-CU-UP Cell Group Related ConfigurationIE is contained in the DRB To Modify ListIE in the BEARER CONTEXT MODIFICATION REQUIRED message, the gNB-CU-CP shall try to change the cell group related configuration accordingly. If the gNB-CU-CP is not able to update the requested cell group related configuration, it shall include the Cell Group InformationIE with the current cell group configuration in the DRB Modified ListIE in the BEARER CONTEXT MODIFICATION CONFIRM message.
If the User Plane Error IndicatorIE is included in the PDU Session Resource To Remove ListIE and is set to "GTP-U Error Indication Received" in the BEARER CONTEXT MODIFICATION REQUIRED message, the gNB-CU-CP shall, if supported, consider that the PDU session resource is released due to GTP-U Error Indication received over the NG-U tunnel and inform the SMF as specified in TS 23.527.
The purpose of the Bearer Context Release procedure is to allow the gNB-CU-CP to command the release of an UE-associated logical E1 connection. The procedure uses UE-associated signalling.
The gNB-CU-CP initiates the procedure by sending the BEARER CONTEXT RELEASE COMMAND message to the gNB-CU-UP. The gNB-CU-UP replies with the BEARER CONTEXT RELEASE COMPLETE message.
Upon reception of the BEARER CONTEXT RELEASE COMMAND message, the gNB-CU-UP shall release all related signalling and user data transport resources and reply with the BEARER CONTEXT RELEASE COMPLETE message.
The gNB-CU-UP shall, if supported, include the Retainability Measurements InformationIE in the BEARER CONTEXT RELEASE COMPLETE message, providing information on the removed DRB(s) for retainability measurements in the gNB-CU-CP, as described in TS 32.425 and TS 28.552.
The purpose of the Bearer Context Release Request procedure is to allow the gNB-CU-UP to request the gNB-CU-CP to release an UE-associated logical E1 connection. The procedure uses UE-associated signalling.
The gNB-CU-UP initiates the procedure by sending the BEARER CONTEXT RELEASE REQUEST message to the gNB-CU-CP.
If the DRB Status ListIE is included in the BEARER CONTEXT RELEASE REQUEST message, the gNB-CU-CP shall act as specified in TS 38.401.
Interactions with Bearer Context Release procedure:
The Bearer Context Release (gNB-CU-CP initiated) procedure may be initiated upon reception of a BEARER CONTEXT RELEASE REQUEST message.
Interaction with Bearer Context Modification (gNB-CU-CP initiated) procedure:
If applicable, as specified in TS 38.401, the gNB-CU-UP may receive, after having performed the Bearer Context Release Request (gNB-CU-UP initiated) procedure, the BEARER CONTEXT MODIFICATION REQUEST message including the Data Forwarding Information RequestIE within the DRBs To Modify ListIE.
This procedure is initiated by the gNB-CU-UP to indicate the inactivity/resumption of activity related to the UE. The procedure uses UE-associated signalling.
The gNB-CU-UP initiates the procedure by sending the BEARER CONTEXT INACTIVITY NOTIFICATION message to the gNB-CU-CP.
If the Activity Notification Level was set to "DRB" during the Bearer Context establishment, the gNB-CU-UP shall include the DRB Activity ListIE in the BEARER CONTEXT INACTIVITY NOTIFICATION message.
If the Activity Notification Level was set to "PDU Session" during the Bearer Context establishment, the gNB-CU-UP shall include the PDU Session Resource Activity ListIE in the BEARER CONTEXT INACTIVITY NOTIFICATION message.
If the Activity Notification Level was set to "UE" during the Bearer Context establishment, the gNB-CU-UP shall include the UE ActivityIE in the BEARER CONTEXT INACTIVITY NOTIFICATION message.
This procedure is initiated by the gNB-CU-UP to indicate the detection of DL data arrival for the UE, or indicate that a DL packet including a QFI value in the NG-U header not configured by the QoS Flows Information To Be SetupIE or the Flow Mapping InformationIE is received for the first time. The procedure uses UE-associated signalling.
The gNB-CU-UP initiates the procedure by sending the DL DATA NOTIFICATION message to the gNB-CU-CP.
If the PPIIE is included in the DL DATA NOTIFICATION message, the gNB-CU-CP shall use it for paging policy differentiation.
If the PDU Session To Notify ListIE is included in the DL DATA NOTIFICATION message, the gNB-CU-CP shall, if supported, either map the flow(s) included in PDU Session To Notify ListIE to the existing DRB or establish a new DRB for the flow(s).
If the MT-SDT InformationIE is included in the DL DATA NOTIFICATION message, the gNB-CU-CP shall, if supported, take it into account for MT-SDT paging.
If the SDT Data Size Threshold CrossedIE is included in the DL DATA NOTIFICATION message, the gNB-CU-CP shall, if supported, act as specified in TS 38.401.
This procedure is initiated by the gNB-CU-UP to request the gNB-CU-CP to execute a counter check procedure to verify the value of the PDCP COUNTs associated with DRBs established in the gNB-CU-UP.
The procedure uses UE-associated signalling.
The gNB-CU-UP initiates the procedure by sending the gNB-CU-UP COUNTER CHECK REQUEST message to the gNB-CU-CP.
Upon reception of the gNB-CU-UP COUNTER CHECK REQUEST message, the gNB-CU-CP may perform the RRC counter check procedure as defined in TS 33.501.
This procedure is initiated by the gNB-CU-UP to notify the gNB-CU-CP that an UL packet including a QFI value in the SDAP header not configured by the QoS Flows Information To Be SetupIE or the Flow Mapping InformationIE is received for the first time at the default DRB. The procedure uses UE-associated signalling.
This procedure is initiated by the gNB-CU-UP to report data volume served at the gNB-CU-UP, where the UE is connected to the 5GC. The procedure uses UE-associated signalling.
The purpose of the Early Forwarding SN Transfer procedure is to transfer, from the source gNB-CU-UP to the source gNB-CU-CP, DL COUNT of the last PDCP SDU successfully delivered or transmitted to the UE, for the purpose of discarding early forwarded downlink PDCP SDUs during Conditional Handover or conditional PSCell change or conditional PSCell addition.
The procedure uses UE-associated signalling.
The source gNB-CU-UP initiates the procedure by sending the EARLY FORWARDING SN TRANSFER message.
The DRBs Subject To Early Forwarding ListIE included in the EARLY FORWARDING SN TRANSFER message contains the DRB ID(s) corresponding to the DRB(s) subject to early data forwarding during Conditional Handover or conditional PSCell change or conditional PSCell addition or subsequent CPAC.
For each DRB in the DRBs Subject To Early Forwarding ListIE, the value of the DL COUNT ValueIE indicates the DL COUNT of the last PDCP SDU successfully delivered in-sequence to the UE, if RLC-AM, and successfully transmitted, if RLC-UM.
If the source gNB-CU-CP receives this message for a UE for which no prepared Conditional Handover exists, the source gNB-CU-CP shall ignore the message.
This procedure is initiated by the gNB-CU-CP to inform the measurement results received from the UE to the gNB-CU-UP.
The procedure uses UE-associated signalling.