lte test case app note
TRANSCRIPT
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Application Note
WEBSITE:www.jdsu.com/test
LTE and EPC Test
An Overview of Test Concepts and Tools for Trials
Application Note
Specic LTE Test Areas 3
Overview3
Gainingdeeperinsights4
Performancetesting5
Single-userthroughputtesting5
Cellperformanceverificationwithmulti-userthroughputtesting 6
Realisticmulti-userthroughputtesting8
Idle-to-activetransitiontimes9
Latencytesting10
KPIverificationandcalculation10
ValidatingLTEvoice12
Signalingvalidation13
VoiceQoSandQoE(MOS) 13
TestingQoSandQoEofLTEstreamingvideo14
EvaluatingLTEMIMOandfrequency-selectivescheduling 15
Testingnetworkcoverage16
TestingLTEhandover16
ValidatingLTEbackhaul18
VerifyingLTEhandsetIOT18
Validatingdeviceconfiguration18
Table o Contents
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Appendix: Outline for a Basic Phase 1 LTE Test Plan 20
Overview20
Achievabledataratesandlatency:single-userthroughputforUL/DLandTCP/UDP20
Achievabledataratesandlatency:cellthroughputandMUthroughputforUL/DLandTCP/UDP21
Achievabledataratesandlatency:latency21
Intra-LTEmobility:mobilityandhandoverperformance 21
Achievabledataratesandlatency:applicationperformance 22
Coverageandcapacityradiofeaturesefficiencyandgainassessment:linkbudget 22
Coverageandcapacityradiofeaturesefficiencyandgainassessment:scheduler22
Evaluationofantennaconfigurationoptions23
Self-configurationandself-organizingnetworkfeatures 23
Evaluationoffrequencyreuse:onedeploymentscenario23
BasicQoS:userdifferentiationbetweennon-GBRuserswithdifferentQCI24
BasicQoS:user-differentiationbetweenGBRandnon-GBRusers24
Basicapplicationperformance:webbrowsing,streaming,voicecalls,e-mail,VPN,on-linegaming25
References 26
EPSspecificationreferences 26
3GPPreferences26
NGMNreference28
ETSIreference28
Glossary 29
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Application Note: LTE and EPC TestAn Overview of Test Concepts and Tools for Trials 3
Specifc LTE Test Areas
Overview
Creatinganoverallframeworkforthetesting,evaluation,andoptimizationofLTEandSAEisalargeandcomplextopicThisdocumentprovidesastartingpointthatcoversthetopicatarelativelyhighlevel
LookingacrossthelifecycleofatechnologysuchasLTE/SAE,thetools,processes,andmeasuresmustbetailoredtosuitorganizationalprioritiesatspecifictimeswithinthelifecycle(Figure1)JDSUprovidesacost-effectivesetofsolutionsthatenablereusingassetsacrossthelifecycleThisensuresnotonlycompletecoveragebutalsothereuseofresultsandassets,leadingtoasolidreturnoninvestment(ROI)
TheexampleslistedbelowaddressdifferentaspectsoftestingatvariousstagesintherolloutofLTE/SAETheseareofferedasanoverviewofthemajorelementsoftheLTEdeploymentlifecycle
Technologyeldtrials
EvaluatethetechnologyagainstNGMNorotherindustryrequirements
Testandvalidatetechnologyimplementations
Adoptaprocessthatismoreopenthanfullyclosedbilateraleldtrials Labtesting
EvaluateeNodeBschedulingperformance
Evaluatesecurityandbillingpolicies
Evaluateserviceperformanceincontrolledenvironments
EvaluateUEperformance
EvaluateMIMOperformancegains
Fieldtrialsandvendorevaluation
Evaluateend-to-end(E2E)performance
Evaluatenetworkcoverage
Evaluatecellandnodeperformanceunderloadedconditions
Evaluateself-optimizingnetworkcapabilities EvaluateIRATcapabilitiesandperformance
PerformKPImonitoringandbenchmarking
Figure 1. A simple model of the LTE deployment lifecycle
Technology
eld trialsLab trials
Field trialsand
vendor
evaluation
Friendly
customer
trials
Commercial
launch
Optimzationand
wider
deployment
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Application Note: LTE and EPC TestAn Overview of Test Concepts and Tools for Trials 4
Friendlycustomertrials
Understandend-userQoE/QoS
Conrmhistorictroubleshootingcapabilities
TesthandsetIOT,conformanceandpre-conformance
Monitorhandsetperformance
Includetrending,statisticsandVIPreporting
Commerciallaunch
Performservice-andaccesstechnology-awaremonitoring
VerifyE2Evisibilityandtroubleshootingcapabilities
Validateandunderstandsubscriberbehavior
UnderstandoverallnetworkandIRAThandover(HO)performance Includeintegrationwithnode-loggingcapabilities
Optimizationandwiderdeploymentphase
ValidateandensureSONcapabilitiesareworking
Locateareasforexpansion
Monitorbackhaulperformanceimpactonend-userQoE
Benchmarkserviceperformancebetweenmacroandfemtoroll-out
TheremainderofthisdocumentfocusesonthefieldtrialsportionoftheprocessEachsectiondescribesthetestcasesmostoperatorswillwanttoundertakeandalsooutlinesthetoolsthatwillensureeffectiveperformanceofsuchtestsItisassumedthatnotalloperatorswillperformallstepssowillneedtomatchthetestcases(andpossiblesolutions)touniqueneeds
Gaining deeper insights
Foryears,personnelfromacrossAgilentTechnologieshavebeeninvolvedwithtechnologystandardizationandtestdevelopmentforLTEandSAESince2008,AgilenthasactivelyprovidedtoolstohelpdeveloperstakeLTE/SAEforwardtothemarketplaceInApril2009,thecompanypublishedacomprehensivebookcalledLTEandtheEvolutionto4GWireless:DesignandMeasurementChallenges(ISBN:978-0-470-68261-6)ThisresourcehasreceivedsignificantandwidespreadpositivefeedbackfromthewirelessindustryInMay2010,JDSUacquiredtheNetworkSolutionsDivisionfromAgilentWiththisacquisition,severalcontributingauthorstothisLTEbookincludingtheauthorofthisapplicationnotetransitionedfromAgilenttoJDSUThebookisjustoneexampleofhowAgilentandnowJDSUcontributetothe
overalllandscapeoftheLTEandSAEindustryAsacompaniontothebook,thisapplicationnotecontainsrelevantreferencestotheLTEbook,whichcanbestudiedseparatelyinpursuitofadeeperunderstandingofthevarioustopicsandconceptsinvolvedinLTEtesting
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Perormance testing
WithLTE,muchofthefocushasbeenonincreasingsystemperformanceinareassuchasend-userthroughput,latency,andidle-to-activetransitionsAlthoughtheseimprovementsalongwithsignificantlyimpressivesingle-userdataratesareimportantformarketingreasons,inthemselvestheyplayalimitedroleinhowrealuserswillutilizeadeployedLTEnetworkThus,measurementsareneededforbothsingle-userpeakratesandmulti-userthroughputInanalyzingmulti-userthroughputandoverallcellcapacity,itisimportanttounderstandtheimpactofacellsrealdistributionofusersaswellasthemobilityandusagepatternsofthoseusers
Single-user throughput testing
Intheory,single-userthroughputtestingisquitesimpleHowever,inrealityitcanprovetobequitetrickyAsanexample,thefirstaspectstounderstandare what to measure and how to benchmark the result
LookingatthepublicresultsoftheLTESAETrialInitiative(LSTI)ProofofConcept(PoC)group,itcanbeseenthatpeakrateswillvaryfromafewhundredkilobitspersecondatthecelledgetoover150Mbpsinverygoodradioconditions(forexample,ina20MHz2x2MIMOsystem)Inpractice,measuringthiswiderangeofratescouldbeperformedwithadedicatedhardwaretrafficgeneratorthatwillhaveguaranteedperformanceandwillproducetrafficpreciselyaccordingtoananticipatedtrafficprofileSuchaprofilecouldincludevaryingdatarates,differenttypesoftraffic,anddelaycharacteristicssuchasjitterOtheralternativesincludesoftware-basedtrafficgenerators(forexample,iperf)orsimplygeneratingthetrafficfromexistingstandardapplicationserversusedforFTPorvideostreaming
Ifasoftware-basedtrafficgeneratorisused,itisimportanttounderstandtheconditionsunderwhichitwilldeliverreliableresultsIngeneral,currentlyavailablesoftware-basedtrafficgeneratorsproduceacorrectaveragethroughput;however,theinstantaneousvariationscouldbesignificantTogenerate
highrates,dedicatedCPUresourcesmustbeconsistentlyavailabletothegeneratorShouldotherprocessesstartonthetrafficPC,andthisisoftenthecasewithcertainoperatingsystems,theremaybecomplicatedsideeffectsintheEPCortheeUTRANbecausebufferingmightoccurunexpectedlyConsequently,theremaybeagapinthegeneratedtrafficandthusnothingtotransferovertheairinterfaceforagivenTTI
Ifnotmanagedproperly,theuseofanexistingapplicationserver(forexample,anFTPserver)togeneratethetrafficcouldalsoproduceunexpectedsideeffectsForexample,anFTPservernormallyaccessesafilefromatraditionalharddiskIfmultipleuserstrytodownloadthesamefileatthesametime,therecouldbeabottleneckcausedbytheFTPserverratherthantheLTEairinterface(ingoodradioconditions)ItispossibletosetupanFTPservertomanagethisifpropercareistakenandtheappropriatedisksystemisapplied;however,oversightsassimpleasanimproperlyconfigureddiskcanskewtheoverallresults
Whenitcomestomeasuringtheperformance,oneessentialruleofthumbistounderstandthebasic
aspectsthatwillcontroltheresultsForexample,anunderstandingoftheunderlyingradiolayertransportsettingsiscrucialHARQprovidesanexample:ifHARQisnotenabled,thelinkwillactuallydeliverahigherthroughputingoodradioconditionscomparedtotimeswhenHARQisnotswitchedonOntheotherhand,reliabletransportdependsonHARQbeingswitchedonIfnot,problemssuchasasignificantamountofTCPretransmissionwillcropup,leadingtoaverypooreffectivethroughputEvenifHARQisswitchedon,theamountofHARQretransmissioncanbeconfiguredSettingthistoaverylowvaluewillincreasetheinstantaneousthroughputbutwillleadtoapooreffectivethroughputundernon-idealradioconditions
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Foradetailedunderstandingofbearerthroughput,measurementsshouldbemadeatdifferentlayersintheprotocolstackMAClayer,IPlayerandUDPorTCPlayersafterapplicableretransmissionsDuringthesemeasurements,itisimportanttounderstandandrecordtheactualsettingsthatwereconfiguredfortheMAClayerandtheTCPlayer,andifanyspecificserviceorapplicationlayersettingshavebeenapplied(forexample,iftheapplicationusingTCPhadoneormultipleTCPflows)
InsomeveryspecificcasesitmaybeusefultomeasurethehighestpossiblebitratethattheLTEairinterfacecandeliverForthismeasurement,therecommendedapproachistomeasurethelossless(forexample,zeropacket-lossthroughput)ofasustainedUDPstreamInsuchcases,thespecificMAClayersettingsshouldberecordedaswellastheUDPpacketsizeItcouldaddsubstantialvaluetoperformanRFC2544testovertheLTEconnection;thiswillstepthroughseveraldifferentpacketsizesandthroughputratestolocatethelosslessthroughputforeachrelevantpacketsize
Tounderstandwhythroughputischangingindifferentenvironmentsatdifferenttimes,thebestapproachistorecordasetofLTE-relevantparameterswhileperformingthethroughputtestTheseparametersshouldincludetheinputstotheeNodeBschedulingdecisions(forexample,CQIforalloftheranks(widebandandsub-band),thePMI,andtherankindicator)andinformationabouttheresultingeNodeBschedulingdecisions(forexample,selectedmodulationandcoding,MIMOmode,etc)Whentestinguplinkperformance,therelevantpower-controlinformationshouldalsobelogged
JDSUprovidesallofthetoolsandprocessesneededtoplan,perform,evaluateresults,andprovidereportsforsingle-andmulti-userthroughputtestingThisincludesbothtoolstogenerateE2EtrafficaswellastoolstologdatafromhandsetsandrelevantnetworkinterfacesFortestinginthefield,signalsourcesavailablefromothervendorsemulateuplinkinterferenceandloadingcausedbyusersinothercellsBecauseloadinghasasignificantimpactonthroughputratesitshouldbeincludedaspartofanyrealisticevaluationThegeneratedinterferenceshouldideallyberepresentativeofanLTEairinterfaceinbothULandDLAlthoughwhitenoisewasacceptableforUMTS,whichusesanoise-likeCDMAairinterface,itdoesnotrepresentthepowervariationsacrossfrequencyandtimethatcharacterizeLTEsOFDMandSC-FDMAmodulationschemesRapidvariationsmaytrickschedulersintomakingeitheroptimisticorpessimisticpredictionsofthechannelconditionsandsubsequentmodulationandcodingschemethatcanbereliablytransmittedJDSUtoolsprovidethemeanstoevaluatethisimpactbeforenetworksbecomeheavilyloaded
Cell performance verification with multi-user throughput testing
MeasuringtheperformanceofanLTEsysteminasingle-usercaseprovidesabasicunderstandinguponwhichamorerealisticanalysisofthemulti-usercasecanbeperformedItshouldbeunderstoodthat,inmanycases,single-userpeakthroughputperformancewillbemuchhigherthaneventheaggregatecellthroughputwithseveralusersactivelydownloadingFromindustrystudiesperformedbyLSTIandothers,DLcellthroughputisexpectedtobearound35-40Mbps(assuming20MHzwith2x2MIMO)with10usersspreadoverthecell,allwithfullbufferdownloadsandaproportionalfairscheduler 1,2
1eseexpectationsarerelativelyconsistentwithprevious3GPPsimulations2etermfullbuerreferstotheideathattheeNodeBisconstantlyschedulingdatafromtheS1interfaceebuermustalwayscontain
enoughdatatofullysaturatethelinkeveninthecaseofaperfectRFenvironmentandthehighestthroughoutrate
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Whenbasicmulti-usertestingisperformed,theresultsmayvarygreatly,spanningfromvaluesbelowtheanticipatednumberstoratesnearthesingle-userpeakperformanceThereasonforthiswidevariationisduetotwokeyfactors:theoverallbehavioroftheeNodeBsschedulingandtheenvironmentforeachindividualuserItisthereforeimportanttosetupthetestinarepeatablewaytoensurethatresultsareusefulontheirownandcanbecomparedagainstsimilartestsineitheradjacentcellsinthesamenetworkorwithcellsthatusenetworkequipmentfromanothervendor
TheprocessofsettingupatesttoverifycellperformancewithmultipleusershastoomanystepstopresenthereindetailInoutlineform,herearethekeysteps:
1 EvaluatethedistributionofsignalqualityinthenetworkthroughexhaustivedriveorwalktestingtobuildaCDF
a IftheCDFsfordifferentcellsaresignificantlydifferent,theendresultwillbesignificantlydifferent
b ThedistributionwilldependonthetypeofterraincoveredandwherethewalkordrivetestisperformedForexample,includingindoorlocationswillproducelowersignalqualitiesthanoutdoor-onlydrivetesting
c Itisexpectedthatroughly80percentoftheLTEdatatrafficwillbegeneratedindoors
2DistributetheUEsaccordingtothesignalqualityCDFtoobtainapropertracprole
a ThechoiceofdistributionshouldmatchnotonlythemeasuredCDFbutalsotheanticipateddistributionofrealusersintherealnetworkForexample,ifitisanticipatedthatseveralusersarelocatedinagroupinapubliclocation(forexample,anairportorcaf)thenitisadvisabletoplacesomeoftheusersinsimilarpatterns
b DifferentMIMOconditionsmightbestressedduetothistypeofdistribution(forexample,multi-usergainsfromMIMO)
3Intherealnetwork,locatetheusersaccordingtotheplanneddistribution
a Notethatitwill benearlyimpossibletogetanexactmatchsoitisimportanttoinsteadlocatetheusersinanareasimilartotheoneidentifiedMakesurethattheactualradioconditionsofthechosenlocationsareloggedandstoredforthecompletedurationofthetest
b Forcasesinwhichsomeoftheuserswillbeinamovingenvironment,makesurethatthiscanbemanagedinacontrolledway
4EnsureOCNGisenabledintheDLfortheadjacentcellstocreateDLloadinginthecell
5EnsurerealisticULloadingisgeneratedfromUEsinadjacentcells
6GeneratetractothetestUEsandensurethateachUEissetuptoreceiveortransmittracwithfullbuers
7Logalloftherelevantparametersasidentiedearlierincludingthelocation(latitudeandlongitude)ofeachUE
a Logallrelevanttrafficfromthenetworkinterfacestoensurethatfullbufferswerepresentforall
UEsinallconditions
b VerifythatallUEswereactiveandthattheindividualUEthroughputratesarerealisticcomparedtoexpectations
8CorrelatetheUEsentireindividualthroughputforMAC,IP,andUDPorTCPlayers
a IfoneorseveraloftheUEsweremoving,theaggregatedthroughputmaychangeovertimedependingontheschedulingandspecificradioperformanceofeachdevicesenvironment
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ItshouldbenotedthatthisisnotarealisticwaytotestacellsactualperformanceinarealnetworkscenariowhenbuffersarenotalwaysfullInstead,itisatestofhowtheeNodeBwouldbehaveinaveryspecificscenarioThiscouldnormallybeconsideredaworst-casescenarioforaspecificdistributionofusers
Realistic multi-user throughput testing
Despitethecomplexity,therearestilllimitationsinmulti-usertestingthatusesfullbufferdownloadsanduploadsInarealistictrafficscenario,usersareexpectedtohaveburstytrafficprofiles,possiblycomprisingHTTP,voice,FTP,IM,e-mail,etcInthefull-buffercase,userswithgoodconnectionsdownloadmoredatathanuserswithlowdatarates,whichbiasesresultsAlthoughthisispartlytrue,userstendtodomorewithafasterconnectionthefull-buffercaseisperhapstooextremeThequestion,then,iswhatwouldbeamorerealistictrafficmodel?Woulditbevaluabletopursuethis
testingand,ifso,whatistheaddedvalue?TheanswerdependsonwhichphaseofthetechnologythespecificoperatorisinatthetimeIftheoperatorisabouttoperformvendorselection,thiscouldprovetobeanessentialtesttoensurethattheequipmentbehavesappropriatelyintermsofscheduling,abilitytodeliverthedesiredQoS,andoverallfairnesstothedifferentusers
ItisalsoimportanttounderstandthatdeliveringtheexpectedQoSorbeingabletoprovidefairnessinthesystemisnotnecessarilyadifficulttaskforaneNodeBInpractice,thedifficultyistheabilitytodelivertheexpectedQoSwithaminimumofoverheadfactorsthatimpacttheoverallcellcapacity
Thefollowingisaproposedtesttohighlightcertainpossibledeficienciesinasystem
1QoSoverheadprovisioninganalysis
a Setupastaticmulti-usercelldownloadwith6to10usersperformingfull-bufferdownloads
b Measuretheoverallcellcapacity
c Reassignoneuserasamobileuserwithafixed-rateUDPstreamwiththesamemegabit-per-secondratethatwasachievedinthefull-bufferdownload
i SettheQoSparametersforthisusertomatchthefixedrateoftheUDPstream
ii Verifythatthethroughputrateisintherangeof2to5Mbps
d Measuretheoverallcellcapacity
e Movetheuserfrommediumtopoorradioconditioninfivestepsandrepeatthecell-capacitymeasurementsforeachstep
f Movetheusertothecelledgeforthespecificdataratethatwasprovisioned
g Measuretheoverallcellcapacity
ComparethecellcapacityrstwithandthenwithouttheQoSprovisionedforthebandwidththatcanbedeliveredwithoutanyactualimpactontheoverallcellcapacityencompare,stepbystep,theoverallimpactofusermobilityoncellcapacityandguaranteedQoS
2Testtheimpactofrealistictracbehaviorontheoverallscheduling
a Setupagroupofusers(6to10)witharealistictrafficprofileforthetypeofusersenvisionedfortheLTEnetworkThefollowingareexamplesofusescenarios
i Downloadfivewebpageswitha30-seconddelaybetweeneachdownloadEachpagecontains20objectsforatotalof14MBperpage
ii Receiveane-mailmessagewithalarge(forexample,10MB)attachment
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iii Send10e-mailmessages,fourwith2-MBattachmentsandsixsmalloneswithonly50KBofdataineach
iv ListentoInternetradio(256Kbps)
v PerformabackgroundFTPdownloadofsevenlargefiles(totalof100MB,similartoamonthlyoperatingsystemupdate)
vi MakeoneVoIPcallusing122KbpsonaguaranteedQoSbearer
NotethatthetestconditionsmustbesetupsuchthattheradiointerfacewillbecongestedincertainconditionsduringtestexecutionUsethepreviouslymeasuredanticipatedcellcapacitynumberstoselectthecorrecttest-caseparameters
b Thesequenceofeventsoccursinparallelforeachuser;however,theusersareseparatedintimeby10secondseach
c EachuserwouldbelocatedinaspecificradioenvironmentdefinedbytheCDFforthespecificcell
d LetthetestruntocompletionwhileloggingalldatafromboththetraceUEsandthenetworkbasedprobesIfpossible,alsologthedatafromtheLTEUuinterface
ThedatashouldthenbeanalyzedtorevealactualbehaviorduringcongestedconditionsOneshouldspecificallystudytheimpactofthescheduleronboththeguaranteedQoStraffic(VoIP)andthestaticRTPstreamfortheInternetradiobecausethesetwoservicesarethemostlikelytodegrade
Asimpleandbasicmeasureistobenchmarkthetotaltimeofcompletionforthetestsequence(excludingtheInternetradiostreamandtheVoIPsession,whichcouldrunindefinitely)Theminimumcompletiontimeshouldberelativelyeasytocalculatebasedonthepreviouslymeasuredperformanceforthemulti-userandfull-bufferdownloadscenariosThedifferencefromthisminimumtimeshouldbeanalyzedtounderstandtheoverallefficiencyofthesystem
AddingmobilitytothistestcasewouldallowforfurtheranalysisHowever,itwouldprobablyaddsomuchcomplexitythatitcouldnotbejustifiedasabasiccase
AllaspectsoftheschedulingandperformanceoftheradioenvironmentshouldbeanalyzedtounderstandtheefficiencyineachlayerandduringeachprocessThiswillalsohelprevealwhichconditionsleadtosuccessfulschedulingresultsandwhichcauseschedulingissues
JDSUcanprovidethetoolsandtheprocessestoexecuteandanalyzetheresultsfromthesetypesoftestsJDSUtoolscanhelpcharacterizethebehaviorandallowforbothcompetitivebenchmarkingandregressiontestingwhenalaundrylistmustbemaintainedforaspecificsupplier
Idle-to-active transition times
OneofthemainexpectationsofLTEistoprovideanalwaysconnectedexperienceforendusersThisisachievedinpartbyensuringaswifttransitionbetweentheidleandactivemodesTheoverallRRC
statemachinehasbeenoptimizedandthenumberofpossiblestateshasbeenminimizedtoensurereducedcomplexity,lowerpowerconsumption,andfastertransitiontimes
Tomeasuretheidle-to-activetransitiontimesonemustbeabletoeitherfullycontrolUEbehaviororbeabletologalloftheassociatedsignalingtoensurethedataisavailabletobemeasuredfromtheoveralltraffic
JDSUtoolscanmeasureidle-to-activetimeaswellasotherrelevanttransactionandproceduraltimesThesemeasurementscanbeperformedusingeitherdatafromatracemobilealoneordatacombinedfromtheLTEandEPCnetworklinkstoenabletruecorrelatedE2Emeasurements
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Latency testing
TheoverallexperienceismorethanthespecificbandwidththatanendusercanreceiveandhowquicklythenetworkwillenableswitchingbetweentheidleandactivemodesTheexperiencealsodependsontheE2ElatencyofapackettransitioningthroughthecompleteEPCandeUTRAN
KPI veriication and calculation
TheJDSUbookLTE and the Evolution to 4G Wireless: Design and Measurement ChallengesincludesanextensivesectionaboutKPIs,thecalculationmethods,andtheoverallmethodology(pleaserefertoChapter6)Asaresult,theKPImaterialcoveredhereiskepttoaminimum
ItisunfortunatethatthephraseskeyperformanceindicatorandKPIhavebecomecommonlymisunderstoodandmisusedAtthemostbasiclevel,aKPIisnothingmorethanastatisticora
measurementHowever,itisthetestobjectiveormarketrequirementforagivenservicethatallowsaparticularstatisticormeasurementtobeconsideredasakeyindicatorofperformance
EventhetermperformancecanmeanverydifferentthingsdependingonthetestingcontextForexample,serviceperformanceforVoIPmaybemeasuredintermsofjitter,latency,anddroppedpacketsNetworkperformancemaybemeasuredbythenumberconcurrentVoIPusersthatcanbeservedwithanacceptablelevelofjitter,latency,andpacketlossThus,whenmeasuringqualityorperformance,oneofthekeychallengesisagreeingondefinitionsthatenableconsistentinterpretationsofresults
Accordingto3GPP,KPIsgenerallyfitintooneoffivecategories:accessibility,retainability,integrity,availability,andmobilityThelistissometimesexpandedtoincludethecategoriesofutilizationandusability
3GPPKPIstandardizationeffortsarelargelyfocusedonmeasurementsrelatedtotheendusers
perceivedQoSThesemetricstendtobemoreoperator-centricastheyrelatespecificallytomeasuringtheabilityofcustomerstoobtainandmaintainaconnectiontothenetworkandtherebymakeuseofoneormoreavailableservices
KPIsarebestunderstoodinthecontextoftheactualobjectiveofthemeasurementEachpartofthenetworkhasdifferentresponsibilitiesassociatedwithdeliveringasingleserviceTherefore,LTE-specificKPIsfocusontheeUTRANitselfand,inmanycases,relyontheeNodeBtoactuallymeasureitsownperformanceOnechallengeforanNEMisdefiningawaytoverifythatKPIscalculatedbytheeNodeBarecorrect,especiallywhenrunningathighloadorfullcapacityAnotherchallengeforbothNEMsandWSPsismakingtheshiftfromsimplylookingatKPIstotroubleshootingandidentifyingtherootcausesofproblems
ForeachKPIcategory,eachservicemayhaveadifferentQoSprofileorQCIlabelToidentifytheperformanceofeachtypeofservicebeingaccessed,themeasurementsshouldbemadeonaper-QCIbasisAdditionalKPIsineachofthesecategoriesshouldbeconsideredinordertoevaluatetheend-to-endusabilityandmanageabilityofaservice
Keyaspectsofawell-designedend-to-endtestsystemarethedatasourcesandthepossiblemonitoringpointsthatexistinanLTEandSAEnetworkSomeofthetopicsdiscussedherearealreadypartoftheindustrystandardsOtherareasmayormaynotbepartoffuturestandardizationeffortsby3GPP,ETSI,orotherindustrybodies
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Fundamentaltothetopicofdatasourcesandmonitoringpointsisanunderstandingofmeasurementtheory,basicphysicallaws,andhowtheLTE/SAEtechnologyworksandisdeployedConsiderthefollowingexamplecommontobothLTE/SAEandUMTSinwhichtwoengineersneedtomeasuretheRRCconnectionsuccessratiointhenetwork
erstengineer,whoisexperiencedindrivetesting,commissionsatargeteddrive-testcampaign,measuringtheRRCconnectionsetupsuccessratioforawideareaClearly,thenumberofmeasurementpointsisdirectlyrelatedtothedurationofthetestingandthenumberofactualattemptsperunitoftimeForthisexample,theengineerconcludedthattheRRCconnectionsuccessratiowas985percent
esecondengineerisaccustomedtonetworkcountersandlink-monitoringtoolsAsaresult,heextractslogsfromthesystemisprovideshimwithareportofalloftheRRCconnectionattemptsforthefullnetwork;hismeasuredRRCconnectionsuccessratiois995percent
Whyisthereadifferenceofnearlyonefullpercentagepoint?Theanswerisfundamentaltotherestofthisdiscussion
Thedifferenceintheresultsisnotduetoflawsinthedatasource,beitthedrivetest,thenetworkcounters,orthelink-monitoringtoolsThedisparityiscausedbythetwoengineersmeasuringdifferentnetworkproceduresfromdifferentangles
edrive-testmethodanalyzesnetworkperformanceasseenfromasinglehandsetatspecicphysicalpointsinthenetworkatdistinctpointsintime
enetworkcountersandlink-monitoringtoolsrecordallofthetracandalloftheoccurrencesofsignalingandusertractheyaredesignedtomonitorisisadierentframeofreference:itanalyzesnetworkperformanceasseenonthenetworkandatthenetworkmonitoringpoints
Differencesbegintoaccumulateifanydrive-testlocationsarewelloutsidetheactual,andpotentially,intendednetworkcoverageareaAsaresult,RRCconnectionrequestsmadeoutsideofthenetworkcoverageareawillberecordedbythedrive-testsystembutnotbythenetworkcountersorlink-monitoringsolutionsThishighlightsakeypoint:anextensivedrive-testcampaignprovidesadditionalinformationbeyondwhatnetworkcountersorlink-monitoringtoolscanprovide
Intheoptimizationcommunity,itisgenerallyagreedthatKPIsshouldbecomparedtoeachotheronlywhentheyarederivedfromthesamedatasourceorwhentheyarenormalizedtoremoveanybiasduetomethodorsourceThisisespeciallytrueifcomparisonsshowunexpectedresultsToday,thelackofpropercomparisonsisoneofthelargestcontributorstounsoundoptimizationdecisionsinthemobileindustryValidcomparisonsandmeaningfuloptimizationcanbeensuredonlyifastringentandcoherentagreementondatasourcesandmonitoringpointshasbeensettledinadvance 3
WhetherengagedintheR&Dprocessortheoptimizationphase,onemustoftenchoosebetweenseveraldifferentstrategieswhendevelopinganLTEtestplanSelectingthemostcost-effectiveandresults-effectivestrategyisoneofthemostimportantdecisionstobemadeearlyineachphaseofthe
workOnceastrategyisselected,theboundaryconditionsofitsapplicabilitymustbeestablishedItisimportanttonotethatastrategythatisappropriateforonephaseoftheworkprobablyhassignificantshortcomingsinanyotherphaseInotherwords,itisseldomagoodideatousethesamefundamentalKPIsbecausethedatasourceswillprovidedifferentresultsindifferentphasesofanetworksdeploymentandmaintenance
3PleasenotethatthisissimplyamatteroffundamentalmeasurementtheoryItisnotintendedtobeadiscussionaboutthepotentialriskofresultsbeingincorrectduetoacertainmeasurementtoolnotworkingasdened
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Toillustratethisidea,consideracaseinwhichQoSiscontrastedwithQoEMonitoringtheend-userIPtrafficonamobilenetworkprovidesafullanddetailedunderstandingofthetrafficflows(TCPorUDP),theapplications(voice,video,HTTP,e-mail,etc),andpotentiallyperformanceSomebelievethatthemonitoringofonlytheUDPorTCPflowswillprovideenoughinformationabouttheend-userQoStobeabletodeduceagoodapproximationoftheend-userQoEAsthefollowingscenarioshows,thisisnotthecaseforapplicationssuchasstreamingvideo
Auseriswatchingstreamingvideoonhishandset,buttheradioqualityisnotsucienttodeliverthefullbandwidthovertheairinterfaceWhentheUDPstreamismeasuredinthecorenetwork,nodegradationoftheRTP/UDPstreamisobservedreeotherlocationsprovideabetterplacetoobservethedegradation:ontheairinterface,ontheusershandset,orbetweenthetwoendpointsoftheRLCentity(intheUTRANbetweentheUEandtheRNCorintheLTEeUTRANbetweentheUEandtheeNodeB)enetworkmonitoringtoolinthecorewouldreportahighandstable
bitrate(goodQoS);however,theenduserwouldreportapoorQoE Shiingthescenarios,assumethattheendusersapplicationisquality-awareand,duetotheradio
conditions,signalsthatthevideostreamingservershouldchangethebitrateofitscodecWhenthisnewRTP/UDPbitstreamappearsonthenetwork,thenetworkmonitoringtoolwillassociatethechangewithalowerQoSstreambecauseithasalowerbitrateOntheotherhand,theradioconditionsaregoodenoughtodeliverthisadaptedbitstream,andtheenduserQoEhasnowincreased
ThisscenarioshowsthatthecrucialelementintheQoEisnotthebitratemeasuredinthecorenetwork,butrathertheend-to-endabilitytodeliveraspecificservicetotheenduserTheapplicationdomainwill,inthiscase,ensurethatthebestpossibleQoEisachievedTherefore,themonitoringtoolmustbeapplication-awaretodelivercorrectQoSmeasurementsthatleadtothecorrectestimationofend-userQoE
Validating LTE voice
Oneoftheto-be-defineditemsfortheEPSishowcircuit-switchedservicessuchasvoice,CSUDIvideo,
SMS,LCS,andUSSDwillbemanagedFouralternativesarecommonlyconsidered
Circuit-switchedfallback(CSFB)
VoiceoverLTEgenericaccess(VoLGA)
VoiceoverIMS(VoIMS)
Proprietaryoptions
CSFBandVoLGAarebothstandardizedandcouldbereadilyimplementedVoIMSislikelytofollowandisanticipatedtobeawidespread,long-termsolutionAmongthese,CSfallbackinEPSisdescribedindetailbelow;theotheroptionsarecoveredinbrief
Anotheraspectthatisnotyetspecifiedin3GPPR8istheuseofavoicecodecSeveraldifferentoptionsareathand;however,duetoalackofagreement,thispartofthestandardizationmightbedelayeduntilR10Onekeyreasonforthedelayisthelackofclarityontheobjective:shouldthequalitybeimproved
orshouldthecapacitybeimprovedbythechoiceofcodec?ItislikelythatachoiceofcodecforinitialEPSdeploymentswillbebasedonamutualbilateralagreementbetweentheUEvendors,theoperators,andtheEPSproviderItwouldnotbeasurpriseifAMRandAMR-WBwereusedinitially
ItiscrucialtounderstandthattheITUhasalreadymovedaheadwiththedefinitionoftheG718codecG718isbuiltontheAMR-WBfoundationand,forthemostpart,providesthequalityofAMR-WBat1265KbpsonthesamecapacityasAMR795KbpsOverall,thismeansthatG718providesa57percentincreaseincapacitywithaverylimitedimpactonspeechdelayAdetaileddescriptionisoutsidethescopeofthispapersothereaderisencouragedtostudyITU-TRecG718infulltofurtherunderstandthistopic
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Application Note: LTE and EPC TestAn Overview of Test Concepts and Tools for Trials 13
Signaling validation
Figure2isatypicalexampleofanIMScallflowforLTEinteractingwiththeSS7networkAswillbeshown,thisisfarfromonlySIPandsomeofthecriticalaspectscannoteasilybeseeninthissimplified
viewOneexampleisthelackofvisibilityintothechoiceofthebearersthathavebeensetupandhowtheymaptoacertainQCI,etc
Anyshort-termanalysisofavoice-over-LTEimplementationwillmostprobablybeimpactedbyoneorseveralshortcutseveniftheintentionistobestandardscompliantThisshouldbeconsideredwhenperforminganalysisanddrawingconclusionsKeyaspectstoconsideraretheusageofROHCfortheairinterface;theusageofacodecforE2EspeechandtheintegrationofapagingprocedurewhentheUEisinidlemode;and,howthemobilitybetweenaccesstechnologieswouldbemanaged
Voice QoS and QoE (MOS)
VoiceQoSandtheresultingQoEisatopicofmanygoodpublicationsandthusthissectionwillnotgointotoomanydetails
Overall,onemustbecarefulaboutwhatistestedunderwhichconditions,andonemustbeawareofthegoverningfactorsthatcontroltheoutcomeIfacertainvoiceserviceistestedwithabearerdeliveringaspecificQoS,thentheresultingvoicequalitywillbelimitedbythequalitydeliveredbythebearer
CALLSETUP
IDLETOA
CTIVE
Originating UE eNB MME Terminating UEPSTNCore IMS
Delay for RACH
scheduling period
Rach preamble
Security ModeCommand + RRC
ConnectionReconguration
RRC ConnectionReconguration
complete
ConnectionRequest
Connection Setup
SIP INVITE
IAMIAM
COTCOT
ACM/CPGACM/CPG
SIP 183 Session Progress
SIP PRACK
SIP 200 OK
SIP 200 OK
SIP 180 Ringing
SIP UPDATE
RRC ConnectionRequest
RRC ConnectionSetup
RRC ConnectionSetup complete +
NAS servicerequest
TA + Scheduling
Figure 2. Typical IMS call ow for LTE interacting with SS7
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Application Note: LTE and EPC TestAn Overview of Test Concepts and Tools for Trials 14
Whilethissoundssimpleintheory,itcausessignificantpracticalconcernsinalmostallnewtechnologiesbeforetheE2EstructureiswellunderstoodInUMTS,voicewasnormallydeliveredusingaradiolinkwithaone-percentBLERtargetCertainimplementationsusedonepercentasaminimumqualitytargetbutover-deliveredonqualityifandwhenresourceswereavailableThismeantthatcomparingasituationinwhichtheBLERwasalwaysheldattheconfiguredBLERtarget(regardlessofavailableresources)andBLERwasadjustedtodeliverthebestpossibleservicewithoutcausingdegradationforothers,theresultsinanunloadednetworkwouldalwaysfavortheflexibleimplementationThisisnotalwaystheintendedtestobjectandthusthevalueofvoice-qualitytestingcanbedegradedorworse,beconsidereduselessTherefore,itiscriticaltounderstandtheunderlyingconditionsthatwillimpactvoiceserviceandtoeithercontrolthesefullyorrecordonlythoseparametersusedThiswillensurefaircomparisonswhenbenchmarkingaresulteitherovertimeorbetweenimplementations
JDSUsuppliestoolsthatcanperformE2Evoice-qualitytestingandalsobenchmarkvoicequalitypassivelyinsidethenetwork(Figure3)
Testing QoS and QoE o LTE streaming video
QoSandQoEmonitoringofavideoserviceisdirectlyanalogoustotheearlierdiscussionofKPIsInshort,allofthesamemethodsandissuesidentifiedintheKPIsectionapplytothesemeasurementsRatherthanrepeatingthatmaterial,pleasereferbacktotheearlierdiscussion
Thereisonekeypointtoadd:understandingvideoQoSandtheresultingQoEshouldbedoneacrossallrelevantaspectsoftheLTEandEPCThismeansthatonecannotonlyidentifytheactualQoSatapointbutcanalsoensuretheserviceupstreamfromthispointifthetrafficflowisgoodatthemonitoredlocationOntheotherhand,ifthetrafficflowispooratthemonitoringlocation,thenafurtherinvestigationupstreamshouldbeperformedNotethatinmanycasestheclientcanusejitterbufferstocompensateforacertainamountandtypeofQoSimpairmentsThus,adegradedQoSdoesnotalwaysleadtothedegradationofQoE
eNB eNB
EPC
JDSU VoIP Office End
UE UE
Serving/PDN
GW
Element Management System /
Network Management SystemJDSU J6804A DNA HD
JDSU J7830A Signaling
Analyzer and J6900A
Triple Play Analyzer
JDSU E6474A NiXt JDSU E6474A NiXt
Figure 3. Network architecture for E2E voice-quality testing
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JDSUprovidesalloftherelevanttoolstomonitorvideoQoSandQoEfromeitherapassiveperspectiveorfromanactiveperspective(Figure4)SupportisprovidedforbothstandardIPTVandforMSTV
Evaluating LTE MIMO and requency-selective scheduling
ComparedtoHSPAsystems,muchofthevalueinLTEcomesfromtheeffectiveusageofbothMIMOandfrequency-selectivescheduling(FSS)Inmanyaspectsthesearetechnologiesthathaveyettobe
provedintermsofaddingrealtangiblevaluetothecustomerinafieldenvironmentTheirrealvaluedependsonthreethings:theactualdeploymentscenario;theoveralltrafficmodeling;and,thespecificimplementationandconfigurationofthesystem
AfeaturesuchasFSSmakesittheoreticallypossibletoaddsignificantperformancetothesystemInpractice,however,performanceislimitedbythealgorithmusedtocontrolschedulingThisisduetooperationaltradeoffssuchasreducingsignificantuplinktrafficforsub-bandCQIreporting,ortechnicalfactorssuchasthepracticalavailablecomputationalperformanceintheeNodeB
AsfarasMIMOisconcerned,itshouldbeunderstoodthatMIMOusageorthemeasurementsleadingtoaspecificMIMOconfigurationforspecifictransmissionstoauserduringaspecificTTIistypicallynotastaticbehaviorWhatsmore,anyexpectationthatMIMOcanbecontrolled,modeled,orunderstoodfromoneorafewmeasurementsistypicallyunrealisticAsaresult,itisimportanttoidentifytwokeyelements:thoseaspectsofthetechnologythatshouldbeevaluatedfromastatisticalbehaviorpointofview;and,thoseparametersthatcanbeanalyzedfromasinglediscretemeasurement
withoutlookingatalargersample
ItisvitaltounderstandandcharacterizetheactualbehaviorofbothMIMOandFSStoensuretheproperdimensioningofthecells,thebackhaul,andtheQoSprovisioningThestatisticalnatureofMIMOandFSScanbewellunderstoodonadetailedTTIlevelonlyiftherighttoolsandprocessareappliedThesecapabilitiesareallavailableusingJDSUtoolsandmethodsThetoolsallowadetailedanalysisandcharacterization,enablingaclearunderstandingofactualbehavior
Figure 4. Tools for monitoring end-to-end LTE QoS and QoE ( VoIP, IPTV, data)
Evolved Node B
Evolved UTRAN (E-UTRAN)
UEs
Uu
Evolved Packet Core (EPC)
MME
S-GWP-GW
Core, Services, IMS
PCRF
MRF
Internet
CSCFHSS
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Testing network coverage
Duringnetworkplanning,modelingisperformedandassumptionsaremadeIftheseareatallinaccurate,theundesirableconsequencesincludeeitherunplannedcoverageholesorunwantedsignalleakageintoadjacentcellsEarlyintheplanningandtuningprocess,aclearunderstandingofactualnetworkcoverageversustheplannednetworklayoutenablestheplanningandengineeringteamtodevelopastrongmethodologythatallowsforverycost-effectivenetworkdeploymentandtuningEarlyverificationofthecoveragewillallowcreationofaCDFofthenetworkperformanceandallowforpropertestingofcellperformance
JDSUprovidesdetailedRFcoveragemeasurementsincludingRSSI,RSRP,RSRQ,andRS_CINRThesecapabilitiescaneffectivelycoveralargenumberofbandsinverycomplexnetworktopologiesTheresultsfromthemeasurementscanbepost-processedwitheithercustomsoftwareoranyoftheindustry-standardpost-processingapplications
Testing LTE handover
CoveragetestingiscloselylinkedtothecharacterizationofHOvalidationandperformanceTofullygraspHOperformance,onehastofirststudyandunderstandtheoverallproceduresandprocessesthatunderliethehandoverinLTEAsiswidelyunderstood,nosofthandoverispresentinLTEAsaresult,thehandoverisalwaysahardbreakbeforemaketransitionTheresultingimpactonend-userQoEmustbeunderstoodandoptimizedItisalsoimportanttounderstandthehandoversoverheadimpactontheeNodeBbecauseLTEhandoverscanbeusedtoproactivelymanageserviceloadinginaspecificarea
Severaldifferenttypesofhandoversarepresent:thosebetweencellsinthesameeNodeB;thosebetweencellsindifferenteNodeBswithoutanyX2dataforwarding;and,thoseinwhichX2dataforwardingisensuringaminimuminterruptionofdatatrafficItiscommonlyunderstoodthattheX2dataforwardingfeaturemightbeimplementedinlaterreleasesoftheeUTRANsoftware;however,some
vendorsmightmakethiscapabilityavailableearlyinthelifecycle
AUEcannormallydiscriminatebetweenthetypesofhandoversbymonitoringtheSFNaroundtheHOtimeandcheckiftheSFNisjumpingoriscontinuous
Figure5isagoodexampleofahandoffbetweentwocellsinasingleeNodeBTheplotshowsthattheBLERisincreasingthemomentsbeforetheHOandthatthisresultsindegradedthroughputontheMAClayerAftertheHOisperformed(forexample,anRRCconnectionreconfiguration),MAClayerthroughputisincreasedandnoBLERisreported
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Followingthisfromasignalingperspective,thecalltrace(Figure6)revealstheresultingHOinterruptiontime,whichisontheorderof12to35msNotethatthisanalysisrequiresaccesstoboththeprotocollogsfromtheUE(orfromapassiveUuprobeorfromaeNodeBfeed)withthosefromthenetworklinks(forexample,S1,X2,etc)
Figure 5. MAC throughput (green line) sags before an RRC event but recovers immediately after.
Figure 6. A call trace can reveal the resulting HO interruption time
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Asinallmobiletechnologies,itisrelativelystraightforwardtoachievesuccessfulhandoversHowever,achievinganoptimizednetworkwithoptimizedhandoversrequiresgreatinsightandtremendousskillintheartofoptimization
Validating LTE backhaul
LTEoffersgreatlyincreasedbandwidthtotheenduserInturn,itisveryimportantthatthisbandwidthcapabilityisavailablethrougheverypartofthenetworkOneofthebigareasoffocusforthisisthemobilebackhaulnetwork,typicallyEthernet,betweenthecellsite(eNodeB)andthecorenetwork
InLTEfieldtrialswehavewitnessedtodate,thewirelessbackhaulnetworkisbroughton-linepriortoimplementationoftheLTE-specifictestcasesCommissioningtheEthernetbackhaulquicklyandeasilyisvitaltokeepinganLTEfieldtrialonscheduleTheJDSUNetCompleteServiceAssuranceSolutionforWirelessBackhaulverifiesEthernetserviceoperationtotrialcellsitesinadvanceoftheLTEtrialexecutionAdherencetoRFC-2544standardsismaintainedwithcost-savingderivedthroughautomationandefficientdeploymentoftechniciansevenacrossmultiplecellsitesHowever,sincesuchtestingisnotuniquetoanLTEfieldtrial,itisbeyondthescopeofthisapplicationnoteGeneralinformationisavailablesuchastheIETFsRFC2544(1999),theIEEE,andtheITUwhichdefinetestandperformancemonitoringmethodologiesforEthernetnetworkinterfacedevices
Veriying LTE handset IOT
ForeachoperatorintheearlyphasesofbringingLTEtomarket,itisessentialtoensureproperinteroperabilityofLTEhandsetsordatacardsOfcourse,theseareearlydevicesthatwillcontinuetoevolverapidlyovertimeConsequently,itisimportanttounderstandthecapabilitiesandensureinteroperabilitybetweenthehandsetandtherelevantnetworkelementsItwillnotbepossibletosimplyrelyonpre-conformanceorconformancetestresultsbecausethesewillseldomreflectactualuserbehaviororissuesfoundintheearlyphasesofnetworkdeployment
IndustryforumssuchasLSTIhavedefinedaminimumfeaturesetandacorrespondingIoDTandIOTtestplanTheseareavailableonlytoLSTImembersandmaybeusedonlyforLSTIpurposesAsaresult,non-membersmustrelyonothermeanstosecurehandsetinteroperabilityAsanLSTImember,AgilenthasmadesignificantcontributionstotheIoDTandIOTphasesThroughthisexperiencepersonnelinbothAgilentandJDSUarebetterabletocontributeeffectivelytothewiderindustry
JDSUprovidesmonitoringtoolssuchastheSignalingAnalyzerthatprovidethecapabilitytoanalyzeandcorrelateinformationfromeachinterfaceandhighlightanydiscrepanciesversustheanticipatedbehavioronasignalinglevelTheJDSUNiXTapplicationcanactivelystimulateahandsettoexecutedifferentapplicationsandtasksThiscorrelatestocontroloftherelevantRFparameters(forexample,fading,MIMOprofiles,etc)andaneffectiveLTEhandsetinteroperabilityenvironmentcanbeprovidedIfappropriatelyandeffectivelyautomated,thiswillensurethatcost-effectiveandreliabletestingisperformed,therebymaximizingassetutilization
Validating device coniguration
OnepartofLTEisyettobefullystandardizedandwidelyagreedupon:theeffectiveperformanceofdeviceconfigurationEvenifsignificantinteroperabilitytestinghasbeenperformed,anyoperatorlaunchinganLTEserviceearlywillberequiredtoremotelyupdatehandsetsandparameterssuchasnetworksettings,software,orotherrelevantparametersduringoperationofthenetwork 4
4ManyofthetraditionalOTAsystemsarebasedonshortmessageservices(SMS)thatarenoteasilysuppliedinanLTEenvironmentwithouttheuseofeitherCSFBIMSorVoLGA,bothofwhicharerelativelycomplexanderror-pronetechnologies
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Itisessentialtoprovidefullvisibilityintodevicebehaviorduringpre-configuration,configuration,andpost-configurationphasesandtocomprehendthefullE2EsignalingneededtodelivertheconfigurationenvironmentWithJDSUtools,thepre-configurationstatecanbeanalyzedbothqualitatively(forexample,theperformanceofalloperationalservices)andinsimplego/no-gotesting(whichservicesworkordontwork)Specificnetworkbehaviorsthatidentifyincorrectlyconfigureddevicescanbeanalyzedanddocumentedtobeusedinsubsequentnetwork-widemonitoringsystemsDuringtheconfigurationprocedure,differenttypesofpositiveandnegativetestingcanbeperformedtostimulateerrorconditionsandtoprovethattheconfigurationissuccessfulifcertainconditionsaremetThenegativeconditionsareespeciallycriticalbecauseitisoftendifficulttoevaluatethestateofanend-userdeviceinarealnetwork
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Appendix: Outline or a Basic Phase 1 LTE Test Plan
Overview
Thissectioncontainsabasicsetoftestcasesthatcanbeusedintwoways:toevaluateLTEasatechnology;and,toassessthebasicperformanceofLTEinfrastructurevendors
Thebasictestplandescribedhereiswell-alignedwiththethinkingofmostinfrastructurevendorsItisalsoconsistentwiththeirdetailedtestplansAsaresult,thissectioncanbeusefultooperatorstooTheycanusethisplanwhenaskingvendorstocreateadetailedoutlinethatspellsouthowtestingwillbeconductedTheoperatorcouldthenvalidatethatthedetailedtestplanmeetstheintentionandbasicexpectationsoftheplanTheoveralltestexecution,datacollection,analysis,andreportingcanbemanagedwithintegrity,ensuringavalidevaluation
Subsequentphasesofatestplancanbeprovidedthatwillallowtheoperatortomovetowardvendorselectionandnetworkroll-out
Thesuggestedtestplanhaseightmajorsections
Achievabledataratesandlatency:single-userthroughputforUL/DLandTCP/UDP
Intra-LTEmobility
Coverageandcapacity
Evaluationofantennacongurationoptions
Self-congurationandself-organizingnetworkfeatures
Evaluationoffrequencyreuse
BasicQoS
Basicapplicationperformance
Below,AchievabledataratesandlatencyhasfoursubsectionsandCoverageandcapacityhastwoEachofthe13totalentriespresentsabasictestoverviewthatcanbeeasilyleveragedintoatestplan
Achievable data rates and latency: single-user throughput or UL/DL and TCP/UDP
Basic test overview
Evaluatesingle-userthroughputacrossarangeofradioconditionsGenerateULandDLloadingof70percentfromadjacentcells
PerformseparateULandDLthroughputtestsindividuallywithTCPandUDPMeasureaveragethroughputfor30secondsduringstationaryconditionseTCPandUDPtestsshouldmeasurelosslessthroughputratherthanrawthroughput
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
Providerawandnormalizedresultsaccordingtothecommontestdescription
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Achievable data rates and latency: cell throughput and MU throughput or UL/DL and TCP/UDP
Basic test overview
GenerateaCDFofthecellaccordingtothecommontestdescriptionPlace10UEsaccordingtotheCDFdistribution
Verifyplacementofthe10UEsinappropriateandrepresentativelocations
GenerateULandDLloadingof70percentfromadjacentcells
PerformseparateULandDLthroughputtestsindividuallywithTCPandUDPMeasureaveragethroughputfor30secondsduringstationaryconditionseTCPandUDPtestsshouldmeasurelosslessthroughputratherthanrawthroughput
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
Providerawresultsandnormalizedresultsaccordingtothecommontestdescription
Achievable data rates and latency: latency
Basic test overview
Evaluatetheend-to-endlatencyinarangeofradioconditionsandloadingscenarios
No-loadscenario
Performend-to-pinginarangeofradioconditionsforaminimumof100samplesperlocationandpacketsize(32,1000,1500bytes)
With-loadscenario
GenerateULandDLloadingof70percentfromadjacentcells
Generatesame-cellDLloadfromoneUEingoodradioconditionswithfullUDPdownload
Generatesame-cellULloadfrom1UEinpoorradioconditionswithfullUDPupload Performend-to-endping(32,1000,1500bytes)inarangeofradioconditionsforaminimumof100samplesperlocationandpacketsize
LogallappropriateparametersandconditionsincludingfulltracesofcontrolanduserplanefromthenetworkandUEsides
ProvideRANandEPClatencyand,ifrelevant,thebackhaultransmissionlatency
Providerawresultsplusminimum,maximumandaveragevaluesforeachradioconditionandpacketsize
Intra-LTE mobility: mobility and handover perormance
Basic test overview
TestandcompareresultsforhandoverbasedonbothS1aloneandonX2forwarding;testsamecell
loadedandunloaded Samemethodologyforboth(S1andX2)testcases
Repeattestforatleast20HOofeachtype
PerformthetestwithDLandULTCPandUDPtracsubsequently
MeasureandreportHOsuccessrate
MeasureandreportcontrolplaneHOtime
MeasureandreportuserplaneHOinterruptiontimeandpacketloss
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LogallappropriateparametersandconditionsincludingfulltracesofcontrolanduserplanefromthenetworkandUEsides
ForloadedHOperformance,testaddtwoUEsingoodradioconditionsinbothcellsperformingfull-buerDLandUL
Othercellloadshouldbe70percentinDLInthemobilitycase,notethatULloadingisnotrequiredduetopracticalissues
Achievable data rates and latency: application perormance
Basic test overview
Fromidlemode,connectanddownloadtheCopernicuswebsite(seecommontestdescription)andmeasurethedownloadtimeinarangeofradioconditionsAminimumofverepetitionsateach
locationisrequiredAminimumofve(10isrecommended)dierentradioconditionsshouldbecoveredfromgoodradioconditionstocell-edgeconditions
eothercellloadshouldbe70percentinULandDL
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
Coverage and capacity radio eatures eiciency and gain assessment: link budget
Basic test overview
Testrstinstaticlocations:
eUEislocatedclosetothecellcenterAUDPDLtransferwithfullbuerisinitiated
eusermovesawayfromthebasestation,sopathlossincreasesRepeatthemeasurementsatthenewlocation
isisrepeatedforatleast10dierentlocationsacrossthecellAmajorityofthelocationsshouldbeinpoorradioconditions;continueuntilcoverageislost
Repeatthesametestwhileinmobileconditions:drivefromcellcentertocelledgeandrepeatseveraltimes
LogallappropriateparametersandconditionsincludingfulltracesofcontrolanduserplanesfromthenetworkandUEsides
Coverage and capacity radio eatures eiciency and gain assessment: scheduler
Basic test overview
LocatefourUEsingoodradioconditionsascloseaspossibletoequalradioconditionsEnsurethatallUEshavethesamepriorityandQoSsettings
SetupDLloadingofUDPwiththefollowingtraccharacteristics:UE1=X;UE2=2*X;UE3=3*X;
UE4=4*XEnsureXischosensothattheaggregatedthroughputoftheusersexceedsthecellcapacity Measuretheresultingbehavior
LocatetheUEsatfourdierentlocationsandgeneratethesameUDPstreamthroughputtoeachUEEnsureaggregatedthroughputoftheusersexceedsthecellcapacity
Measuretheresultingbehavior
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
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Evaluation o antenna coniguration options
Basic test overview
Performthesingle-userthroughputtestcaseandthemultiusercellcapacitytestcasewiththefollowingantennacongurations:
SIMO
2x2MIMO
4x4MIMO(Optional:Performifpossibleforthevendor)
Sel-coniguration and sel-organizing network eatures
Basic test overview
EnsureatleasttwoeNodeBsareoperationalandnoneighborsexistinthetargetcell VerifyintheO&MsystemthatnoneighborsorX2interfacesarecongured
ActivateANRineNodeB
TurnontheUEinacellwherenoneighborsaredenedAerUEreportingofsignalstrengthsofsurroundingsectors,theANRfunctionshalladdneighborstotheneighborlist
Performahandover
VerifyintheO&MsystemthatallcorrectneighborsandX2interfaceshavebeenadded
PerformanHOtoandfromthenewneighbor
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
Evaluation o requency reuse: one deployment scenario
Basic test overview
LocateaUEatthecelledge(in100percentothercellload)andpreparefull-buerdownloads
Withoutothercellload,measureaveragethroughputfor30secondsforbothTCPandUDP
With50percentothercellload,measuretheaveragethroughputfor30secondsforbothTCPandUDP
With70percentothercellload,measuretheaveragethroughputfor30secondsforbothTCPandUDP
With100percentothercellload,measuretheaveragethroughputfor30secondsforbothTCPandUDP
LogallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanesfromthenetworkandUEsides
Comparethecell-edgeperformanceunderthevariousloadingconditionsandcomparethemeasuredSINRforeachloadingconditionatthesamephysicallocation
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Basic QoS: user dierentiation between non-GBR users with dierent QCI
Basic test overview
OneUE(A)shouldhaveafull-buerdownloadofUDPtracingoodradioconditionsandwiththeQCIoflowestpriority
OneUE(B)shouldhaveadownloadofaUDPstreamof10MbpsandbelocatedinmediumradioconditionswithaQCIofsecond-lowestpriority
OneUE(C)shouldhaveadownloadofaUDPstreamof10MbpsandbelocatedinmediumradioconditionswithaQCIofhighestpriority
Measuretheresultingthroughputandpacketloss(onUEBandC)andreporttheactualreceivedthroughputandtheS1andSGithroughput
Othercellloadshouldbe70percentinULandDL
LogallappropriateparametersandconditionsincludingfulltracesofcontrolanduserplanefromthenetworkandUEsides
Note:Toensurethatcongestionoccurs,itmaybenecessarytonormalizethethroughputofUEBandC
Basic QoS: user-dierentiation between GBR and non-GBR users
Basic test overview
Assume:N1>N2>N3>N4(User1hasthehighestpriorityandUser4hastheleastpriority)
LocatefourUEingoodradioconditionsCongureDLbearerswithGBRvaluesforUE1,UE2,UE3,andUE4EnsurethatX1,X2,X3,andX4DLthroughputsareaggregatedabovethecellcapacityatallUElocationsbutthatX1,X2,andX3aggregatedarebelowthecellcapacity
GenerateUDPDLtractoclientsUE1,UE2,UE3,andUE4
StopDLtransferaeratleast30secondsofdatatransfertotheUEclients
MeasureDLthroughput
VerifythattheDLratesforUE1,UE2,andUE3arenolessthantheirpredenedGBRvalues(X1,X2,andX3,respectively)
VerifythatUE4(lowest-prioritytrac)wasthemostnegativelyaected(theDLbitratefailedto
achieveX4,whichisthedesiredDL-GBRforUE4)
ChangetheARPsettingofUE4tobethehighestpriority(N1)
RepeatwithsimultaneousDLtransfertoallfourUEclients
VerifythattheDLdataratetoUE3(lowestpriorityamongallUEs)ismostnegativelyaected(itsdataratewillbelowerthanitsdesiredDL-GBR)
User UE1 UE2 UE3 UE4
GBR DL (Mbps) X1 X2 X3 X4
GBR UL (Mbps) Y1 Y2 Y3 Y4
MBR DL (Mbps) A1 A2 A3 A4
MBR UL (Mbps) B1 B2 B3 B4
ARP (Allocation and Retention Priority is NOT
equal for all ows)
N1 N2 N3 N4
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PerformthesametestbutlimittheS1downlinkperformancetocausecongestionatalevelbelowtheRFcellcapacitybutabovetheaggregatedX1,X2,andX3VerifythroughputisbelowtheS1peakthroughputlimitation
elimitationcanbeachievedviaVLANtuning
Basic application perormance: web browsing, streaming, voice calls, e-mail, VPN, on-line
gaming
Basic test overview
Identifytherelevantservicesforeachlocalenvironment
Selectaheavilytrackedlocalwebsite:
1-5MBforthemainpage(includingimages)
SelectaVoIPapplicationsupportedbytheoperatorandthelocalenvironment(forexample,Skype,GoogleChat,MSN,etc)
SelectalocalcorporatecustomerusingaVPNinamobileenvironment;theVPNconnectionshouldhaveadatarateontheorderof2-10Mbpsend-to-end
Identifythreelocal,well-recognizedservices:
Ahigh-requirement(low-latency)onlinegame
Ahighperformancexed-lineInternetservice(forexample,xDSL,packetcable,etc)
Astreamingvideo(RTP/UDP)service
Executeandcomparetheapplicationperformanceonthefollowingaccesstechnologies:
HSPA(bestlocalcommercialavailableservice)
Fixed-lineInternetservice
LTEingood,medium,andpoorradioconditions Logallappropriateparametersandconditionsincludingfulltracesofthecontrolanduserplanes
fromthenetworkandUEsidesforLTEand,ifpossible,forHSPAandthexed-lineInternetservice
Forthevoiceservice,measureandcompareMOS
Forthestreamingvideoservice,measureandcomparevideoMOSorasubjectivequalitycomparisonwithfriendlyusers
Fortheonlinegame,getasubjectivestatementfromanexperiencedgamerandanE2Elatencymeasurement
Reporttheabsoluteandrelativeperformancebetweenthedierentaccesstechnologies
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Reerences
EPS speciication reerences
3GPP reerences
3GPP TS 23272:CircuitSwitchedFallbackinEvolvedPacketSystem;Stage2
3GPP TS 24301:Non-Access-Stratum(NAS)protocolforEvolvedPacketSystem(EPS);Stage3
3GPP TS 29118:MobilityManagementEntity(MME)VisitorLocationRegister(VLR)SGsinterfacespecification
TS 23401:GeneralPacketRadioService(GPRS)enhancementsforEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN)access
3GPP TS 21905:Vocabularyfor3GPPspecifications
3GPP TS 22278:ServicerequirementsfortheEvolvedPacketSystem(EPS)
3GPP TS 43318:GenericAccessNetwork(GAN);Stage2
TS 23401:GeneralPacketRadioService(GPRS)enhancementsforEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN)access
TS 24301:Non-Access-Stratum(NAS)protocolforEvolvedPacketSystem(EPS);Stage3
TS 29272:EvolvedPacketSystem;MMEandSGSNrelatedinterfacesbasedonDiameterprotocol
TS 33102:3GSecurity;Securityarchitecture
TS 33203:AccesssecurityforIP-basedservices
TS 33210:3GSecurity;NetworkDomainSecurity;IPnetworklayersecurity
3GPP TS Title Protocol Interace(s)
24.301 Non-Access-Stratum (NAS) Protocol for Evolved Packet System (EPS); Stage 3 EPS NAS S1-C
36.413 E-UTRAN: S1 Application Protocol (S1AP) S1-AP S1-C
36.423 E-UTRAN: X2 Application Protocol (X2AP) X2-AP X2-C
29.118 Mobil ity Man agem ent En tity (MME) - Visitor Location Register (VLR) SGs
Interface Specs.
SGsAP SGs
29.168 Cell Broadcast Center Interfaces with the Evolved Packet Core; Stage 3 SBc-AP SBc
29.272 MME Related Interfaces Based on Diameter Protocol Diameter+ S6a, S6d, S13
29.274 Evolved General Packet Radio Ser vi ce (GPRS)
Tunneling Protocol for Control plane (GTPv2-C);
GTPv2-C S3-C, S4-C, S5/8-C, S10, S11-C
29.275 Proxy Mobile IPv6 (PMIPv6) based Mobil ity and Tunn el in g Protocols; Stage 3 PMIPv6 S5, S8 (PMIP)
29.276 Optim ized Handover Procedures an d Protocols betw een EUTRAN Access and
cdma2000 HRPD
S101-AP S101
29.277 Optim ized Handover Procedures an d Protocols betw een EUTRAN Access and
1xRTT Access
S102-AP S102
29.280 3GPP EPS Sv Interface (MME to MSC) for SRVCC Sv Sv
29.281 GPRS Tunneling Protocol User Plane (GTPv1-U) GTPv1-U S1-U, X2-U, S4-U, S5/8-U, S12-U
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TS 33401:3GPPSystemArchitectureEvolution(SAE):SecurityArchitecture;
TS 36300:EvolvedUniversalTerrestrialRadioAccess(E-UTRA)andEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN);Overalldescription;Stage2
TS 23401:GeneralPacketRadioService(GPRS)enhancementsforEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN)access
TS 24301:Non-Access-Stratum(NAS)protocolforEvolvedPacketSystem(EPS);Stage3
TS 29272:EvolvedPacketSystem;MMEandSGSNrelatedinterfacesbasedonDiameterprotocol
TS 33102:3GSecurity;Securityarchitecture
TS 33203:AccesssecurityforIP-basedservices
TS 33210:3GSecurity;NetworkDomainSecurity;IPnetworklayersecurity
TS 33401:3GPPSystemArchitectureEvolution(SAE):SecurityArchitecture;
TS 36300:EvolvedUniversalTerrestrialRadioAccess(E-UTRA)andEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN);Overalldescription;Stage2
TS 36420:X2layer1generalaspectsandprinciples
TS 36421:X2layer1
TS 36422:X2signallingtransport
TS 36423:X2ApplicationProtocol(X2AP)
TS 36424:S2datatransport
TS 29281:GPRSTunnelingprotocolforuserplane(GTPv1-U)
TS 23401:GeneralPacketRadioService(GPRS)enhancementsforEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN)access
TS 36300:EvolvedUniversalTerrestrialRadioAccess(E-UTRA)andEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN);Overalldescription;Stage2
TS 29305:InterworkingFunction(IWF)betweenMAP-basedandDiameter-basedinterfaces
TS 29274:TunnelingprotocolforControlplane(GTPv2-C);Stage3
TS 23060:GeneralPacketRadioService(GPRS);servicedescription;Stage2
TS 36410:S1layer1generalaspectsandprinciples
TS 36412:S1signallingtransport
TS 36413:S1Applicationprotocol(S1AP)
TS 36414:S1datatransport
TS 29281:GPRSTunnelingprotocolforuserplane(GTPv1-U)
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TS 24301:Non-Access-Stratum(NAS)protocolforEvolvedPacketSystem(EPS);Stage3
3GPP TR 22968:StudyforrequirementsforaPublicWarningSystem(PWS)
3GPP TS 22168:EarthquakeandTsunamiWarningSystem(ETWS)requirements;Stage1
3GPP TR 23828:EarthquakeandTsunamiWarningSystem(ETWS),requirementsandsolutions
TS 23060:GeneralPacketRadioService(GPRS);servicedescription;Stage2
TS 23107:QualityofService(QoS)conceptandarchitecture
TS 23203:PolicyandChargingControlArchitecture
TS 23401:GeneralPacketRadioService(GPRS)enhancementsforEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN)access
TS 36300:EvolvedUniversalTerrestrialRadioAccess(E-UTRA)andEvolvedUniversalTerrestrialRadioAccessNetwork(E-UTRAN);Overalldescription;Stage2
TS 23002:Networkarchitecture
TS 23003:Numbering,addressingandidentification
NGMN reerence
wwwngmnorg/uploads/media/White_Paper_NGMN_Beyond_HSPA_and_EVDOpdf
ETSI reerence
ETSI TS 102 250-1:Speech Processing, Transmission and Quality Aspects (STQ); QoS aspects for popularservices in GSM and 3G networks: Part 1: Identification of Quality of Service aspects
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Glossary
AAA authentication,authorization,andaccounting
AMR adaptivemulti-rate
AMR-WB adaptivemulti-ratewideband
APN accesspointname
ASP applicationserviceprovider
BICC bearer-independentcallcontrol
BLER blockerrorrate
BSC basestationcontroller
BTS basetransceiverstation
CAPEX capitalexpendituresCDF cumulativedistributionfunction
CDMA codedivisionmultipleaccess
CLID callinglineidentication
CLIP callinglineidenticationpresentation
CSUDI circuit-switchedunrestricteddigitalinformation
CSFB circuit-switchedfallback
DL downlink
DMT dataminingtoolkit
E2E end-to-end
eNodeB evolvedNodeB;NodeBisaUMTSbasetransceiverstation(BTS)
EPC evolvedpacketcore
EPS evolvedpacketsystem
ESN electronicserialnumber
ETSI EuropeanTelecommunicationsStandardsInstitute
eUTRAN evolvedUMTSterrestrialradioaccessnetwork;alsoabbreviatedasE-UTRANorEUTRAN
FSS frequency-selectivescheduling
GGSN gatewayGPRSsupportnode
GPRS generalpacketradioservice
GUI graphicaluserinterface
HA homeagent
HARQ hybridautomaticrepeatrequest
HLR homelocationregister
HO handoverHTTP hypertexttransferprotocol
IM instantmessaging
IMS instantmessagingservice
IMSI internationalmobilesubscriberidentity
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IP-TV Internetprotocoltelevision
IOT inter-ocetrunk
IP Internetprotocol
IRAT inter-radioaccesstechnology
KPI keyperformanceindicator
LCS locationservices
LSTI LTESAEtrialinitiative
LTE Longtermevolution
MGW mediagateway
MIMO multiple-input/multiple-output
MSC mobileswitchingcenter
MSC-S mobileswitchingcenterserver
MSS mobilesoswitch
MSTV MaximumServiceTelevision
NAI networkaddressindicator
NE networkelement
NEM networkequipmentmanufacturer
NGMN next-generationmobilenetworks
OCNG OFDMAchannel-noisegeneration
OFDM orthogonalfrequency-divisionmultiplexing
OPEX operatingexpenses
OLAP onlineanalyticalprocessing
PCF packetcontrolfunctionPDSN-FA packetdataservingnode,foreignagent
PDSN-HA packetdataservingnode,homeagent
PoC proofofconcept
PSTN publicswitchedtelephonenetwork
QCI QoSclassidentier
QoE qualityofexperience
QoS qualityofservice
QoSM QualityofServiceManager
RNC radionetworkcontroller
ROHC robustheadercompression
RRC radioresourcecontrol
SAE SystemArchitectureEvolution
SC-FDMA single-carrierfrequency-divisionmultipleaccess
SCTP StandardControlTransmissionProtocol
SFN single-frequencynetwork
SGSN servingGPRSsupportnode
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SIP sessioninitiationprotocol
SMS shortmessagingservice
SON self-optimizingnetwork
STP signalingtransferpoint
TDR transactiondetailrecord
TTI transmissiontimeinterval
UE userequipment
UMTS UniversalMobileTelecommunicationsSystem
UL uplink
URI uniformresourceindicator
USSD unstructuredsupplementaryser vicedata
VIP veryimportantperson
VoIMS voiceoverinstantmessagingser vice
VoLGA voiceoverLTEgenericaccess
WAP WirelessApplicationProtocol
WSP wirelessserviceprovider
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Test & Measurement Regional Sales
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