8.3 Bearer Context Management procedures

37.4833GPPE1 Application Protocol (E1AP)Release 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.3.1 Bearer Context Setup

8.3.1.1 General

The purpose of the Bearer Context Setup procedure is to allow the gNB-CU-CP to establish a bearer context in the gNB-CU-UP. The procedure uses UE-associated signalling.

8.3.1.2 Successful Operation

Figure 8.3.1.2-1: Bearer Context Setup procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the BEARER CONTEXT SETUP REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to establish the requested resources, it replies to the gNB-CU-CP with the BEARER CONTEXT SETUP RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the BEARER CONTEXT SETUP RESPONSE message, the result for all the requested resources in the following way:

For E-UTRAN:

– A list of DRBs which are successfully established shall be included in the DRB Setup List IE;

– A list of DRBs which failed to be established shall be included in the DRB Failed List IE;

For NG-RAN:

– A list of PDU Session Resources which are successfully established shall be included in the PDU Session Resource Setup List IE;

– A list of PDU Session Resources which failed to be established shall be included in the PDU Session Resource Failed List IE;

– For each established PDU Session Resource, a list of DRBs which are successfully established shall be included in the DRB Setup List IE;

– For each established PDU Session Resource, a list of DRBs which failed to be established shall be included in the DRB Failed List IE;

– For each established DRB, a list of QoS Flows which are successfully established shall be included in the Flow Setup List IE;

– For each established DRB, a list of QoS Flows which failed to be established shall be included in the Flow Failed List IE;

When the gNB-CU-UP reports the unsuccessful establishment of a PDU Session Resource, DRB or QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment.

If the Existing Allocated NG DL UP Transport Layer Information IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may re-use the indicated resources already allocated for this bearer context. If the gNB-CU-UP decides to re-use the indicated resources, it shall include the NG DL UP Unchanged IE in the BEARER CONTEXT SETUP RESPONSE message.

If the PDU Session Resource DL Aggregate Maximum Bit Rate IE is contained in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store and use the information for the down link traffic policing for the Non-GBR QoS flows for the concerned UE as specified in TS 23.501 [20].

If the Data Forwarding Information Request IE, PDU Session Data Forwarding Information Request IE or the DRB Data Forwarding Information Request IE are included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall include the requested forwarding information in the Data Forwarding Information Response IE, PDU Session Data Forwarding Information Response IE or the DRB Data Forwarding Information Response IE in the BEARER CONTEXT SETUP RESPONSE message.

If the DL UP Parameters IE is contained in the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall configure the corresponding information.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection or ciphering, respectively, for the concerned PDU session and shall notify whether it performed the user plane integrity protection or ciphering by including the Integrity Protection Result IE or Confidentiality Protection Result IE, respectively, in the PDU Session Resource Setup List IE of the BEARER CONTEXT SETUP RESPONSE message.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "required", then the gNB-CU-UP shall perform user plane integrity protection or ciphering, respectively, for the concerned PDU Session. If the gNB-CU-UP cannot perform the user plane integrity protection or ciphering, it shall reject the setup of the PDU Session Resources with an appropriate cause value.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message:

– if the Integrity Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane integrity protection for the concerned PDU session;

– if the Confidentiality Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane ciphering for the concerned PDU session.

For E-UTRAN: – For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection for the concerned DRB and notify whether it performed the user plane integrity protection by including the Integrity Protection Result IE, in the DRB Setup List IE of the BEARER CONTEXT SETUP RESPONSE message.

– For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE is set to "required", then the gNB-CU-UP shall, if supported, perform user plane integrity protection for the concerned DRB. If the gNB-CU-UP cannot perform the user plane integrity protection, it shall reject the setup of the DRB with an appropriate cause value.

For each PDU session, if the Data Forwarding to E-UTRAN Information List IE is included in the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, use it for inter-system data forwarding from 5GS to EPS as specified in TS38.300 [8].

If the UE DL Maximum Integrity Protected Data Rate IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall use this value when enforcing the maximum integrity protected data rate for the UE.

If the Bearer Context Status Change IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider the UE RRC state and act as specified in TS 38.401 [2]. If the Bearer Context Status Change IE is set to "ResumeforSDT", the gNB-CU-UP shall, if supported, consider that DRBs not configured with SDT are suspended after being established.

For each requested DRB, if the PDCP Duplication IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, then the gNB-CU-UP shall include two UP Transport Layer Information IEs in the BEARER CONTEXT SETUP RESPONSE message to support packet duplication. If only one cell group is included in the Cell Group Information IE for the concerned DRB, then the gNB-CU-UP shall consider that the first UP Transport Layer Information IE of the two UP Transport Layer Information IEs is for the primary path.

For each requested DRB, if the Additional PDCP duplication Information IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, then the gNB-CU-UP shall, if supported, include the same number of UP Transport Layer Information IEs indicated by the Additional PDCP duplication Information IE in the BEARER CONTEXT SETUP RESPONSE message to support packet duplication. If only one cell group is included in the Cell Group Information IE for the concerned DRB, then the gNB-CU-UP shall consider that the first UP Transport Layer Information IE of these UP Transport Layer Information IEs is for the primary path. If more than one cell group is included in the Cell Group Information IE, then the gNB-CU-UP shall consider that the number of duplication tunnels for each cell group is indicated by the Number of tunnels IE, and that the first UP Transport Layer Information IE for each cell group is for the primary path or the split secondary path.

If the PDCP SN Status Information IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account and act as specified in TS 38.401 [2].

If the QoS Flow Mapping Indication IE is contained in the QoS Flows Information To Be Setup IE within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take it into account that only the uplink or downlink QoS flow is mapped to the DRB.

If the QoS Flows Remapping IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message for a DRB and set to "update", the gNB-CU-UP shall, if supported, consider that QoS flows mapped for the DRB is updated to the QoS flow(s) included in the QoS Flows Information To Be Setup IE after finishing handling forwarded PDCP SDUs during an intra-system handover procedure. If the QoS Flows Remapping IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message for a DRB and set to "source configuration", the gNB-CU-UP shall, if supported, consider that no QoS flow is mapped to the DRB after finishing handling forwarded PDCP SDUs over that DRB during an intra-system handover procedure and ignore the information included in the QoS Flows Information To Be Setup IE for the concerned DRB.

For each PDU Session Resource, if the Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message and the Common Network Instance IE is not included, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501 [20].

For each PDU session, if the Common Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501 [20].

For each PDU session, if the Redundant NG UL UP Transport Layer Information IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it as the uplink termination point of the redundant tunnel for the user plane data of those QoS flows in this PDU session which need redundant transmission as described in TS 23.501 [20], and it shall include the Redundant NG DL UP Transport Layer Information IE in the PDU Session Resource Setup List IE in the BEARER CONTEXT SETUP RESPONSE message.

For each PDU Session Resource, if the Redundant Common Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource for the redundant transmission as specified in TS 23.501 [20].

For each PDU session, if the Redundant QoS Flow Indicator IE is included in the QoS Flow QoS Parameters List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, consider it for the redundant transmission.

For each PDU session, if the Redundant PDU Session Information IE is included in the PDU Session Resource To Setup List IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, set up the redundant user plane resources, as specified in TS 23.501 [20] and include, if supported, the Used Redundant PDU Session Information IE in the PDU Session Resource Setup List IE in the BEARER CONTEXT SETUP RESPONSE message. If the PDU Session Pair ID IE is included in the Redundant PDU Session Information IE, the gNB-CU-UP may use it to identify the paired PDU Sessions.

If UE Inactivity Timer IE or PDU session Inactivity Timer IE or DRB Inactivity Timer IE is contained in BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account when perform inactivity monitoring.

If the DRB QoS IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take it into account as specified in TS 28.552 [22].

If the gNB-DU-ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store the information received.

If the RAN UE ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store the information received.

For each successfully established DRB, the gNB-CU-UP shall provide, in the respective UL UP Parameters IE of the BEARER CONTEXT SETUP RESPONSE, one UL UP Transport Layer Information Item per cell group entry contained in the respective Cell Group Information IE of the BEARER CONTEXT SETUP REQUEST message.

If the Trace Activation IE is included in the BEARER CONTEXT SETUP REQUEST message the gNB-CU-UP shall, if supported, initiate the requested trace function as described in TS 32.422 [24]. In particular, the gNB-CU-UP shall, if supported:

– if the MDT Activation IE is set to "Immediate MDT Only", initiate the requested MDT session as described in TS 32.422 [24] and the gNB-CU-UP shall ignore Interfaces To Trace IE, and Trace Depth IE;

– if the MDT Activation IE is set to "Immediate MDT and Trace", initiate the requested trace session and MDT session as described in TS 32.422 [24];

If the Management Based MDT PLMN List IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store the received information, and use this information to allow subsequent selection of the UE for management based MDT defined in TS 32.422 [24].

For EN-DC, if the Subscriber Profile ID for RAT/Frequency priority IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300 [25]. If the Additional RRM Policy Index IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300 [25].

If the TSC Traffic Characteristics IE is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take into account the corresponding information received in the TSC Traffic Characteristics IE.

For each QoS flow whose DRB has been successfully established and the QoS Monitoring Request IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store this information, and, if supported, perform delay measurement and QoS monitoring, as specified in TS 23.501 [20]. If the QoS Monitoring Reporting Frequency IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store this information, and, if supported, use it for RAN part delay reporting.

If the BEARER CONTEXT SETUP REQUEST message contains the NPN Context Information IE the gNB-CU-UP shall, if supported, take it into account when allocating UP resources for the bearer context.

For each requested DRB, if the EHC Parameters IE is included in the PDCP Configuration IE, the gNB-CU-CP shall, if supported, also include ROHC Parameters IE in the PDCP Configuration IE in the BEARER CONTEXT SETUP REQUEST message, to enable the gNB-CU-UP to perform appropriate header compression.

If the EHC parameters IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take these parameters into account to perform appropriate header compression for the concerned DRB. If the EHC Downlink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-DL IE is set to ‘true’, the gNB-CU-UP shall, if supported, configure Ethernet header compression for downlink and continue the downlink EHC header compression protocol as specified in TS 38.331 [10]. If the EHC Downlink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-DL IE is set to ‘false’, the gNB-CU-UP shall, if supported, configure Ethernet header compression for downlink and reset the downlink EHC header compression protocol during PDCP re-establishment as specified in TS 38.331 [10]. If the EHC Uplink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-UL IE is set to ‘true’, the gNB-CU-UP shall, if supported, configure Ethernet header compression for uplink and continue the uplink EHC header compression protocol as specified in TS 38.331 [10]. If the EHC Uplink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-UL IE is set to ‘false’, the gNB-CU-UP shall, if supported, configure Ethernet header compression for uplink and resets the uplink EHC header compression protocol during PDCP re-establishment as specified in TS 38.331 [10].

If the DAPS Request Information IE is included for a DRB to be setup in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider that the request concerns a DAPS handover for that DRB and, if admitted, act as specified in TS 38.300 [4].

If the CHO Initiation IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider that the request concerns conditional handover or conditional PSCell change or conditional PSCell addition and act as specified in TS 38.401 [2].

If the MCG Offered GBR QoS Flow Information IE is contained in the QoS Flows Information To Be Setup IE within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take it into account when two cell groups are served by the gNB-CU-UP.

If the Additional Handover Information IE is included in the BEARER CONTEXT SETUP REQUEST message and set to “Discard PDCP SN”, the gNB-CU-UP shall, if supported, remove the forwarded PDCP SNs if received in the forwarded GTP-U packets, and deliver the forwarded PDCP SDUs to the UE, as specified in TS 38.300 [8].

If the Ignore Mapping Rule Indication IE is contained within the DRB To Setup List IE for a DRB in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, ignore the QoS flow mapping information indicated by the QoS Flows Information To Be Setup IE for the concerned DRB.

If the Direct Forwarding Path Availability IE set to "inter-system direct path available" is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, assign the UP Transport Layer Information for inter-system direct data forwarding from the appropriate address space, if applicable.

If the Direct Forwarding Path Availability IE set to “intra-system direct path available” is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, assign the UP Transport Layer Information for intra-system direct data forwarding from the appropriate address space, if applicable.

If the gNB-CU-UP UE E1AP ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may use it to identify the UE context as specified in TS 38.401 [2].

If the Data Forwarding Source IP Address IE is included in the DRB To Setup List E-UTRAN IE or in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed.

If the Data Forwarding Source IP Address IE is included in the DRB Setup List E-UTRAN IE or in the Flow Setup List IE within the DRB Setup List IE in the PDU Session Resource Setup List IE of the BEARER CONTEXT SETUP RESPONSE message, the gNB-CU-CP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed.

If the MDT Polluted Measurement Indicator IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP shall take this information into account as specified in TS 38.401 [2].

If the UE Slice Maximum Bit Rate List IE is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store and use the information for the downlink traffic policing for each concerned slice as specified in TS 23.501 [20].

If the UDC parameters IE is included in the PDCP Configuration IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take these parameters into account to perform appropriate uplink data compression for the concerned DRB.

If the SCG Activation Status IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account when handling DL data transfer as specified in TS 37.340 [19].

8.3.1.3 Unsuccessful Operation

Figure 8.3.1.3-1: Bearer Context Setup procedure: Unsuccessful Operation.

If the gNB-CU-UP cannot establish the requested bearer context, or cannot even establish one bearer, or cannot handle SCG with the indicated activated or deactivated status it shall consider the procedure as failed and respond with a BEARER CONTEXT SETUP FAILURE message and appropriate cause value.

8.3.1.4 Abnormal Conditions

If the gNB-CU-UP receives a BEARER CONTEXT SETUP REQUEST message containing a E-UTRAN QoS IE in the DRB To Setup List IE for a GBR QoS DRB but where the GBR QoS Information IE is not present, the gNB-CU-UP shall report the establishment of the corresponding DRB as failed in the DRB Failed List IE of the BEARER CONTEXT SETUP RESPONSE message with an appropriate cause value.

If the gNB-CU-UP receives a BEARER CONTEXT SETUP REQUEST message containing a QoS Flow Level QoS Parameters IE in the PDU Session Resource To Setup List IE for a GBR QoS Flow but where the GBR QoS Flow Information IE is not present, the gNB-CU-UP shall report the establishment of the corresponding QoS Flow as failed in the corresponding Flow Failed List IE of the BEARER CONTEXT SETUP RESPONSE message with an appropriate cause value.

8.3.2 Bearer Context Modification (gNB-CU-CP initiated)

8.3.2.1 General

The purpose of the Bearer Context Modification procedure is to allow the gNB-CU-CP to modify a bearer context in the gNB-CU-UP. The procedure uses UE-associated signalling.

8.3.2.2 Successful Operation

Figure 8.3.2.2-1: Bearer Context Modification procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the BEARER CONTEXT MODIFICATION REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to modify the bearer context, it replies to the gNB-CU-CP with the BEARER CONTEXT MODIFICATION RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the BEARER CONTEXT MODIFICATION RESPONSE message, the result for all the requested resources in the following way:

For E-UTRAN:

– A list of DRBs which are successfully established shall be included in the DRB Setup List IE;

– A list of DRBs which failed to be established shall be included in the DRB Failed List IE;

– A list of DRBs which are successfully modified shall be included in the DRB Modified List IE;

– A list of DRBs which failed to be modified shall be included in the DRB Failed To Modify List IE;

For NG-RAN:

– A list of PDU Session Resources which are successfully established shall be included in the PDU Session Resource Setup List IE;

– A list of PDU Session Resources which failed to be established shall be included in the PDU Session Resource Failed List IE;

– A list of PDU Session Resources which are successfully modified shall be included in the PDU Session Resource Modified List IE;

– A list of PDU Session Resources which failed to be modified shall be included in the PDU Session Resource Failed To Modify List IE;

– For each successfully established or modified PDU Session Resource, a list of DRBs which are successfully established shall be included in the DRB Setup List IE;

– For each successfully established or modified PDU Session Resource, a list of DRBs which failed to be established shall be included in the DRB Failed List IE;

– For each successfully modified PDU Session Resource, a list of DRBs which are successfully modified shall be included in the DRB Modified List IE;

– For each successfully modified PDU Session Resource, a list of DRBs which failed to be modified shall be included in the DRB Failed To Modify List IE;

– For each successfully established or modified DRB, a list of QoS Flows which are successfully established shall be included in the Flow Setup List IE;

– For each successfully established or modified DRB, a list of QoS Flows which failed to be established shall be included in the Flow Failed List IE;

If the Security Information IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the UE DL Aggregate Maximum Bit Rate IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the UE DL Maximum Integrity Protected Data Rate IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the Bearer Context Status Change IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall consider the UE RRC state and act as specified in TS 38.401 [2]. If the Bearer Context Status Change IE is set to "ResumeforSDT", the gNB-CU-UP shall consider that DRBs configured with SDT are resumed only and the other DRBs remain suspended.

If SDT Continue ROHC IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message and the value is set to “true”, the gNB-CU-UP shall, if supported, continue the ROHC for the SDT bearers for the UE.

If the Data Forwarding Information Request IE, PDU Session Data Forwarding Information Request IE or the DRB Data Forwarding Information Request IE are included in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall include the requested forwarding information in the Data Forwarding Information Response IE, PDU Session Data Forwarding Information Response IE or the DRB Data Forwarding Information Response IE in the BEARER CONTEXT MODIFICATION RESPONSE message.

If the PDU Session Data Forwarding Information IE is included in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, consider that data forwarding is applicable for the indicated QoS flows for the concerned PDU session.

If the PDCP Configuration IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information, except for the PDCP SN UL Size IE, the PDCP SN DL Size IE and the RLC mode IE which shall be ignored.

If the E-UTRAN QoS IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the PDCP SN Status Request IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall act as specified in TS 38.401 [2] and include the UL COUNT Value IE and the DL COUNT Value IE in the BEARER CONTEXT MODIFICATION RESPONSE message.

If the PDCP SN Status Information IE is contained in the DRB To Setup List IE or the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall take it into account and act as specified in TS 38.401 [2].

If the DL UP Parameters IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the Cell Group To Add IE or the Cell Group To Modify IE or the Cell Group To Remove IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall add or modify or remove the corresponding cell group.

If the PDU Session Resource DL Aggregate Maximum Bit Rate IE is contained in the PDU Session Resource To Setup List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall replace the information in the UE context and use it when enforcing downlink traffic policing for the non GBR QoS flows for the concerned UE, as specified in TS 23.501 [20].

If the PDU Session Resource DL Aggregate Maximum Bit Rate IE is contained in the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the SDAP Configuration IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

If the Flow Mapping Information IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the corresponding information.

For each requested DRB, if the PDCP Duplication IE or Additional PDCP duplication Information IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT MODIFICATION REQUEST message, then the gNB-CU-CP shall include two or more UP Transport Layer Information IEs in the BEARER CONTEXT MODIFICATION REQUEST message, and the gNB-CU-UP shall, if supported, also include two or more UP Transport Layer Information IEs in the BEARER CONTEXT MODIFICATION RESPONSE message to support packet duplication. If only one cell group is included in the Cell Group Information IE for the concerned DRB, then the gNB-CU-UP shall consider that the first UP Transport Layer Information IE of these UP Transport Layer Information IEs is for the primary path. If more than one cell group is included in the Cell Group Information IE, then the gNB-CU-UP shall consider that the number of duplication tunnels for each cell group is indicated by the Number of tunnels IE, and that the first UP Transport Layer Information IE for each cell group is for the primary path or the split secondary path.

For a certain DRB which was allocated with two or more GTP-U tunnels, if such DRB is modified and given one GTP-U tunnel via the Bearer Context Modification (gNB-CU-CP initiated) procedure, i.e. only one UP Transport Layer Information per Cell Group ID is present in DL UP Parameters IE for the concerned DRB, then the gNB-CU-UP shall consider that PDCP duplication is deconfigured for this DRB. If such Bearer Context Modification (gNB-CU-CP initiated) procedure occurs, the Duplication Activation IE shall not be included for the concerned DRB.

If the New UL TNL Information Required IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall include the new UP Transport Layer Information in the BEARER CONTEXT MODIFICATION RESPONSE message.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE or the Security Indication Modify IE is included in the PDU Session Resource To Modify List IE of the BEARER CONTEXT MODIFICATION REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection or ciphering, respectively, for the concerned PDU session and shall notify whether it performed the user plane integrity protection or ciphering by including the Integrity Protection Result IE or Confidentiality Protection Result IE, respectively, in the PDU Session Resource Setup List IE or the PDU Session Resource Modified List IE of the BEARER CONTEXT MODIFICATION RESPONSE message.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE or the Security Indication Modify IE is included in the PDU Session Resource To Modify List IE of the BEARER CONTEXT MODIFICATION REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "required", then the gNB-CU-UP shall perform user plane integrity protection or ciphering, respectively, for the concerned PDU Session. If the gNB-CU-UP cannot perform the user plane integrity protection or ciphering, it shall reject the setup of the PDU Session Resources with an appropriate cause value.

For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE or the Security Indication Modify IE is included in the PDU Session Resource To Modify List IE of the BEARER CONTEXT MODIFICATION REQUEST message:

– if the Integrity Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane integrity protection for the concerned PDU session;

– if the Confidentiality Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane ciphering for the concerned PDU session.

For E-UTRAN:

– For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT MODIFICATION REQUEST message, and the Integrity Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection for the concerned DRB and notify whether it performed the user plane integrity protection by including the Integrity Protection Result IE in the DRB Setup List IE of the BEARER CONTEXT MODIFICATION RESPONSE message.

– For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT MODIFICATION REQUEST message, and the Integrity Protection Indication IE is set to "required", then the gNB-CU-UP shall, if supported, perform user plane integrity protection for the concerned DRB. If the gNB-CU-UP cannot perform the user plane integrity protection, it shall reject the setup of the DRB with an appropriate cause value.

– For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT MODIFICATION REQUEST message and the Integrity Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane integrity protection for the concerned DRB.

For each PDU Session Resource, if the Network Instance IE is included in the PDU Session Resource To Setup List IE or the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message and the Common Network Instance IE is not included, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501 [20].

For each PDU session, if the Common Network Instance IE is included in the PDU Session Resource To Setup List IE or the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501 [20].

For each PDU session, if the Redundant NG UL UP Transport Layer Information IE is included in the PDU Session Resource To Setup List IE or the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, include the Redundant NG DL UP Transport Layer Information IE in the PDU Session Resource Setup List IE or the PDU Session Resource Modified List IE in the BEARER CONTEXT MODIFICATION RESPONSE message.

If the Redundant Common Network Instance IE is included in the PDU Session Resource To Setup List IE or the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource for the redundant transmission as specified in TS 23.501 [20].

For each PDU session for which the Redundant QoS Flow Indicator IE is included in QoS Flows Information To Be Setup IE contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if support, shall store and use it as specified in TS 23.501 [20].

For each PDU session, if the Redundant QoS Flow Indicator IE is set to false for all QoS flows, the gNB-CU-UP shall, if supported, stop the redundant transmission and release the redundant tunnel for the concerned PDU session as specified in TS 23.501 [20].

If the QoS Flow Mapping Indication IE is contained in the QoS Flow QoS Parameters List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, replace any previously received value and take it into account that only the uplink or downlink QoS flow is mapped to the DRB.

If the Data Discard Required IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message and the value is set to “Required”, the gNB-CU-UP shall consider that a RAN Paging Failure occurred for that UE. The gNB-CU-UP shall discard the user plane data for that UE and consider that the bearer context is still suspended.

If UE Inactivity Timer IE or PDU session Inactivity Timer IE or DRB Inactivity Timer IE is contained in BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall take it into account when perform inactivity monitoring.

If the S-NSSAI IE is contained in the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall store the corresponding information and replace any existing information.

If the DRB QoS IE is contained within the DRB To Setup List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, take it into account for each DRB, as specified in TS 28.552 [22].

If the DRB QoS IE is contained within the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, replace any previously received value and take it into account for each DRB, as specifed in TS 28.552 [22].

If the gNB-DU-ID IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall store and replace any previous information received.

If the RAN UE ID IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall store and replace any previous information received.

If the gNB-CU-UP receives a BEARER CONTEXT MODIFICATION REQUEST message including Activity Notification Level IE and its value does not match the current bearer context, the gNB-CU-UP shall ignore the Activity Notification Level IE and also the requested modification of inactivity timer.

For each successfully established DRB, the gNB-CU-UP shall provide, in the respective UL UP Parameters IE of the BEARER CONTEXT MODIFICATION RESPONSE, one UL UP Transport Layer Information Item per cell group entry contained in the respective Cell Group Information IE of the BEARER CONTEXT MODIFICATION REQUEST message.

If the Old QoS Flow List – UL End Marker expected IE is included in the PDU Session Resource To Modify List IE of the BEARER CONTEXT MODIFICATION REQUEST message for a DRB to be modified, the gNB-CU-UP shall consider that the source NG-RAN node has initiated QoS flow re-mapping and has not yet received SDAP end markers, as described in TS 38.300 [8]. The gNB-CU-UP shall consider that the Old QoS Flow List – UL End Marker expected IE only contains UL QoS flow information for QoS flows for which no SDAP end marker has been yet received on the source side.

For EN-DC, if the Subscriber Profile ID for RAT/Frequency priority IE is included in the BEARER CONTEXT MODIFICATION REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300 [25]. If the Additional RRM Policy Index IE is included in the BEARER CONTEXT MODIFICATION REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300 [25].

If there is at least one DRB removed by the gNB-CU-UP, the gNB-CU-UP shall, if supported, include the Retainability Measurements Information IE in the BEARER CONTEXT MODIFICATION RESPONSE message, providing information on the removed DRB(s) for retainability measurements in the gNB-CU-CP, as described in TS 32.425 [26] and TS 28.552 [22].

If the TSC Traffic Characteristics IE is included in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, take into account the corresponding information received in the TSC Traffic Characteristics IE.

For each QoS flow whose DRB has been successfully established or modified and the QoS Monitoring Request IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall store this information, and, if supported, perform delay measurement and QoS monitoring, as specified in TS 23.501 [20]. If the QoS Monitoring Reporting Frequency IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall store this information, and, if supported, use it for RAN part delay reporting.

For each requested DRB, if the QoS Mapping Information IE is contained in the DL UP Parameters IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall use it to set DSCP and/or flow label fields in the downlink IP packets which are transmitted through the GTP tunnels indicated by the UP Transport Layer Information IE. The Diffserv code point (DSCP) marking is performed as specified in TS 38.474 [28].

If the Early Forwarding COUNT Request IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall act as specified in TS 38.401 [2] and include the requested FIRST DL COUNT Value IE or DISCARD DL COUNT Value IE in the BEARER CONTEXT MODIFICATION RESPONSE message.

If the Early Forwarding COUNT Information IE is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall take it into account and act as specified in TS 38.401 [2].

If the Ignore Mapping Rule Indication IE is contained within the DRB To Setup List IE for a DRB in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, ignore the QoS flow mapping information indicated by the QoS Flows Information To Be Setup IE for the concerned DRB.

If the DAPS Request Information IE is included for a DRB to be modified in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall consider that the request concerns a DAPS handover for that DRB and, if admitted, act as specified in TS 38.300 [4].

If the Early Data Forwarding Indicator IE set to “stop” is contained in the DRB To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported and if already initiated, stop the early data forwarding for the concerned DRB. If the DRB Data forwarding information IE containing the DL Data Forwarding IE is included together in the DRB To Modify List IE, the gNB-CU-UP shall consider that the stop is only for the early data forwarding initiated toward that forwarding TNL.

If the MDT Polluted Measurement Indicator IE is included in the BEARER CONTEXT MODIFICATION REQUEST, the gNB-CU-UP shall take this information into account as specified in TS 38.401 [2].

If the UE Slice Maximum Bit Rate List IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, store and replace the previously provided UE Slice Maximum Bit Rate List by the received UE Slice Maximum Bit Rate List in the UE context, and use the received UE Slice Maximum Bit Rate List for the downlink traffic policing for each concerned slice as specified in TS 23.501 [20].

If the SCG Activation Status IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall take it into account when handling DL data transfer as specified in TS 37.340 [19].

If the UDC parameters IE is included in the PDCP Configuration IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, take these parameters into account to perform appropriate uplink data compression for the concerned DRB.

If the Data Forwarding Source IP Address IE is included in the DRB To Setup Modification List E-UTRAN IE or in the QoS Flow Level QoS Parameters IE within the PDU Session Resource To Setup Modification List IE and the PDU Session Resource To Modify List IE contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed.

If the Data Forwarding Source IP Address IE is included in the DRB Setup Modification List E-UTRAN IE or in the Flow Setup List IE within the PDU Session Resource Setup Modification List IE and the PDU Session Resource Modified List IE of the BEARER CONTEXT MODIFICATION RESPONSE message, the gNB-CU-CP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed.

If the Management Based MDT PLMN Modification List IE is contained in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, overwrite any previously stored Management Based MDT PLMN List information in the UE context and use the received information to determine subsequent selection of the UE for management based MDT defined in TS 32.422 [24].

Interaction with the Bearer Context Modification (gNB-CU-CP initiated)

If the BEARER CONTEXT MODIFICATION REQUEST message includes for a DRB in the DRB To Modify List IE the PDCP SN Status Request IE set to “requested” and if the gNB-CU-UP has not yet received a SDAP end marker packet for a QoS flow which has been previously re-configured to another DRB by means of a gNB-CU-CP initiated Bearer Context Modification procedure, the gNB-CU-UP shall includes the QoS Flow Identifier of that QoS flow in the Old QoS Flow List – UL End Marker expected IE in the PDU Session Resource Modified List IE in the BEARER CONTEXT MODIFICATION RESPONSE message.

8.3.2.3 Unsuccessful Operation

Figure 8.3.2.3-1: Bearer Context Modification procedure: Unsuccessful Operation.

If the gNB-CU-UP cannot successfully perform any of the requested bearer context modifications, or cannot handle SCG with the indicated activated or deactivated status, it shall respond with a BEARER CONTEXT MODIFICATION FAILURE message and appropriate cause value.

If the gNB-CU-UP receives a BEARER CONTEXT MODIFICATION REQUEST message containing the Security Indication Modify IE in the PDU Session Resource To Modify List IE for a PDU session that may result in the change of security status that has been applied but the DRBs that have been established for that PDU session are not requested to be released via the DRB To Remove List IEs as specified in TS 38.331 [10], then the gNB-CU-UP shall respond with a BEARER CONTEXT MODIFICATION FAILURE message and appropriate cause value.

8.3.2.4 Abnormal Conditions

If the gNB-CU-UP receives a BEARER CONTEXT MODIFICATION REQUEST message containing a E-UTRAN QoS IE in the DRB To Setup List or the DRB To Modify List IE for a GBR QoS DRB but where the GBR QoS Information IE is not present, the gNB-CU-UP shall report the addition or the modification of the corresponding DRB as failed in the DRB Failed List IE or the DRB Failed To Modify List IE of the BEARER CONTEXT MODIFICATION RESPONSE message with an appropriate cause value.

If the gNB-CU-UP receives a BEARER CONTEXT MODIFICATION REQUEST message containing a QoS Flow Level QoS Parameters IE in the PDU Session Resource To Setup List IE or the PDU Session Resource To Modify List IE for a GBR QoS Flow but where the GBR QoS Flow Information IE is not present, the gNB-CU-UP shall report the addition or the modification of the corresponding QoS Flow as failed in the corresponding Flow Failed List IE of the BEARER CONTEXT MODIFICATION RESPONSE message with an appropriate cause value.

8.3.3 Bearer Context Modification Required (gNB-CU-UP initiated)

8.3.3.1 General

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.

8.3.3.2 Successful Operation

Figure 8.3.3.2-1: Bearer Context Modification Required procedure: Successful Operation.

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 Information IE or the NG DL UP Transport Layer Information IE or the Redundant NG DL UP Transport Layer Information IE 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 Configuration IE is contained in the DRB To Modify List IE 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 Information IE with the current cell group configuration in the DRB Modified List IE in the BEARER CONTEXT MODIFICATION CONFIRM message.

8.3.3.3 Abnormal Conditions

Not applicable.

8.3.4 Bearer Context Release (gNB-CU-CP initiated)

8.3.4.1 General

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.

8.3.4.2 Successful Operation

Figure 8.3.4.2-1: Bearer Context Release procedure: Successful Operation.

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 Information IE 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 [26] and TS 28.552 [22].

8.3.4.3 Abnormal Conditions

Not applicable.

8.3.5 Bearer Context Release Request (gNB-CU-UP initiated)

8.3.5.1 General

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.

8.3.5.2 Successful Operation

Figure 8.3.5.2-1: Bearer Context Release Requset procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the BEARER CONTEXT RELEASE REQUEST message to the gNB-CU-CP.

If the DRB Status List IE is included in the BEARER CONTEXT RELEASE REQUEST message, the gNB-CU-CP shall act as specified in TS 38.401 [2].

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 [2], 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 Request IE within the DRBs To Modify List IE.

8.3.5.3 Abnormal Conditions

Not applicable.

8.3.6 Bearer Context Inactivity Notification

8.3.6.1 General

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.

8.3.6.2 Successful Operation

Figure 8.3.6.2-1: Bearer Context Inactivity Notification procedure: Successful Operation.

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 List IE 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 List IE 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 Activity IE in the BEARER CONTEXT INACTIVITY NOTIFICATION message.

8.3.6.3 Abnormal Conditions

Not applicable.

8.3.7 DL Data Notification

8.3.7.1 General

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 Setup IE or the Flow Mapping Information IE is received for the first time. The procedure uses UE-associated signalling.

8.3.7.2 Successful Operation

Figure 8.3.7.2-1: DL Data Notification procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the DL DATA NOTIFICATION message to the gNB-CU-CP.

If the PPI IE 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 List IE 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 List IE to the existing DRB or establish a new DRB for the flow(s).

NOTE: If a DL packet including a QFI value in the NG-U header not configured by the QoS Flows Information To Be Setup IE or the Flow Mapping Information IE is received, the gNB-CU-UP may deliver the DL packet via any existing configured DRB before it initiates DL Data Notification procedure.

8.3.7.3 Abnormal Conditions

Not applicable.

8.3.8 Data Usage Report

8.3.8.1 General

This procedure is initiated by the gNB-CU-UP to report data volume served at the gNB-CU-UP. The procedure uses UE-associated signalling.

8.3.8.2 Successful Operation

Figure 8.3.8.2-1: Data Usage Report procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the DATA USAGE REPORT message to the gNB-CU-CP.

8.3.8.3 Abnormal Conditions

Not applicable.

8.3.9 gNB-CU-UP Counter Check

8.3.9.1 General

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.

8.3.9.2 Successful Operation

Figure 8.3.9.2-1: gNB-CU-UP Counter Check procedure, successful operation.

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 [13].

8.3.9.3 Unsuccessful Operation

Not applicable.

8.3.9.4 Abnormal Conditions

Not applicable.

8.3.10 UL Data Notification

8.3.10.1 General

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 Setup IE or the Flow Mapping Information IE is received for the first time at the default DRB. The procedure uses UE-associated signalling.

8.3.10.2 Successful Operation

Figure 8.3.10.2-1: UL Data Notification procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the UL DATA NOTIFICATION message to the gNB-CU-CP.

8.3.10.3 Abnormal Conditions

Not applicable.

8.3.11 MR-DC Data Usage Report

8.3.11.1 General

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.

8.3.11.2 Successful Operation

Figure 8.3.11.2-1: MR-DC Data Usage Report procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the MR-DC DATA USAGE REPORT message to the gNB-CU-CP.

8.3.11.3 Abnormal Conditions

Not applicable.

8.3.12 Early Forwarding SN Transfer

8.3.12.1 General

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.

8.3.12.2 Successful Operation

Figure 8.3.12.2-1: Early Forwarding SN Transfer procedure: Successful Operation.

The source gNB-CU-UP initiates the procedure by sending the EARLY FORWARDING SN TRANSFER message.

The DRBs Subject To Early Forwarding List IE 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.

For each DRB in the DRBs Subject To Early Forwarding List IE, the value of the DL COUNT Value IE 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.

8.3.12.3 Unsuccessful Operation

Not applicable.

8.3.12.4 Abnormal Conditions

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.

8.3.13 GNB-CU-CP Measurement Results Information

8.3.13.1 General

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.

8.3.13.2 Successful Operation

Figure 8.3.13.2-1: GNB-CU-CP Measurement Results Information procedure. Successful operation.

The gNB-CU-CP initiates the procedure by sending a GNB-CU-CP MEASUREMENT RESULTS INFORMATION message.

8.3.13.3 Abnormal Conditions

Not applicable.