英文学术报告.ppt

英文学术报告.ppt

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ModelingtheQoEofRateChangesinSkype/SILKVoIPCallsLayoutnBACKGROUNDnPRELIMINARYEXPERIMENTnPROPOSEDMODELFixed-RateModelVariable-RateModelnLARGE-SCALEEXPERIMENTnEVALUATIONnCONCLUSIONANDFUTUREWORKBackgroundnTHEEFFECTIVEend-to-endtransportofdelay-sensitivevoicedatahaslongbeenasubjectofstudyinmultimedianetworking.user-centricapproachrateadaptationmechanismsWeberFechnersLawnEarlyrate-controlmechanismsattemptedtoimproveQoSforthedatadelivered.Anincreasingtrendinthisareaistomeasurenetworkservicesusingthequalityofexperience（QoE）.QoSQoESynergyrateadaptationmechanismsQoE-BasedAdaptationPsychophysicsPRELIMINARYEXPERIMENTMOSbit-rateplotoffixedratetestsThepurposeofthepreliminaryexperimentinthisstudywastoexamine,throughusertests,whetherchangesinsendingratesdecreasestheuserexperience,andatwhatscaletheMOSisinfluencedbythemagnitudeandfrequencyofchanges.PROPOSEDMODELA.Fixed-RateModelwherebristhebitrate,and,andarecoefficientstobedeterminedbySILKcharacteristics.Thebit-rateshift（）iscausedbythelimitofhumanperception.Accordingtotheformula,thetermbr-,beinginsidetheoperator,canonlybepositive.PROPOSEDMODELB.Variable-RateModelwheretheeffectofchangefrequencyisdistributedtothelogarithmterm,andtheeffectofhrandlrisdistributedtothetwosubroutines,SCALE（）andSHIFT（）.LARGE-SCALEEXPERIMENTA.ANOVATestsNonparallelMOSTrelationshipsindicateinteractionInthat,andarethemeanandstandarddeviationofallscoresobtainedfromtracksofthesame（hr,lr）pair.Thez-scorewasthenusedforANOVAtests.LARGE-SCALEEXPERIMENTB.ModelSpecifics1）CoefficientsofFixed-RateFormula2）SubroutineofVariable-RateFormula3）SubroutineofVariable-RateFormulaEVALUATIONA.PredictionAccuracyGoodnessoffitoftrainingdataThescatterplotinFigshowsthefittedscore（asthe-axis）andtheuserscore（asthe-axis）foreachratepairandtimeintervaltestsetEVALUATIONA.PredictionAccuracyAccuracyofpredictionFigshowstheaccuracyoftheproposedmodel.Inthisfigure,thepredictionsofbothdatasetscloselytrackthemeasureddata,regardlessofthedifferenceinaudiocontentandspeakerEVALUATIONB.ComparisontoPESQ1）FixedRatePredictionerror:

SILKversusPESQforfixed-ratetracksForthefixed-ratecomparison,weincludedtracksinboththepreliminaryandlarge-scaleexperimentEVALUATIONB.ComparisontoPESQ2）VariableRatePredictionerror:

SILKversusPESQforfixed-ratetracksAsimilarcomparisonwasalsoconductedforvariabletracks,andtheaccuracyofpredictionofboththeproposedmodelandPESQareindicatedinFigCONCLUSIONANDFUTUREWORKA.QoEMeasurementInthisstudy,wequantifytherelationshipbetweenuserexperienceandbitratechangesforSkype/SILKcalls.B.NetworkDesignAsolidunderstandingofmultimediacontentisfundamentaltobetterengineeringofthenetworkapplications.C.MultimediaContentTakingSkypeasthefirstresearchtarget,thisstudyinvestigatestheinfluenceofdifferentbitratesandratechangesofaudiostreamsproducedbytheSILKcodec.ThankYou!