5G-SP821 DC DL Aggregation_Partial Feature Summary

5G-SP821DCDLAggregationPartialFeatureSummary,PresentationofSP821forinternaluseMaybeuseasabaseforfeaturedescriptionordeepdive,e.g.forNSA,2018-09-13,Downlink(DL)DualConnectivity(DC)userplanedataissentonbothlegsaccordingtoaggregationalgorithmandFlowControl(FC)feedbackreceivedinreversedirection.FCfeedbackisreceivedoverX2-UfortheLTEleg(Seesupportslideforinterfaceexplanations)FCfeedbackissentviainternalgNBsignalingmessagesforthelocalNRleg,DLDCAggregationSummary1(2),PDCP,NR,LTE,ThegNBshallActivateFConthelocalNRlegwhentheRLCSDUageexceedsathreshold.StartDLDCAggregationwhenNRLegqualityisgoodenoughandPDCPSDUageexceedsathresholdvalue.StartofDLDCAggregationiscontrolledbyanoperatorparameter.StopDLDCAggregationwhenPDUbufferhasbeenemptyforapredefinedtime,atRadioLinkFailure(RLF)orwhenNRDLradioqualitybecomespoor.WhenDLDCAggregationisstoppedduetopoorNRradioqualityflushdatainbothLTEandNRRLCbuffersandretransmitnon-acknowledgedpacketsintheLTEleg(inorder).Observability:Countersmeasuringthevolumeandnumberofpacketsofsentoneachlegwhilethebearerhasaggregationactivated.Characteristicsrequirement:Aggregatedfullbufferdatarateforsingleuserinlowloadedandgoodradioconditions:Atleast75%of(maxLTErate+maxNRrate),DLDCAggregationSummary2(2),ThemodifiedFCfunctionalityintroducedbythisSPconsistsoftwoco-operatingparts:TheSlowPathScheduler(SPS)andtheBearerSplitScheduler(BSS)algorithm:SPSschedulerTheSPSalgorithmisusedbytheFCfunctiontodecideasuitableratefordatatobesentfromthePPFtooneoftheconnectedlegs,andthisisdoneatregularintervalscalledtheSPSinterval.TheoutputoftheSPSalgorithmistheFCratetobeusedforthelegforthefollowingSPSinterval(10msdefault).BSSschedulerBasedontheoutputfromtheSPSscheduler,theBSSschedulercalculatesabitrateforrateshapingperlegateachSPSintervalexpiry.Therateshapingisthenenforcedusingatokenbucketalgorithmandatveryshortintervals(0.1ms)theSPSentitywillperformschedulingbasedonavailabletokens.Formoredetails,seeSP821NDS.,AggregationAlgorithmOverview,gNBPP:E6impact,systemconstantsgNBL2:newfunctionalityinPDCPmaster,PDCPproxyandRLCtohandleFCandDCaggregationExternal/internalinterfaces:E6:supporttosignalnewparametervalueforDCAggregation.NR-UEMI:supporttosignalnewparametersforFCandDCAggregation,ImpactedAreas,NosupportforimprovedFCfeedbackprovidinginformationabout“highesttransmittedPDCPsequencenumber”(periodicreporting)OnlyFCfeedbackbasedonhighestdeliveredSNsupportedNosupportforremoteNRlegPDCPandNRRLCalwaysinsamegNBAQMminratediscardstillonlyonRLClevel(inbothLTEandNRLeg)ULaggregationandULLegswitchingisnotsupported,Limitations,Thefeatureislicensecontrolled:,Licensecontrol,DLTransmissionStatesDRB,SinglelegLTE(gNbPDCP),SinglelegNR(gNbPDCP),AggregationLTE+NR(gNbPDCP),SplitbearerconfigwithNRLegSetup(GoodNRquality),PoorNRquality,GoodNRqualityANDLegswitchprohibittimerexpiry,NRRLF,PDCPSDUbufferagedcDlAggActTime,AllDLpacketssentandacknowledgedplusguardperiodexpired,TransitionsandcriteriaintroducedbyearlierSPs,TransitionsandcriteriaintroducedbythisSP,LTE(eNBPDCP),NRRLF,NRRLF,PoorNRquality,Inpre-SP821functionality(SP443&SP666)incomingpacketsareforwardeddirectlytotheNRRLCSDUbufferSP821addsFCfortheNRlegwhichisenabledinPDCPMasterwhenT_Ack-T_transmissiondlPdcpSpsTargetTimeNR(ms)T_transmission:timewhenPDCPPDUissentfromPDCPMastertoNRRLCT_Ack:timewhencorrespondingackisreceivedinPDCPMaster,SingleNRlocalleg(FCdisabled),PDCPMaster,NRRLC,SgNB,DLpackets,LocalRLCSDUbuffer,RLCACK,PDCPACK,PDCPprocessing,IncomingpacketsarefirststoredinthePDCPSDUbuffer.PacketsarethensenttothelocalNRRLCSDUbufferbasedonFCfeedbackRequiredFCfeedbackinformationisprovidedviagNBinternalsignaling.PDCPSDUbufferageismonitoredtodeterminewhenDCaggregationshouldbestarted.Note:TheabovefunctionalityfortheremoteLTEleghasalreadybeenintroducedinSPs443&666,SingleNRlocalleg(FCenabled),PDCPMaster,NRRLC,SgNB,DLpackets,LocalRLCSDUbuffer,RLCACK,PDCPACK,PDCPprocessing,PDCPSDUbuffer,Criteriatostartaggregation:NRLegisusedFCisenabledontheNRLegPDCPSDUbufferagedcDlAggActTime(ms)Criteriatostopaggregation:NRLegisusedFCisenabledontheNRLegPDCPSDUbufferagedcDlAggExpiryTimer(ms),TriggerConditions:“SingleNRLeg”to“Aggregation”and“Aggregation”to“SingleLeg”,PDCPMaster,NRRLC,SgNB,DLpackets,LocalRLCSDUbuffer,RLCACK,PDCPACK,PDCPprocessing,PDCPSDUbuffer,FlowControl(FC)isactiveonbothlegsDLdataisscheduledonbothlegsaccordingtofeedbackinformationandtheSPSandBSSschedulingalgorithms.Acopyiskeptofnon-acknowledgedpacketsinPDCPPDUbuffer(notshowninthepicture),Actionsinaggregation,PDCPMaster,NRRLC,SgNB,DLpackets,RLCSDUbuffer,RLCACK,PDCPACK,PDCPprocessing,PDCPSDUbuffer,MeNB,LTERLC,RLCSDUbuffer,RLCACK,PDCPACK,X2-U,5G-SP821Administration,Theseattributesmaybesetbytheoperator.dlPdcpSpsTargetTimeNR&dlPdcpSpsTargetTimeLTEControlstheamountofdataavailableintheDUbuffers.dcDlAggActTimeControlswhenaggregationisactivated.dcDlAggExpiryTimerControlsthedeactivationofaggregation.,EN-DCinterfacesforNSADualleg&Aggregation,LogicalNetworkFunctions:RCFRadioControllerFunctionCorrespondsto3GPPlogicalentityCU-CPinagNBPPFPacketProcessingFunctionCorrespondsto3GPPlogicalentityCU-UPinagNBRPFRadioProcessingFunctionCorrespondsto3GPPlogicalentityDUinagNB,NRL1&L2,LTERRC(NRRRC),S1-C,Userplane,RCF,PPF,RPF,S1-U,RCF,PPF&RPF,LTEL1&L2,CU-CPCentralizedUnitControlPlaneCU-UPCentralizedUnitUserPlaneDUDistributedUnit,PDCP,NRRLC,NRMACMAC,NRPHY,LTEPDCP,LTERLC,LTEMAC,LTEPHY,RRC,ND