The purpose of this procedure is to modify an RRC connection, e.g. to establish/modify/release RBs/BH RLC channels/Uu Relay RLC channels/PC5 Relay RLC channels, to perform reconfiguration with sync, to setup/modify/release measurements, to add/modify/release SCells and cell groups, to add/modify/release conditional handover configuration, to add/modify/release conditional PSCell change or conditional PSCell addition configuration. As part of the procedure, NAS dedicated information may be transferred from the Network to the UE.
RRC reconfiguration to perform reconfiguration with sync includes, but is not limited to, the following cases:
reconfiguration with sync and security key refresh, involving RA to the PCell/PSCell, MAC reset, refresh of security and re-establishment of RLC and PDCP triggered by explicit L2 indicators;
reconfiguration with sync but without security key refresh, involving RA to the PCell/PSCell, MAC reset and RLC re-establishment and PDCP data recovery (for AM DRB or AM MRB) triggered by explicit L2 indicators.
reconfiguration with sync for DAPS and security key refresh, involving RA to the target PCell, establishment of target MAC, and
for non-DAPS bearer: refresh of security and re-establishment of RLC and PDCP triggered by explicit L2 indicators;
for DAPS bearer: establishment of RLC for the target PCell, refresh of security and reconfiguration of PDCP to add the ciphering function, the integrity protection function and ROHC function of the target PCell;
for SRB: refresh of security and establishment of RLC and PDCP for the target PCell;
reconfiguration with sync for DAPS but without security key refresh, involving RA to the target PCell, establishment of target MAC, and
for non-DAPS bearer: RLC re-establishment and PDCP data recovery (for AM DRB or AM MRB) triggered by explicit L2 indicators.
for DAPS bearer: establishment of RLC for target PCell, reconfiguration of PDCP to add the ciphering function, the integrity protection function and ROHC function of the target PCell;
for SRB: establishment of RLC and PDCP for the target PCell.
reconfiguration with sync for direct-to-indirect path switch, not involving RA at target side, involving re-establishment of PDCP /PDCP data recovery (for AM DRB) triggered by explicit L2 indicators.
In (NG)EN-DC and NR-DC, SRB3 can be used for measurement configuration and reporting, for UE assistance (re-)configuration and reporting for power savings, for IP address (re-)configuration and reporting for IAB-nodes, to (re-)configure MAC, RLC, BAP, physical layer and RLF timers and constants of the SCG configuration, and to reconfigure PDCP for DRBs associated with the S-KgNB or SRB3, and to reconfigure SDAP for DRBs associated with S-KgNB in NGEN-DC and NR-DC, and to add/modify/release conditional PSCell change configuration, provided that the (re-)configuration does not require any MN involvement, and to transmit RRC messages between the MN and the UE during fast MCG link recovery. In (NG)EN-DC and NR-DC, only measConfig, radioBearerConfig, conditionalReconfiguration, bap-Config, iab-IP-AddressConfigurationList, otherConfig and/or secondaryCellGroup are included in RRCReconfiguration received via SRB3, except when RRCReconfiguration is received within DLInformationTransferMRDC.
The Network may initiate the RRC reconfiguration procedure to a UE in RRC_CONNECTED. The Network applies the procedure as follows:
the establishment of RBs (other than SRB1, that is established during RRC connection establishment) is performed only when AS security has been activated;
the establishment of BH RLC Channels for IAB is performed only when AS security has been activated;
the establishment of Uu Relay RLC channels and PC5 Relay RLC channels (other than SL-RLC0 and SL-RLC1) for L2 U2N Relay UE is performed only when AS security has been activated, and the establishment of PC5 Relay RLC channels for L2 U2N Remote UE (other than SL-RLC0 and SL-RLC1) is performed only when AS security has been activated;
the addition of Secondary Cell Group and SCells is performed only when AS security has been activated;
the reconfigurationWithSync is included in secondaryCellGroup only when at least one RLC bearer or BH RLC channel is setup in SCG;
the reconfigurationWithSync is included in masterCellGroup only when AS security has been activated, and SRB2 with at least one DRB or multicast MRB or, for IAB, SRB2, are setup and not suspended;
the conditionalReconfiguration for CPC is included only when at least one RLC bearer is setup in SCG;
the conditionalReconfiguration for CHO or CPA is included only when AS security has been activated, and SRB2 with at least one DRB or multicast MRB or, for IAB, SRB2, are setup and not suspended.
The UE shall perform the following actions upon reception of the RRCReconfiguration, or upon execution of the conditional reconfiguration (CHO, CPA or CPC):
if the RRCReconfiguration is applied due to a conditional reconfiguration execution upon cell selection performed while timer T311 was running, as defined in clause 5.3.7.3:
re-use the source RAT SDAP and PDCP configurations if available (i.e., current SDAP/PDCP configurations for all RBs from source E-UTRA RAT prior to the reception of the inter-RAT HO RRCReconfiguration message);
perform the RRC connection reconfiguration as specified in TS 36.331, clause 5.3.5.3 for the RRCConnectionReconfiguration message included in eutra-SCG;
include in the uplinkTxDirectCurrentTwoCarrierList the list of uplink Tx DC locations for the configured intra-band uplink carrier aggregation in the MCG;
include in the uplinkTxDirectCurrentMoreCarrierList the list of uplink Tx DC locations for the configured intra-band uplink carrier aggregation in the MCG;
include in the uplinkTxDirectCurrentTwoCarrierList the list of uplink Tx DC locations for the configured intra-band uplink carrier aggregation in the SCG;
include in the uplinkTxDirectCurrentMoreCarrierList the list of uplink Tx DC locations for the configured intra-band uplink carrier aggregation in the SCG;
if the RRCReconfiguration message is applied due to conditional reconfiguration execution and the RRCReconfiguration message does not include the reconfigurationWithSync in the masterCellGroup:
if the UE has connection establishment failure or connection resume failure information available in VarConnEstFailReport or VarConnEstFailReportList and if the RPLMN is equal to plmn-Identity stored in VarConnEstFailReport or in at least one of the entries of VarConnEstFailReportList:
if the UE has radio link failure or handover failure information available in VarRLF-Report and if the RPLMN is included in plmn-IdentityList stored in VarRLF-Report; or
if the UE has radio link failure or handover failure information available in VarRLF-Report of TS 36.331 and if the UE is capable of cross-RAT RLF reporting and if the RPLMN is included in plmn-IdentityList stored in VarRLF-Report of TS 36.331:
if the applied RRCReconfiguration is not due to a conditional reconfiguration execution upon cell selection performed while timer T311 was running, as defined in clause 5.3.7.3:
perform the actions for the successful handover report determination as specified in clause 5.7.10.6, upon successfully completing the Random Access procedure triggered for the reconfigurationWithSync in spCellConfig of the MCG;
if the UE has successful handover information available in VarSuccessHO-Report and if the RPLMN is included in plmn-IdentityList stored in VarSuccessHO-Report:
if the RRCReconfiguration message was received via SRB1, but not within mrdc-SecondaryCellGroup or E-UTRA RRCConnectionReconfiguration or E-UTRA RRCConnectionResume:
for each supported NR band that is also included in requestedTargetBandFilterNR, include an entry in interFreq-needForGap and set the gap requirement information for that band;
for each supported NR band included in requestedTargetBandFilterNCSG-NR, include an entry in interFreq-needForNCSG and set the NCSG requirement information for that band;
if requestedTargetBandFilterNCSG-EUTRA is configured, for each supported E-UTRA band included in requestedTargetBandFilterNCSG-EUTRA, include an entry in needForNCSG-EUTRA and set the NCSG requirement information for that band; otherwise, include an entry for each supported E-UTRA band in needForNCSG-EUTRA and set the corresponding NCSG requirement information;
if the RRCReconfiguration message was received via E-UTRA RRC message RRCConnectionReconfiguration within MobilityFromNRCommand (handover from NR standalone to (NG)EN-DC);
if the RRCReconfiguration is applied due to a conditional reconfiguration execution for CPC which is configured via conditionalReconfiguration contained in nr-SecondaryCellGroupConfig specified in TS 36.331:
submit the RRCReconfigurationComplete message via the E-UTRA MCG embedded in E-UTRA RRC message ULInformationTransferMRDC as specified in TS 36.331, clause 5.6.2a.
submit the RRCReconfigurationComplete message via E-UTRA embedded in E-UTRA RRC message RRCConnectionResumeComplete as specified in TS 36.331, clause 5.3.3.4a;
submit the RRCReconfigurationComplete via E-UTRA embedded in E-UTRA RRC message RRCConnectionReconfigurationComplete as specified in TS 36.331, clause 5.3.5.3 / 5.3.5.4 / 5.4.2.3;
if the scg-State is not included in the E-UTRA message (RRCConnectionReconfiguration or RRCConnectionResume) containing the RRCReconfiguration message:
if bfd-and-RLM was not configured to true before the reception of the E-UTRA RRCConnectionReconfiguration or RRCConnectionResume message containing the RRCReconfiguration message or if lower layers indicate that a Random Access procedure is needed for SCG activation:
if the RRCReconfiguration message was received within nr-SecondaryCellGroupConfig in RRCConnectionReconfiguration message received via SRB3 within DLInformationTransferMRDC:
submit the RRCReconfigurationComplete via E-UTRA embedded in E-UTRA RRC message RRCConnectionReconfigurationComplete as specified in TS 36.331, clause 5.3.5.3 / 5.3.5.4;
else if the RRCReconfiguration message was received via SRB1 within the nr-SCG within mrdc-SecondaryCellGroup (UE in NR-DC, mrdc-SecondaryCellGroup was received in RRCReconfiguration or RRCResume via SRB1):
if the RRCReconfiguration is applied due to a conditional reconfiguration execution for CPC which is configured via conditionalReconfiguration contained in nr-SCG within mrdc-SecondaryCellGroup:
if bfd-and-RLM was not configured to true before the reception of the RRCReconfiguration or RRCResume message containing the RRCReconfiguration message; or
if reconfigurationWithSync was included in spCellConfig of an MCG or SCG and when MAC of an NR cell group successfully completes a Random Access procedure triggered above; or,
if sl-PathSwitchConfig was included in reconfigurationWithSync included in spCellConfig of an MCG, and when successfully sending RRCReconfigurationComplete message (i.e., PC5 RLC acknowledgement is received from target L2 U2N Relay UE):
apply the parts of the CSI reporting configuration, the scheduling request configuration and the sounding RS configuration that do not require the UE to know the SFN of the respective target SpCell, if any;
apply the parts of the measurement and the radio resource configuration that require the UE to know the SFN of the respective target SpCell (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, sounding RS configuration), if any, upon acquiring the SFN of that target SpCell;
if the active downlink BWP, which is indicated by the firstActiveDownlinkBWP-Id for the target SpCell of the MCG, has a common search space configured by searchSpaceSIB1:
for each measId of the MCG measConfig, if configured, and for each measId of the SCG measConfig, if configured, if the associated reportConfig has a reportType set to condTriggerConfig:
if the UE initiated transmission of a UEAssistanceInformation message for the corresponding cell group during the last 1 second, and the UE is still configured to provide the concerned UE assistance information for the corresponding cell group; or
if the RRCReconfiguration message is applied due to a conditional reconfiguration execution, and the UE is configured to provide UE assistance information for the corresponding cell group, and the UE has initiated transmission of a UEAssistanceInformation message for the corresponding cell group since it was configured to do so in accordance with clause 5.7.4.2:
initiate transmission of a UEAssistanceInformation message for the corresponding cell group in accordance with clause 5.7.4.3 to provide the concerned UE assistance information;
start or restart the prohibit timer (if exists) or the leave without response timer for the MUSIM associated with the concerned UE assistance information with the timer value set to the value in corresponding configuration;
if SIB12 is provided by the target PCell, and the UE initiated transmission of a SidelinkUEInformationNR message indicating a change of NR sidelink communication/discovery related parameters relevant in target PCell (i.e. change of sl-RxInterestedFreqList or sl-TxResourceReqList) during the last 1 second preceding reception of the RRCReconfiguration message including reconfigurationWithSync in spCellConfig of an MCG; or
if the RRCReconfiguration message is applied due to a conditional reconfiguration execution and the UE is capable of NR sidelink communication/discovery and SIB12 is provided by the target PCell, and the UE has initiated transmission of a SidelinkUEInformationNR message since it was configured to do so in accordance with clause 5.8.3.2:
if configured with application layer measurements and if application layer measurement report container has been received from upper layers for which the successful transmission of the message or at least one segment of the message has not been confirmed by lower layers:
if the UE initiated transmission of an MBSInterestIndication message during the last 1 second preceding reception of this RRCReconfiguration message; or
if the RRCReconfiguration message is applied due to a conditional reconfiguration execution, and the UE has initiated transmission of an MBSInterestIndication message after having received this RRCReconfiguration message:
remove all the entries within the MCG VarConditionalReconfig for which the RRCReconfiguration within condRRCReconfig does not include the masterCellGroup with reconfigurationWithSync, if any;