Content for  TS 38.473  Word version:  17.3.0

The purpose of the UE Context Modification procedure is to modify the established UE Context, e.g., establishing, modifying and releasing radio resources or sidelink resources. This procedure is also used to command the gNB-DU to stop data transmission for the UE for mobility (see TS 38.401). The procedure uses UE-associated signalling.

The UE CONTEXT MODIFICATION REQUEST message is initiated by the gNB-CU. Upon reception of the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall perform the modifications, and if successful reports the update in the UE CONTEXT MODIFICATION RESPONSE message. If the SpCell ID IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall replace any previously received value and regard it as a reconfiguration with sync as defined in TS 38.331. If the ServCellIndex IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall take this into account for the indicated SpCell. If the SpCell UL Configured IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall configure UL for the indicated SpCell accordingly. If the servingCellMO IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall configure servingCellMO for the indicated SpCell accordingly. If the SCell To Be Setup List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall consider it as a list of candidate SCells to be set up. If the SCell To Be Setup List IE is included in the UE CONTEXT MODIFICATION REQUEST message and the indicated SCell(s) are already setup, the gNB-DU shall replace any previously received value. If the SCell UL Configured IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall configure UL for the indicated SCell accordingly. If the servingCellMO IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall configure servingCellMO for the indicated SCell accordingly. If the SCell To Be Removed List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall consider it as a list of SCells to be removed. If the DRX Cycle IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall use the provided value from the gNB-CU. If the DRX configuration indicator IE is contained in the UE CONTEXT MODIFICATION REQUEST message and set to "release", the gNB-DU shall release DRX configuration. If the SL DRX Cycle list IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use the provided value from the gNB-CU for the indicated RX UE of this UE. If the SL DRX configuration indicator IE is contained in the UE CONTEXT MODIFICATION REQUEST message and set to "release", the gNB-DU shall, if supported, release SL DRX configuration for the indicated RX UE of this UE. If the SRB To Be Setup List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall act as specified in the TS 38.401, and replace any previously received value. 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 value is set to be "true", or delete the RLC entity of secondary path if the value is set to be "false". 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 SRB Mapping Info IE is contained in the SRB To Be Setup List IE, the gNB-DU shall, if supported, store the mapping information indicated in the SRB Mapping Info IE for the SRB identified by the SRB ID IE and the Uu Relay RLC channel identified by the SRB Mapping Info. The gNB-DU shall use the mapping information stored for the mapping of SRB data to Uu Relay RLC channel. If the DRB To Be Setup List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall act as specified in the TS 38.401. If the DRB Mapping Info IE is contained in the DRB To Be Setup List IE, the gNB-DU shall, if supported, store the mapping information indicated in the DRB Mapping Info IE, if present, for the DRB identified by the DRB ID IE and the Uu Relay RLC channel identified by the DRB Mapping Info. The gNB-DU shall use the mapping information stored for the mapping of DRB data to Uu Relay RLC channel. If the BH Information IE is included in the UL UP TNL Information to be setup List IE or the Additional PDCP Duplication TNL 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 MODIFICATION 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 following the behaviour described for the UE Context Setup procedure. If the BH RLC Channel To Be Modified List IE is included in the UE CONTEXT MODIFICATION 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 Modified Item IEs IE for a BH RLC Channel, the gNB-DU shall, if supported, process the Traffic Mapping Information IE following the behaviour described for the UE Context Setup procedure. If the BH RLC Channel To Be Released List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall release the BH RLC channels in the list. If two UL UP TNL Information IEs are included in UE CONTEXT MODIFICATION REQUEST message for a DRB, the gNB-DU shall include two DL UP TNL Information IEs in UE CONTEXT MODIFICATION 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 MODIFICATION 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 MODIFICATION 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 MODIFICATION REQUEST message for a DRB, the 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 MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account for the DRB with more than two RLC entities. If DC Based Duplication Configured IE is included in the UE CONTEXT MODIFICATION REQUEST message for a DRB, the 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. Otherwise, the gNB-DU shall regard that DC based PDCP duplication is de-configured for this DRB id the value is set to be "false", and it should stop PDCP duplication activation/deactivation by MAC CE. If DC Based Duplication Activation IE is included in the UE CONTEXT MODIFICATION REQUEST message for a DRB, the 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 MODIFICATION 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. For a certain DRB which was allocated with two GTP-U tunnels, if such DRB is modified and given one GTP-U tunnel via the UE Context Modification procedure, the gNB-DU shall consider that the CA based PDCP duplication for the concerned DRB is de-configured. If such UE Context Modification procedure occurs, the Duplication Activation IE shall not be included for the concerned DRB. If the UL Configuration IE in DRB to Be Setup Item IE or DRB to Be Modified Item IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall take it into account for UL scheduling. If the RRC Reconfiguration Complete Indicator IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall consider the ongoing reconfiguration procedure involving changes of the L1/L2 configuration at the gNB-DU signalled to the gNB-CU via the CellGroupConfig IE for MR-DC operation or standalone operation has been successfully performed when such IE is set to 'true'; otherwise (when such IE is set to 'failure'), the gNB-DU shall consider the ongoing reconfiguration procedure has been failed and it shall continue to use the old L1/L2 configuration. If DL PDCP SN length IE is included in the UE CONTEXT MODIFICATION REQUEST message for a DRB, gNB-DU shall, if supported, store this information and use it for lower layer configuration. If UL PDCP SN length IE is included in the UE CONTEXT MODIFICATION REQUEST message for a DRB, gNB-DU shall, if supported, store this information and use it for lower layer configuration. If the RLC Failure Indication IE is included in UE CONTEXT MODIFICATION REQUEST message, the gNB-DU should consider that the RLC entity indicated by such IE needs to be re-established when the CA-based packet duplication is active, and the gNB-DU may include the Associated SCell List IE in UE CONTEXT MODIFICATION RESPONSE by containing a list of SCell(s) associated with the RLC entity indicated by the RLC Failure Indication IE. If the UE CONTEXT MODIFICATION REQUEST message contains the RRC-Container IE, the gNB-DU shall send the corresponding RRC message to the UE. If the UE CONTEXT MODIFICATION REQUEST message includes the Execute Duplication IE, the gNB-DU shall perform CA based duplication, if configured, for the SRB for the included RRC-Container IE. If the UE CONTEXT MODIFICATION REQUEST message contains the Transmission Action Indicator IE, the gNB-DU shall stop or restart (if already stopped) data transmission for the UE, according to the value of this IE. It is up to gNB-DU implementation when to stop or restart the UE scheduling. For EN-DC operation, if the DRB to Be Setup List IE is present in the UE CONTEXT MODIFICATION REQUEST message the gNB-CU shall include 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 the DRB Information IE in the UE CONTEXT MODIFICATION REQUEST message. 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 MODIFICATION 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 MODIFICATION RESPONSE message. If the MeasConfig IE is included in the CU to DU RRC Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall deduce that changes to the measurements' configuration need to be applied. The gNB-DU shall take the received info, e.g. the measObjectToAddModList IE, and/or the measObjectToRemoveList IE into account, when generating measurement gap and when deciding if a measurement gap is needed or not. If the NeedForGapsInfoNR IE is included in the CU to DU RRC Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it as described in TS 38.331. If the NeedForGapNCSG-InfoNR IE is included in the CU to DU RRC Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it as described in TS 38.331. If the NeedForGapNCSG-InfoEUTRA IE is included in the CU to DU RRC Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it as described in TS 38.331. For DC operation, if the gNB-CU includes the CG-Config IE in the CU to DU RRC Information IE that is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU may initiate low layer parameters coordination taking this information into account. 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 MODIFICATION REQUEST message, the gNB-DU shall regard it as an indication of V2X sidelink information as defined in TS 38.331. For EN-DC operation, if the gNB-CU includes the Resource Coordination Transfer Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it for the purpose of resource coordination. If the gNB-CU received the MeNB Resource Coordination Information as defined in TS 36.423, after completion of UE Context Setup procedures, the gNB-CU shall transparently transfer it to the gNB-DU via the Resource Coordination Transfer Container IE in the UE CONTEXT MODIFICATION 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. If the Ignore PRACH Configuration IE is present and set to "true" the E-UTRA PRACH Configuration IE in the UE CONTEXT MODIFICATION REQUEST message shall be ignored. For NGEN-DC or NE-DC operation, if the gNB-CU includes the Resource Coordination Transfer Information IE in the UE CONTEXT MODIFICATION 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, after completion of UE Context Setup procedures, the gNB-CU shall transparently transfer it to the gNB-DU via the Resource Coordination Transfer Container IE in the UE CONTEXT MODIFICATION 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. For EN-DC operation, and if the Subscriber Profile ID for RAT/Frequency priority IE is received from an MeNB, the UE CONTEXT MODIFICTION 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 MODIFICATION 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 modified at the gNB-CU, the Index to RAT/Frequency Selection Priority IE shall be included in the UE CONTEXT MODIFICATION REQUEST. The gNB-DU may use it for RRM purposes. Only one of the Uplink TxDirectCurrentList Information IE and Uplink TxDirectCurrentTwoCarrierList Information IE may be contained in the UE CONTEXT MODIFICATION REQUEST message. If the UE CONTEXT MODIFICATION REQUEST message contains one of the Uplink TxDirectCurrentList Information IE or the Uplink TxDirectCurrentTwoCarrierList Information IE, the gNB-DU may take that into account when selecting L1 configuration. The UEAssistanceInformation IE shall be included in CU to DU RRC Information IE in the UE CONTEXT MODIFICATION 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 MODIFICATION 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 MODIFICATION 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 MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account when configuring LTE sidelink resources for the UE. The gNB-DU shall report to the gNB-CU, in the UE CONTEXT MODIFICATION RESPONSE message, the result for all the requested or modified DRBs, SRBs, BH RLC Channels, Uu Relay RLC channels, PC5 Relay RLC channels, and SL DRBs 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 be Setup 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 be Modified List IE;
• A list of SRBs which failed to be established shall be included in the SRB Failed to be 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 successfully modified SRBs with logical channel identities for primary path shall be included in the SRB Modified 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 BH RLC channels which are successfully modified shall be included in the BH RLC Channel Modified List IE;
• A list of BH RLC channels which failed to be modified shall be included in the BH RLC Channel Failed to be Modified List IE;
• A list of Uu Relay RLC channels which are successfully established shall be included in the Uu RLC Channel Setup List IE;
• A list of Uu Relay RLC channels which failed to be established shall be included in the Uu RLC Channel Failed to be Setup List IE;
• A list of Uu Relay RLC channels which are successfully modified shall be included in the Uu RLC Channel Modified List IE;
• A list of Uu Relay RLC channels which are failed to be modified shall be included in the Uu RLC Channel Failed to be Modified List IE;
• A list of PC5 Relay RLC channels which are successfully established shall be included in the PC5 RLC Channel Setup List IE;
• A list of PC5 Relay RLC channels which failed to be established shall be included in the PC5 RLC Channel Failed to be Setup List IE;
• A list of PC5 Relay RLC channels which are successfully modified shall be included in the PC5 RLC Channel Modified List IE;
• A list of PC5 Relay RLC channels which failed to be modified shall be included in the PC5 RLC Channel Failed to be Modified 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 be Setup List IE;
• A list of SL DRBs which are successfully modified shall be included in the SL DRB Modified List IE;
• A list of SL DRBs which failed to be modified shall be included in the SL DRB Failed to be Modified List IE.

For each GBR DRB, if the Alternative QoS Parameters Sets IE is included in the GBR QoS Flow Information IE in the UE CONTEXT MODIFICATION REQUEST message, gNB-DU shall, if supported, behave the same as the NG-RAN node in the PDU Session Resource Setup procedure, specified in TS 38.413. 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 BAP Control PDU Channel IE is included in the BH RLC Channel to be Modified 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. Otherwise, if the BAP Control PDU Channel IE is not present for any BH RLC channel, any available BH RLC channel can be used to transmit BAP Control PDUs as specified in TS 38.340. If the F1-C Transfer Path IE is included in UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account. When the gNB-DU reports the unsuccessful establishment of a DRB or SRB or SL DRB or a BH RLC channel or a Uu Relay RLC channel or a PC5 Relay RLC channel, the cause value should be precise enough to enable the gNB-CU to know the reason for the unsuccessful establishment. If the Resource Coordination Transfer Container IE is included in the UE CONTEXT MODIFICATION 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 DU to CU RRC Information IE is included in the UE CONTEXT MODIFICATION RESPONSE message, the gNB-CU shall perform RRC Reconfiguration as described in TS 38.331. The CellGroupConfig IE shall transparently be signaled to the UE as specified in TS 38.331. If the UE-CapabilityRAT-ContainerList IE is included in the UE CONTEXT SETUP MODIFICATION REQUEST, the gNB-DU shall take this information into account for UE specific configurations. If the SCell Failed To Setup List IE is contained in the UE CONTEXT MODIFICATION 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 C-RNTI IE is included in the UE CONTEXT MODIFICATION RESPONSE, the gNB-CU shall consider that the C-RNTI has been allocated by the gNB-DU for this UE context. If the Inactivity Monitoring Request IE is contained in the UE CONTEXT MODIFICATION 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 MODIFICATION 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. The UE Context Modify Procedure is not used to configure SRB0. If in the UE CONTEXT MODIFICATION REQUEST, the Notification Control IE is included in the DRB to Be Setup List IE or the DRB to Be Modified List IE 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 containded in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall replace the received UL PDU Session Aggregate Maximum Bit Rate and use it as specified in TS 23.501. If the gNB-DU UE Aggregate Maximum Bit Rate Uplink IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall:

• replace the previously provided gNB-DU UE Aggregate Maximum Bit Rate Uplink with the new received gNB-DU UE Aggregate Maximum Bit Rate Uplink;
• use the received gNB-DU UE Aggregate Maximum Bit Rate Uplink for non-GBR Bearers for the concerned UE.

The gNB-DU UE Aggregate Maximum Bit Rate Uplink IE shall be sent in the UE CONTEXT MODIFICATION REQUEST if DRB to Be Setup List IE is included and the gNB-CU has not previously sent it. The gNB-DU shall store and use the received gNB-DU UE Aggregate Maximum Bit Rate Uplink IE. If the RLC Status IE is included in the UE CONTEXT MODIFICATION RESPONSE message, the gNB-CU shall assume that RLC has been reestablished at the gNB-DU and may trigger PDCP data recovery. If the GNB-DU Configuration Query IE is contained in the UE CONTEXT MODIFICATION REQUEST message, gNB-DU shall include the DU To CU RRC Information IE in the UE CONTEXT MODIFICATION RESPONSE message. If the Bearer Type Change IE is included in DRB to Be Modified List IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall either reset the lower layers or generate a new LCID for the affected bearer as specified in TS 37.340. For NE-DC operation, if NeedforGap IE is included in the UE CONTEXT MODIFICATION REQUEST message,the gNB-DU shall generate measurement gap for the SeNB. If the QoS Flow Mapping Indication IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU 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 Lower Layer presence status change IE set to "suspend lower layers" is included in the UE CONTEXT MODIFICATION REQUEST, the gNB-DU shall keep all lower layer configuration for UEs, and not transmit or receive data from UE. If the Lower Layer presence status change IE set to "resume lower layers" is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall use the previously stored lower layer configuration for the UE. If the Full Configuration IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall generate a CellGroupConfig IE using full configuration and include it in the UE CONTEXT MODIFICATION RESPONSE. If the Full Configuration IE is contained in the UE CONTEXT MODIFICATION RESPONSE message, the gNB-CU shall consider that the gNB-DU has generated the CellGroupConfig IE using full configuration. 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 UE CONTEXT MODIFICATION 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 NR V2X Services Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, update its V2X services authorization information for the UE accordingly. If the NR V2X Services Authorized IE includes one or more IEs set to "not authorized", the gNB-DU shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant service(s). If the LTE V2X Services Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, update its V2X services authorization information for the UE accordingly. If the LTE V2X Services Authorized IE includes one or more IEs set to "not authorized", the gNB-DU shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant service(s). If the LTE UE Sidelink Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported:

• replace the previously provided UE LTE Sidelink Aggregate Maximum Bit Rate, if available in the UE context, with the received value;
• use the received value for the concerned UE's sidelink communication in network scheduled mode for LTE V2X services.

If the NR UE Sidelink Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported:

• replace the previously provided UE NR Sidelink Aggregate Maximum Bit Rate, if available in the UE context, with the received value;
• use the received value for the concerned UE's sidelink communication in network scheduled mode for NR V2X services.

If the PC5 Link Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported:

• replace the previously provided UE PC5 Link Aggregate Bit Rate, if available in the UE context, with the received value;
• use the received value 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 MODIFICATION REQUEST message, the gNB-DU shall, if supported, take into account the corresponding information received in the TSC Traffic Characteristics IE. If the Conditional Intra-DU Mobility Information IE is included in the UE CONTEXT MODIFICATION REQUEST message and the CHO Trigger is set to "CHO-initiation", the gNB-DU shall consider that the request concerns a conditional handover or conditional PSCell addition 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 MODIFICATION RESPONSE message. The gNB-DU shall regard it as a reconfiguration with sync as defined in TS 38.331. If the Conditional Intra-DU Mobility Information IE is included in the UE CONTEXT MODIFICATION REQUEST message and the CHO Trigger is set to "CHO-replace", the gNB-DU shall replace the existing prepared conditional mobility identified by the gNB-DU UE F1AP ID IE and the SpCell ID IE. If the Conditional Intra-DU Mobility Information IE is included in the UE CONTEXT MODIFICATION REQUEST message and the CHO Trigger is set to "CHO-cancel", the gNB-DU shall consider that the gNB-CU is about to remove any reference to, and release any resources previously reserved for the candidate cells associated to the UE-associated signalling identified by the gNB-CU UE F1AP ID IE and the gNB-DU UE F1AP ID IE. If the Candidate Cells To Be Cancelled List IE is also included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall consider that only the resources reserved for the cells identified by the included NR CGIs are about to be released by the gNB-CU. If the Transmission Stop Indicator IE is included within the DRB to Be Modified Item IE in the UE CONTEXT MODIFICATION REQUEST message and set to "true", the gNB-DU shall, if supported, stop the data transmission for the DRB. It is up to gNB-DU implementation when to stop the UE scheduling for that DRB. If the SCG Indicator IE is contained in the UE CONTEXT MODIFICATION REQUEST message and it is set to "released", the gNB-DU shall, if supported, deduce that an SCG is removed. If the Estimated Arrival Probability IE is contained in the Conditional Intra-DU Mobility Information IE included in the UE CONTEXT MODIFICATION REQUEST message, then the gNB-DU may use the information to allocate necessary resources for the UE. If the Location Measurement Information IE is included in the CU to DU RRC Information IE in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account when configuring measurement gaps for the UE. If the F1-C Transfer Path NRDC IE is included in UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account. If for a given E-RAB for EN-DC operation the ENB DL Transport Layer Address IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed. If for a given Qos flow for NG-RAN operation the PDCP Terminating Node DL Transport Layer Address IE is included in the UE CONTEXT MODIFICATION REQUEST message, then the gNB-DU shall, if supported, use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed. If the gNB-DU is an IAB-DU, and if the IAB Conditional RRC Message Delivery Indication IE is included in the UE CONTEXT MODIFICATION REQUEST message together with the RRC-Container IE, and if its value is set to "true", and if the RRC-Container IE is for a child IAB-MT of the gNB-DU, the gNB-DU shall, if supported, withhold the RRC message until one of the following conditions is met: If the MDT Polluted Measurement Indicator IE is included in the UE CONTEXT MODIFICATION REQUEST, the gNB-DU shall take this information into account as specified in TS 38.401. If the SCG Activation Request IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU may use it to configure SCG resources as specified in TS 37.340 , and if supported, shall include the SCG Activation Status IE in the UE CONTEXT MODIFICATION RESPONSE message. If the CG-SDT Query Indication IE is included in the UE CONTEXT MODIFICATION REQUEST message and set to 'true', the gNB-DU shall, if supported, provide the CG-SDT related resource configuration for the bearers indicated as SDT bearers in the SDT-MAC-PHY-CG-Config IE within the DU to CU RRC Information IE contained in the UE CONTEXT MODIFICATION RESPONSE message to the gNB-CU. If the SDT-MAC-PHY-CG-Config IE is also included in the UE CONTEXT MODIFICATION REQUEST message within the CU to DU RRC Information IE, the gNB-DU may provide the delta signalling version of the SDT-MAC-PHY-CG-Config IE within the DU to CU RRC Information IE contained in the UE CONTEXT MODIFICATION RESPONSE message to the gNB-CU. If the SDT Bearer Configuration Query Indication IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, provide the RLC bearer configuration in the SDT Bearer Configuration Info IE in the UE CONTEXT MODIFICATION RESPONSE message for each bearer indicated as SDT bearer. If the 5G ProSe Authorized IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, update its 5G ProSe services authorization information for the UE accordingly. If the 5G ProSe Authorized IE includes one or more IEs set to "not authorized", the gNB-DU shall, if supported, initiate actions to ensure that the UE is no longer accessing the relevant service(s). If the 5G ProSe UE PC5 Aggregate Maximum Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported:

• replace the previously provided 5G ProSe UE PC5 Aggregate Maximum Bit Rate, if available in the UE context, with the received value;
• use the received value for the concerned UE's sidelink communication in network scheduled mode for 5G ProSe services.

If the 5G ProSe PC5 Link Aggregate Bit Rate IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported:

• replace the previously provided 5G ProSe PC5 Link Aggregate Bit Rate, if available in the UE context, with the received value;
• use the received value for the concerned UE's sidelink communication in network scheduled mode for 5G ProSe services as defined in TS 23.304.

If the Updated Remote UE Local ID IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, replace the previously provided Remote UE Local ID, if available in the UE context, with the received value. If the Uu RLC Channel To Be Setup List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, act as specified in TS 38.401. If the Uu RLC Channel To Be Modified List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, act as specified in TS 38.401. If the Uu RLC Channel To Be Release List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, release the Uu Relay RLC channels in the list. If the PC5 RLC Channel To Be Setup List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, act as specified in TS 38.401. gNB-DU generates the PC5 Relay RLC channel configurations for a L2 U2N Remote UE or U2N Relay UE. If the F1AP-IDs are associated with a U2N Relay UE, the PC5 RLC Channel to be Setup Item IEs IE shall include the Remote UE Local ID and correspondingly, the PC5 RLC Channel Setup Item IEs IE and the PC5 RLC Channel Failed to be Setup Item IE in the UE CONTEXT MODIFICATION RESPONSE message shall include the Remote UE Local ID IE. If the PC5 RLC Channel To Be Modified List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, act as specified in TS 38.401. gNB-DU generates the PC5 Relay RLC channel configurations for a L2 U2N Remote UE or U2N Relay UE. If the F1AP-IDs are associated with a U2N Relay UE, the PC5 RLC Channel to be Modified Item IEs IE shall include the Remote UE Local ID IE and correspondingly, the PC5 RLC Channel Modified Item IEs IE and the PC5 RLC Channel Failed to be Modified Item IEs IE in the UE CONTEXT MODIFICATION RESPONSE message shall include the Remote UE Local ID IE. If the PC5 RLC Channel To Be Release List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, release the PC5 Relay RLC channels in the list. If the F1AP-IDs are associated with a U2N Relay UE, the PC5 RLC Channel to be Released Item IEs IE shall include the Remote UE Local ID IE. If the Path Switch Configuration IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, use it to configure the path switch from direct path to indirect path as specified in TS 38.401. If the MUSIM-GapConfig IE is contained in the CU to DU RRC Information IE included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, decide to use this IE for MUSIM gap configuration or select another one based on the received UEAssistanceInformation IE. If gNB-DU selects a different MUSIM gap configuration from received UEAssistanceInformation IE, then it shall include the selected MUSIM gap information to the gNB-CU in the MUSIM-GapConfig IE of the DU to CU RRC Information IE that is included in the UE CONTEXT MODIFICATION RESPONSE message. If MUSIM-GapConfig IE is not contained in the CU to DU RRC Information IE, then gNB-DU shall, if supported, send the selected MUSIM gap configuration based on the received UEAssistanceInformation IE, to the gNB-CU in the MUSIM-GapConfig IE of the DU to CU RRC Information IE that is included in the UE CONTEXT MODIFICATION RESPONSE message. When MUSIM-GapConfig IE is received, the gNB-CU should use this value. If the gNB-DU UE Slice Maximum Bit Rate List IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported,

• store and replace the previously provided gNB-DU UE Slice Maximum Bit Rate List, if any, with the new received gNB-DU UE Slice Maximum Bit Rate List;
• use the received gNB-DU UE Slice Maximum Bit Rate List for the uplink traffic policing for each concerned slice as specified in TS 23.501.

If the Multicast MBS Session Setup List IE or the Multicast MBS Session Remove List IE or both IEs are contained in the UE CONTEXT MODIFICATION REQUEST message the gNB-DU shall, if supported, store and use the information for configuring MBS Session Resources, if applicable. If the UE Multicast MRB To Be Setup at Modify List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall, if supported, take it into account for configuring MBS Session Resources, if applicable, and shall include the Multicast F1-U Context Reference CU IE, if available, in the UE CONTEXT MODIFICATION RESPONSE message. And if the MBS PTP Retransmission Tunnel Required IE is included in the UE Multicast MRB to Be Setup at Modify Item IEs IE, the gNB-DU shall, if supported trigger the establishment of the MBS PTP Retransmission F1-U tunnel. If the MBS PTP Forwarding Tunnel Required Information IE is included in the UE Multicast MRB to Be Setup at Modify Item IEs IE, the gNB-DU shall, if supported trigger the establishment of the MBS PTP Forwarding F1-U tunnel. If the Management Based MDT PLMN Modification List IE is contained in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU 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. If the InterFrequencyConfig-NoGap IE is included in the DU to CU RRC Information IE contained in the UE CONTEXT MODIFICATION RESPONSE message, the gNB-CU shall, if supported, use it as described in TS 38.331. If the ul-GapFR2-Config IE is contained in the DU to CU RRC Information IE that is included in the UE CONTEXT MODIFICATION RESPONSE message, the gNB-CU shall, if supported, use it as described in TS 38.331.

In case none of the requested modifications of the UE context can be successfully performed, the gNB-DU shall respond with the UE CONTEXT MODIFICATION FAILURE message with an appropriate cause value. If the Conditional Intra-DU Mobility Information IE was included in the UE CONTEXT MODIFICATION REQUEST message and set to "CHO-initiation", the gNB-DU shall include the received SpCell ID IE as the Requested Target Cell ID IE in the UE CONTEXT MODIFICATION FAILURE message. If the gNB-DU is not able to accept the SpCell ID IE in UE CONTEXT MODIFICATION REQUEST message, it shall reply with the UE CONTEXT MODIFICATION FAILURE message. If the Conditional Intra-DU Mobility Information IE was included and set to "CHO-initiation" or "CHO-replace" but the SpCell ID IE was not included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall respond with the UE CONTEXT MODIFICATION FAILURE message with an appropriate cause value.

If the gNB-DU receives a UE CONTEXT MODIFICATION 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 MODIFICATION RESPONSE message with an appropriate cause value. If the gNB-DU receives a UE CONTEXT MODIFICATION 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 MODIFICATION 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 MODIFICATION 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 MODIFICATION RESPONSE message with an appropriate cause value. If one or more candidate cells in the Candidate Cells To Be Cancelled List IE included in the UE CONTEXT MODIFICATION REQUEST message were not prepared using the same UE-associated signaling connection, the gNB-DU shall ignore those non-associated candidate cells. 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 MODIFICATION REQUEST message was not prepared using the same UE-associated signalling connection, the gNB-DU shall ignore this candidate cell. If more than one of the following IEs, i.e., the Uplink TxDirectCurrentList Information IE and the Uplink TxDirectCurrentTwoCarrierList Information IE is included in the UE CONTEXT MODIFICATION REQUEST message, the gNB-DU shall consider it as a logical error.