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Content for  TS 38.473  Word version:  16.3.1

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8.3  UE Context Management procedures

8.3.1  UE Context Setup

8.3.1.1  General

The purpose of the UE Context Setup procedure is to establish the UE Context including, among others, SRB,DRB, BH RLC channel, and SL DRB configuration. The procedure uses UE-associated signalling.

8.3.1.2  Successful Operation

Reproduction of 3GPP TS 38.473, Figure 8.3.1.2-1: UE Context Setup Request procedure: Successful Operation
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The gNB-CU initiates the procedure by sending UE CONTEXT SETUP REQUEST message to the gNB-DU. If the gNB-DU succeeds to establish the UE context, it replies to the gNB-CU with UE CONTEXT SETUP RESPONSE. If no UE-associated logical F1-connection exists, the UE-associated logical F1-connection shall be established as part of the procedure.
If the UE-CapabilityRAT-ContainerList IE is included in the UE CONTEXT SETUP REQUEST, the gNB-DU shall take this information into account for UE specific configurations.
If the servingCellMO IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall configure servingCellMO for the indicated SpCell accordingly.
If the SpCell UL Configured IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall configure UL for the indicated SpCell accordingly.
If the SCell To Be Setup List IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall consider it as a list of candidate SCells to be set up. If the SCell UL Configured IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall configure UL for the indicated SCell accordingly. If the servingCellMO IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall configure servingCellMO for the indicated SCell accordingly.
If the DRX Cycle IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall use the provided value from the gNB-CU.
If the UL Configuration IE in DRB to Be Setup Item IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall take it into account for UL scheduling.
If the SRB To Be Setup List IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall act as specified in TS 38.401. If Duplication Indication IE is contained in the SRB To Be Setup List IE, the gNB-DU shall, if supported, setup two RLC entities for the indicated SRB. If the Additional Duplication Indication IE is contained in the SRB To Be Setup List IE, the gNB-DU shall, if supported, setup the indicated RLC entities for the indicated SRB.
If the DRB To Be Setup List IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall act as specified in TS 38.401. If the QoS Flow Mapping Indication IE is included in the DRB To Be Setup List IE for a QoS flow, the gNB-DU may take it into account that only the uplink or downlink QoS flow is mapped to the indicated DRB.
If the BH Information IE is included in the UL UP TNL Information to be setup List IE for a DRB, the gNB-DU shall, if supported, use the indicated BAP Routing ID and BH RLC channel for transmission of the corresponding GTP-U packets to the IAB-donor, as specified in TS 38.340.
If the BH RLC Channel To Be Setup List IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall act as specified in TS 38.401. If the Traffic Mapping Information IE is included in the BH RLC Channel To Be Setup Item IEs IE for a BH RLC Channel, the gNB-DU shall, if supported, process the Traffic Mapping Information IE as follows:
  • if the IP to layer2 Traffic Mapping Info IE is included, the gNB-DU shall store the mapping information contained in the IP to layer2 Mapping Info To Add IE, if present, for the egress BH RLC channel identified by the BH RLC CH ID IE, and shall remove the previously stored mapping information as indicated by the IP to layer2 Mapping Info To Remove IE, if present. The gNB-DU shall use the mapping information stored for the mapping of IP traffic to layer 2, as specified in TS 38.340.
  • if the BAP layer BH RLC channel Mapping Info IE is included, the gNB-DU shall store the mapping information contained in the BAP layer BH RLC channel Mapping Info To Add IE, if present, for the egress BH RLC channel identified by the BH RLC CH ID IE, and shall remove the previously stored mapping information as indicated by the BAP layer BH RLC channel Mapping Info To Remove IE, if present. The gNB-DU shall use the mapping information stored when forwarding traffic on BAP-layer, as specified in TS 38.340.
If two UL UP TNL Information IEs are included in UE CONTEXT SETUP REQUEST message for a DRB, gNB-DU shall include two DL UP TNL Information IEs in UE CONTEXT SETUP RESPONSE message and setup two RLC entities for the indicated DRB. gNB-CU and gNB-DU use the UL UP TNL Information IEs and DL UP TNL Information IEs to support packet duplication for intra-gNB-DU CA as defined in TS 38.470. The first UP TNL Information IE of the two UP TNL Information IEs is for the primary path.
If one or two Additional PDCP Duplication UP TNL Information IEs are included in the UE CONTEXT SETUP REQUEST message for a DRB, the gNB-DU shall, if supported, include one or two Additional PDCP Duplication UP TNL Information IEs in the UE CONTEXT SETUP RESPONSE message and setup one or two additional RLC entities for the indicated DRB. The gNB-CU and the gNB-DU use the Additional PDCP Duplication UP TNL Information IEs to support packet duplication for intra-gNB-DU CA as defined in TS 38.470.
If Duplication Activation IE is included in the UE CONTEXT SETUP REQUEST message for a DRB, gNB-DU should take it into account when activating/deactivating CA based PDCP duplication for the DRB. If the RLC Duplication State List IE is included in the RLC Duplication Information IE contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, take it into account when activating/deactivating CA based PDCP duplication for the DRB with more than two RLC entities.
If DC Based Duplication Configured IE is included in the UE CONTEXT SETUP REQUEST message for a DRB, gNB-DU shall regard that DC based PDCP duplication is configured for this DRB if the value is set to be "true" and it should take the responsibility of PDCP duplication activation/deactivation. If DC Based Duplication Activation IE is included in the UE CONTEXT SETUP REQUEST message for a DRB, gNB-DU should take it into account when activating/deactivating DC based PDCP duplication for this DRB. If the RLC Duplication State List IE is included in the RLC Duplication Information IE contained in the UE CONTEXT SETUP REQUEST message for a DRB, the gNB-DU shall, if supported, take it into account when activating/deactivating DC based PDCP duplication for the DRB with more than two RLC entities. If the Primary Path Indication IE is included in the RLC Duplication Information IE, the gNB-DU shall, if supported, take it into account when performing DC based PDCP duplication for the DRB with more than two RLC entities.
If UL PDCP SN length IE is included in the UE CONTEXT SETUP REQUEST message for a DRB, gNB-DU shall, if supported, store this information and use it for lower layer configuration.
For EN-DC operation, and if the Subscriber Profile ID for RAT/Frequency priority IE is received from an MeNB, the UE CONTEXT SETUP REQUEST message shall contain the Subscriber Profile ID for RAT/Frequency priority IE. If the Additional RRM Policy Index IE is received from an MeNB, the UE CONTEXT SETUP REQUEST message shall, if supported, contain the Additional RRM Policy Index IE. The gNB-DU shall store the received Subscriber Profile ID for RAT/Frequency priority in the UE context and use it as defined in TS 36.300. The gNB-DU shall, if supported, store the received Additional RRM Policy Index in the UE context and use it as defined in TS 36.300.
If the Index to RAT/Frequency Selection Priority IE is available at the gNB-CU, the Index to RAT/Frequency Selection Priority IE shall be included in the UE CONTEXT SETUP REQUEST. The gNB-DU may use it for RRM purposes.
The gNB-DU shall report to the gNB-CU, in the UE CONTEXT SETUP RESPONSE message, the result for all the requested DRBs, SRBs and BH RLC channels in the following way:
  • 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 to Setup List IE;
  • A list of SRBs which failed to be established shall be included in the SRB Failed to Setup List IE.
  • A list of successfully established SRBs with logical channel identities for primary path shall be included in the SRB Setup List IE only if CA based PDCP duplication is initiated for the concerned SRBs.
  • A list of BH RLC channels which are successfully established shall be included in the BH RLC Channel Setup List IE;
  • A list of BH RLC channels which failed to be established shall be included in the BH RLC Channel Failed to be Setup List IE;
  • A list of SL DRBs which are successfully established shall be included in the SL DRB Setup List IE;
  • A list of SL DRBs which failed to be established shall be included in the SL DRB Failed to Setup List IE.
When the gNB-DU reports the unsuccessful establishment of a DRB or SRB or SL DRB, the cause value should be precise enough to enable the gNB-CU to know the reason for the unsuccessful establishment.
For EN-DC operation, the gNB-CU shall include in the UE CONTEXT SETUP REQUEST the E-UTRAN QoS IE. The allocation of resources according to the values of the Allocation and Retention Priority IE included in the E-UTRAN QoS IE shall follow the principles described for the E-RAB Setup procedure in TS 36.413.
For NG-RAN operation, the gNB-CU shall include in the UE CONTEXT SETUP REQUEST the DRB Information IE.
For DC operation, the CG-ConfigInfo IE shall be included in the CU to DU RRC Information IE at the gNB acting as secondary node. If the CG-ConfigInfo IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall regard it as a reconfiguration with sync as defined in TS 38.331.
For sidelink operation, the CG-ConfigInfo IE shall be included in the CU to DU RRC Information IE if the gNB-CU receives sidelink related UE information from UE. If the CG-ConfigInfo IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall regard it as an indication of V2X sidelink information as defined in TS 38.331.
If the HandoverPreparationInformation IE is included in the CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU of the gNB acting as master node shall regard it as a reconfiguration with sync as defined in TS 38.331. The gNB-CU shall only initiate the UE Context Setup procedure for handover or secondary node addition when at least one DRB is setup for the UE.
If the received CU to DU RRC Information IE does not include source cell group configuration, the gNB-DU shall generate the cell group configuration using full configuration. Otherwise, delta configuration is allowed.
If the gNB-CU includes the SMTC information of the measured frequency(ies) in the MeasurementTimingConfiguration IE of the CU to DU RRC Information IE that is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall generate the measurement gaps based on the received SMTC information. Then the gNB-DU shall send the measurement gaps information to the gNB-CU in the MeasGapConfig IE of the DU to CU RRC Information IE that is included in the UE CONTEXT SETUP RESPONSE message.
If the MeasConfig IE is included in the CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall deduce that changes to the measurements configuration need to be applied. If the measObjectToAddModList IE is included in the MeasConfig IE, then the frequencies added in such IE are to be activated. Then the gNB-DU shall decide if measurement gaps are needed or not and, if needed, the gNB-DU shall send the measurement gaps information to the gNB-CU in the MeasGapConfig IE of the DU to CU RRC Information IE that is included in the UE CONTEXT SETUP RESPONSE message. If the measObjectToRemoveList IE is included in the MeasConfig IE, the gNB-DU shall ignore it.
For EN-DC operation, if the gNB-CU includes the Resource Coordination Transfer Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, use it for the purpose of resource coordination. If the Ignore PRACH Configuration IE is present and set to "true" the E-UTRA PRACH Configuration IE in the UE CONTEXT SETUP REQUEST message shall be ignored. If the gNB-CU received the MeNB Resource Coordination Information as defined in TS 36.423, it shall transparently transfer it to the gNB-DU via the Resource Coordination Transfer Container IE in the UE CONTEXT SETUP REQUEST message. The gNB-DU shall use the information received in the Resource Coordination Transfer Container IE for reception of MeNB Resource Coordination Information at the gNB acting as secondary node as described in TS 36.423. If the Resource Coordination E-UTRA Cell Information IE is included in the Resource Coordination Transfer Information IE, the gNB-DU shall store the information replacing previously received information for the same E-UTRA cell, and use the stored information for the purpose of resource coordination.
For NGEN-DC or NE-DC operation, if the gNB-CU includes the Resource Coordination Transfer Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, use it for the purpose of resource coordination. If the gNB-CU received the MR-DC Resource Coordination Information as defined in TS 38.423, it shall transparently transfer it to the gNB-DU via the Resource Coordination Transfer Container IE in the UE CONTEXT SETUP REQUEST message. The gNB-DU shall use the information received in the Resource Coordination Transfer Container IE for reception of MR-DC Resource Coordination Information at the gNB as described in TS 38.423.
The UEAssistanceInformation IE shall be included in CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message if the gNB-CU received this IE from the UE; if the UEAssistanceInformation IE is included in the CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, take it into account when configuring resources for the UE.
The UEAssistanceInformationEUTRA IE shall be included in CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message if the gNB-CU received this IE from the UE; if the UEAssistanceInformationEUTRA IE is included in the CU to DU RRC Information IE in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, take it into account when configuring LTE sidelink resources for the UE.
If the Resource Coordination Transfer Container IE is included in the UE CONTEXT SETUP RESPONSE, the gNB-CU shall transparently transfer this information for the purpose of resource coordination as described in TS 36.423, TS 38.423.
If the Masked IMEISV IE is contained in the UE CONTEXT SETUP REQUEST message the gNB-DU shall, if supported, use it to determine the characteristics of the UE for subsequent handling.
If the SCell Failed To Setup List IE is contained in the UE CONTEXT SETUP RESPONSE message, the gNB-CU shall regard the corresponding SCell(s) failed to be set up with an appropriate cause value for each SCell failed to setup.
If the Inactivity Monitoring Request IE is contained in the UE CONTEXT SETUP REQUEST message, gNB-DU may consider that the gNB-CU has requested the gNB-DU to perform UE inactivity monitoring. If the Inactivity Monitoring Response IE is contained in the UE CONTEXT SETUP RESPONSE message and set to "Not-supported", the gNB-CU shall consider that the gNB-DU does not support UE inactivity monitoring for the UE.
If the CellGroupConfig IE is included in the DU to CU RRC Information IE contained in the UE CONTEXT SETUP RESPONSE message, the gNB-CU shall perform RRC Reconfiguration or RRC connection resume as described in TS 38.331. The CellGroupConfig IE shall transparently be signaled to the UE as specified in TS 38.331.
If the Full Configuration IE is contained in the UE CONTEXT SETUP RESPONSE message, the gNB-CU shall consider that the gNB-DU has generated the CellGroupConfig IE using full configuration.
If the C-RNTI IE is included in the UE CONTEXT SETUP RESPONSE, the gNB-CU shall consider that the C-RNTI has been allocated by the gNB-DU for this UE context.
The UE Context Setup Procedure is not used to configure SRB0.
If the UE CONTEXT SETUP REQUEST message contains the RRC-Container IE, the gNB-DU shall send the corresponding RRC message to the UE via SRB1.
If the Notification Control IE is included in the DRB to Be Setup List IE contained in the UE CONTEXT SETUP REQUEST message and it is set to active, the gNB-DU shall, if supported, monitor the QoS of the DRB and notify the gNB-CU if the QoS cannot be fulfilled any longer or if the QoS can be fulfilled again. The Notification Control IE can only be applied to GBR bearers.
If the UL PDU Session Aggregate Maximum Bit Rate IE is included in the QoS Flow Level QoS Parameters IE contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall store the received UL PDU Session Aggregate Maximum Bit Rate and use it when enforcing uplink traffic policing for non-GBR Bearers for the concerned UE as specified in TS 23.501.
The gNB-DU shall store the received gNB-DU UE Aggregate Maximum Bit Rate Uplink and use it for non-GBR Bearers for the concerned UE.
If the UE CONTEXT SETUP REQUEST message contains the QoS Flow Mapping Indication IE, the gNB-DU may take it into account that only the uplink or downlink QoS flow is mapped to the DRB.
If the UE CONTEXT SETUP REQUEST message contains the New gNB-CU UE F1AP ID IE, the gNB-DU shall, if supported, replace the value received in the gNB-CU UE F1AP ID IE by the value of the New gNB-CU UE F1AP ID and use it for further signalling.
If the RAN UE ID IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall store and replace any previous information received.
If the Trace Activation IE is included in the UE CONTEXT SETUP REQUEST message the gNB-DU shall, if supported, initiate the requested trace function as described in TS 32.422.
In particular, the gNB-DU shall, if supported:
  • if the Trace Activation IE includes the MDT Activation IE set to "Immediate MDT and Trace", initiate the requested trace session and MDT session as described in TS 32.422;
  • if the Trace Activation IE includes the MDT Activation IE set to "Immediate MDT Only", initiate the requested MDT session as described in TS 32.422 and the gNB-DU shall ignore Interfaces To Trace IE, and Trace Depth IE. If the Management Based MDT PLMN List IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, store the received information in the UE context, and use this information to allow subsequent selection of the UE for management based MDT defined in TS 32.422.
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 UE CONTEXT SETUP REQUEST message, the gNB-DU shall store this information, and, if supported, perform delay measurement and QoS monitoring, as specified in TS 23.501.
If the UE CONTEXT SETUP REQUEST message contains the Configured BAP Address IE, the gNB-DU shall, if supported, store this BAP address configured for the corresponding child IAB-node and use it as specified in TS 38.401.
If the BAP Control PDU Channel IE is included in the BH RLC Channel to be Setup List IE, the gNB-DU shall, if supported, consider that the configured BH RLC channel can be used to transmit BAP Control PDUs, and use this BH RLC channel as specified in TS 38.340.
If the NR V2X Services Authorized IE is contained in the UE CONTEXT SETUP REQUEST message and it contains one or more IEs set to "authorized", the gNB-DU node shall, if supported, consider that the UE is authorized for the relevant service(s).
If the LTE V2X Services Authorized IE is contained in the UE CONTEXT SETUP REQUEST message and it contains one or more IEs set to "authorized", the gNB-DU node shall, if supported, consider that the UE is authorized for the relevant service(s).
If the NR UE Sidelink Aggregate Maximum Bit Rate IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, use it for the concerned UE's sidelink communication in network scheduled mode for NR V2X services.
If the LTE UE Sidelink Aggregate Maximum Bit Rate IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, use it for the concerned UE's sidelink communication in network scheduled mode for LTE V2X services.
If the PC5 Link Aggregate Bit Rate IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, use it for the concerned UE's sidelink communication in network scheduled mode for NR V2X services as defined in TS 23.287.
If the TSC Traffic Characteristics IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall, if supported, take into account the corresponding information received in the TSC Traffic Characteristics IE.
If the Conditional Inter-DU Mobility Information IE is included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall consider that the request concerns a conditional handover or conditional PSCell change for the included SpCell ID IE and shall include it as the Requested Target Cell ID IE in the UE CONTEXT SETUP RESPONSE message. The gNB-DU shall regard it as a reconfiguration with sync as defined in TS 38.331.
If the Target gNB-DU UE F1AP ID IE is contained in the Conditional Inter-DU Mobility Information IE included in the UE CONTEXT SETUP REQUEST message, then the gNB-DU shall replace the existing prepared conditional handover or conditional PSCell change identified by the Target gNB-DU UE F1AP ID IE and the SpCell ID IE.
If the Serving NID IE is contained in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall combine the Serving NID IE with the Serving PLMN IE to identify the serving NPN, and may take it into account for UE context establishment.
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8.3.1.3  Unsuccessful OperationWord‑p. 44
Reproduction of 3GPP TS 38.473, Figure 8.3.1.3-1: UE Context Setup Request procedure: unsuccessful Operation
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If the gNB-DU is not able to establish an F1 UE context, or cannot even establish one bearer it shall consider the procedure as failed and reply with the UE CONTEXT SETUP FAILURE message. If the Conditional Inter-DU Mobility Information IE was included in the UE CONTEXT SETUP REQUEST message, the gNB-DU shall include the received SpCell ID IE as the Requested Target Cell ID IE in the UE CONTEXT SETUP FAILURE message.
If the gNB-DU is not able to accept the SpCell ID IE in UE CONTEXT SETUP REQUEST message, it shall reply with the UE CONTEXT SETUP FAILURE message with an appropriate cause value. Further, if the Candidate SpCell List IE is included in the UE CONTEXT SETUP REQUEST message and the gNB-DU is not able to accept the SpCell ID IE, the gNB-DU shall, if supported, include the Potential SpCell List IE in the UE CONTEXT SETUP FAILURE message and the gNB-CU should take this into account for selection of an opportune SpCell. The gNB-DU shall include the cells in the Potential SpCell List IE in a priority order, where the first cell in the list is the one most desired and the last one is the one least desired (e.g., based on load conditions). If the Potential SpCell List IE is present but no Potential SpCell Item IE is present, the gNB-CU should assume that none of the cells in the Candidate SpCell List IE are acceptable for the gNB-DU.
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8.3.1.4  Abnormal Conditions

If the gNB-DU receives a UE CONTEXT SETUP REQUEST message containing a E-UTRAN QoS IE for a GBR QoS DRB but where the GBR QoS Information IE is not present, the gNB-DU shall report the establishment of the corresponding DRB as failed in the DRB Failed to Setup List IE of the UE CONTEXT SETUP RESPONSE message with an appropriate cause value. If the gNB-DU receives a UE CONTEXT SETUP REQUEST message containing a DRB QoS IE for a GBR QoS DRB but where the GBR QoS Flow Information IE is not present, the gNB-DU shall report the establishment of the corresponding DRBs as failed in the DRB Failed to Setup List IE of the UE CONTEXT SETUP RESPONSE message with an appropriate cause value.
If the Delay Critical IE is included in the Dynamic 5QI Descriptor IE within the DRB QoS IE in the UE CONTEXT SETUP REQUEST message and is set to the value "delay critical" but the Maximum Data Burst Volume IE is not present, the gNB-DU shall report the establishment of the corresponding DRB as failed in the DRB Failed to Setup List IE of the of the UE CONTEXT SETUP RESPONSE message with an appropriate cause value.
In case of "CHO-replace" when the Target gNB-DU UE F1AP ID IE is included, if the candidate cell in the SpCell ID IE included in the UE CONTEXT SETUP REQUEST message was not prepared using the same UE-associated signaling connection, the gNB-DU shall ignore this candidate cell.
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