ORAN設(shè)備集成白皮書 O-RUO-DU Integration Challenges in an Open RAN Environment

sSummary 21.FacilitatingefficienttestingforOpenRAN 31.1SplitoftestresponsibilitybetweenMNOsandVendors 31.2SpecificationofMNOrequirementsformulti-vendorIOT 41.2.1IOTprofiles 41.2.2AdditionalMNOspecifications 41.3Efficienttestingsolution 52.Collaborationandinformationsharingbetweenvendors 52.1SharingofO-RANYANGDataModel 52.2SharingofotherParametersandImplementationDetails 6Conclusion 7Glossary: 7O-RUO-RUItiswellknownthatOpenRANprovidesgreatflexibilitywithitsMulti-VendorEnvironmentallowingoperatorstoselectthemostappropriatesolutionfortheirRadioAccessNetwork.ItnotonlydrivesinnovationinRANbutalsowillreducetheTCOinfuture.However,OpenRANEcosystemcontinuestomatureandassuchcomeswithitsowncomplexities.OneexampleofthisisthetimetakentoonboardandintegratenewO-RU/O-DUcombinationsinthelab,sometimesgoingup2-3months.ForcomplicatedcaseslikeMaMiMoitcanevengoupto9months.ThisnotonlyimpactsthetimetomarketbutalsocreatesabottleneckforafullyopenandeasytoupgradeEcosystem.ThebiggestchallengeinOpenRANistheintegrationofitsnetworkcomponentsprovidedbydifferentHWandSWvendors.WhilstO-RU/O-DUintegrationinvolvesmanystepsfromintegrationplandevelopmenttotesting,thiswhitepaperfocusesonthetestinganddebuggingofO-RU/O-DUintegrations.ReducingthetimeandcosttotestanddebugthisO-RU/O-DUintegrationiskeyinachievingoneofthemainbenefitsofOpenRAN.ThroughthecombinedexperiencethatbothDOCOMOandVodafonehavegainedinOpenRANtestingoverthepastfewyearstheyhaveaccumulatedanumberofkeylearningswhichaddresstheintegrationchallengesbetweentheO-RUandO-DU.Basedontheexperiencesmentionedabove,severalrootcauseshavebeenidentifiedthatposeachallengetoefficientO-RU/O-DUintegration.Forthebenefitofthisdocumentthesearehighlightedbelow.?Differentinterpretationsofthe3GPPandO-RANspecifications.?IncompatibilitiesbetweentheO-RUandO-CU/DUcausedbyoptionalityprovidedinO-RANspecifications.?ProductexclusionofmandatoryfeaturesdefinedinO-RANspecifications.?UseofdifferentversionsofspecificationbytheO-RU/O-DUvendors.ThesemisunderstandingsseemtobeduetothemiscommunicationbetweenvendorsandthusitbecomesimportantthatMNO’scollaborateswiththevendors,e.g.bysharingasetofrecommendedparametersandconfigurations,whichwillallowthemtoworkincollaborationasperMNO’srequirements.MMNOOO-DUFigure1.RepresentscollaborationbetweenMNOandVendorsInthisdocument,weaddressthemajorissuesleadingtomentionedrootcausesandproviderecommendations.ItisvitaltohavecommonunderstandingonthetestresponsibilitybetweenMNOs,O-RUandtheO-CU/O-DUvendors.Firstofall,vendorsshouldberesponsibleoftheirproductimplementationsincludingconformancetoO-RANinterfacespecificationsprovidingthebasisformulti-vendorinteroperability.Vendorsshouldalsohavetheirproducttestedattheirlabs(or3rdpartyopenlabs)beforeworkingwithMNOstoperformE2ETesting.ItisnotedthatthevendorsshouldsatisfytheMNO’sIOTprofile(ref.Section1.2.1)alreadyatthisstagetoensureefficientandsmoothtestinglaterwiththeMNO.?MultiSolutionProviders:SomeVendorsprovidebothO-RUandO-CU/O-DUsolutionsandassuchcanperformapreliminary“single-vendorIOT”priortobringingthedevicetoMNO.?SingleSolutionProviders:VendorsthateitherprovideO-RUonlyorO-DU/O-CUonlymustperformpreliminarytestsusingemulatorswhichcanmimictheO-RU/O-DUandprovidesomereassurancetoothervendorsandMNO’swithrespecttointeroperability.Inaddition,vendorsmayseektoperformsuchtestingatopenlabsincludingOTICsandTIPCommunityLabs.VendorsareencouragedtoobtaincertificationandbadgingthroughOTIC.ThediagrambelowdepictstherecommendedtestingprocessthatshouldbefollowedbythevendorsandMNO’stooptimizetheintegrationactivity.Figure2.RecommendedtestingprocessforO-RU–O-DUIOTAlthoughO-RANinterfacespecificationsprovideenoughdetailstoenablemulti-vendorIOT,theyalsoincludeamultitudeofoptionalfeatures/configurations.Tohelpachievealignmentontheoptionalityandtofacilitatemulti-vendorIOT,O-RANalsospecifiesIOTprofiles.StandardizedIOTprofilesshouldcaterfortheneedsofvariousMNO’sandtheirvariousdeploymentscenarios.AssuchFronthaulspecificationsrequirementsandIOTprofileshavebeenalignedandspecifiedbyO-RANWG4tocoverabroadrangeofusecases(e.g.LTE/NR,FDD/TDD(FR1/FR2),small/macrocell,analog/digitalbeamforming).However,MNO’swillhavetheirspecificrequirements,andassuchitbecomescrucialthattheMNOtakestheownershipoftherequiredIOTprofiletofacilitatesmoothcoordinationbetweenO-RUandO-DUvendors.MNO’smustworkalongsidethevendorstoidentifygapspriortoonboardingthesolutionandallowvendorstoconductpreliminaryinteroperabilitytests.However,tosimplifyfurther,itisrecommendedtohavearationalisedsetofIOTprofilesdefinedinO-RANALLIANCEtocaterfor80%ofrequirementsofMNO’s.ThiswillavoideachMNOcreatingtheirownprofileandwillprovideacatalogueforspecificfeatures(e.g.Beamforming)leadingtosimplification.InadditiontotheO-RANinterfacespecificationsandIOTprofileslayingoutthefoundationformulti-vendorIOT,additionalcomplementaryspecificationfromMNOwouldbenecessaryinpracticetoalignondetailsforrealizingmulti-vendorIOT.Examplesofsuchdetailscouldincluderequirementsonspecificationversions,CUS-planeprocessingcapabilities(e.g.,NumberoffronthaulC-planemessages/sectionsrequiredbytheO-DUbeamformer/schedulerandthatcanbeprocessedbytheO-RU),M-planeYANGparameterpresence,andotherdetailsfoundasrequiredfromIOT.TheseareitemsthatisexpectedtobespecifiedbytheMNObasedonitsrequirementsand/orasaresultofMNOcoordinationwiththevendorsinvolved.SuchadditionalcomplementaryMNOspecificationformulti-vendorIOTwillsignificantlyhelpcoordinationamongvendorsandreducetimeforsuccessfulintegration,especiallyatonboardingofanewO-RUdeviceintoanexistingandcommercialMNO’sOpenRANnetwork.Toreducethetimeandcostofintegration,itiscriticalthattestsolutionsarecreatedtoallowtestingtobeperformedswiftlyandeliminatediscrepancies.Testautomationisessentialinthisregard.Furthermore,scriptstorunthetestequipment(e.g.UE/UEemulators,O-RU/O-DUemulators)whichconnectstothedeviceundertestformanintegralpartoftestautomation,andtheymustbecreatedaccordingtotherequiredparametersofO-RANspecifications.Vendorshavetheknowledgeandskillstocreatesuchtestscripts,itisrecommendedthatthistaskisdelegatedtothevendor.DOCOMO,havinglearntfromitsexperiencewiththetime-consumingintegrationofO-RUwithO-DU,isdevelopinganautomatedtestscriptsuiteatitsLabinYokosukaJapanwiththeaspirationtosignificantlyreducetheO-RUtestandintegrationtime.Vodafone,havingexperiencedsimilarintegrationchallenges,isalsoworkingwithtestsolutionproviderstoimplementtheO-RANtestsolutionatvariouslevelsatitscentrallabinNewbury,UK.Asmentionedabove,automatictestingwillbekeytoshorteningtheintegrationtimebeitinthevendor’slabsforconformanceorMNO/Ecosystemlabsforend-to-endtesting.AssuchrecommendationwouldbeforvendorstodeveloptheirowntestscriptsbasedonMNO’sfeedbackfortestingintheirownlabsorEcosystemlabs.Inadditiontothis,itprovidesincentivefortestproviderstodevelopautomatedtestsolutionsfortheindustry.DuetotheOpenRANmulti-vendorecosystem,informationsharinghasbecomecriticalandintegrationbetweenO-RUandO-DUsimplyisn’tpossiblewithoutcollaboration.Thevendorsmustbepreparedtoworkwitheachotherandallowsharingofinformationsothatintegrationisefficient.Thebelowpointssummarizetheinformationthatmustbesharedandhowitcanhelpinremovingbottlenecksinintegration.InthespecificationsofO-RANALLIANCEWG4,theYANGDataModelisusedtoindicatethestructure,devicestates(idle,active,sleep,etc.),andparametersbetweenO-DUandO-RU.TheMNOshavelearntthattherearecertainpatternsofdiscrepancieswhichtendtoreoccurwhenintegratingtheO-RUandO-DU,resultinginvariouserrorswheninterconnectingthedevicesthroughtheOpenFronthaulM-PlaneandCUS-Planeinterfaces.SuchdiscrepanciesarefoundwithcapabilitiesandconfigurationparametersintheO-RANYANGDataModelsofthedevices,andcanberoughlyclassifiedintofourcategories:1.Inconsistentparametervalue-Incompatibleorwrongtype(i.e.,unit16,Booleanetc.)ofvaluesbetweendevices.2.Missingparameter–AbsenceofrequiredparameterasperMNOrequirements.3.Extraorinvalidparameters-TheparameternotrequiredasperMNOrequirements.4.Unacceptablecharacterstring-invalidcharacter,invalidstring,orsyntaxerror.Therecanbeamultitudeofcausesofthesediscrepancies.GiventhecomplexityofthetaskathandforbothvendorsandtheMNO,simplehumanerroristobeexpected.Butdifferingversionsandinterpretationsofthestandards,ordifferentchoicesofoptionsprovidedbythespecificationscanalsobecauseforthediscrepancy.Deeperrooteddifferencessuchasdesignorimplementationdiscrepanciesarealsoconceivableasanunderlyingreason.Irrespectiveoftheunderlyingcauses,anefficientwaytoidentifydiscrepanciesinanearlyphaseofintegrationwouldbetoperformadesk-basedvisualcrosscheckbetweentheO-RANYANGDataModelsoftheO-RUandO-DUtobeinterconnected.Todothis,theO-DUvendorwouldneedtoshareitsdatamodel,withthefacilitationoftheMNO,totheO-RUvendor,andviceversa.Thecrosscheckingmustbeperformedbybothvendorsandanymismatchmustberemoved.DOCOMOandVodafonehavefounditusefultoperformsuchcrosscheckingwithvendorsinclarifyingthediscrepanciesandreducingthetimeforintegration.Otherwise,eachdiscrepancywouldbefoundduringIOT,andMNOhavingtocoordinatebetweentheinvolvedvendorsforeachandeverydiscrepancywouldbeveryinefficient.BesidestheDataModeldiscussedintheprevioussection,vendorsmustbepreparedtoshareadditionalinformationonotherimplementationspecificparameterstoensureasmoothintegrationprocessandoptimalresults.ThisisespeciallytrueinthosecaseswherethecomputationofafunctionalelementissplitbetweenO-RUandO-DU,requiringbothelementstoexchangeinformationwitheachotherinahighlycoordinated,timing-sensitive,andtightlycoupledmanner.Forexample,withbeamformingmethodsdefinedintheO-RANFronthaulspecificationswherethebeamformingimplementationissplitbetweenO-RUandO-DU,asignificantamountofinformationisexchangedbetweenthetwosubsystemsinatimecriticalmanner.EventhoughO-RANFronthaulspecificationsaddresstheinformationthatneedstobeshared,toeasetheimplementationofthebeamformingmethodespeciallyintheO-RU,itwouldbenecessarytoknowhowexactlytheO-DUwillsendthesectiontypesandwithwhatperiodicity.Theaboveexamplesignifiestheimportanceofinformationsharingandthus,theorderandformatinwhichtheimplementationdetailsareshared