资源描述:
《802.11 Power-Saving Mode for Mobile Computing in Wi-Fi hotspots》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、802.11Power-SavingModeforMobileComputinginWi-Fihotspots:Limitations,EnhancementsandOpenIssuesG.Anastasia,M.Contib,E.Gregorib,A.Passarellab,∗PervasiveComputing&NetworkingLaboratory(PerLab)aDept.ofInformationEngineering,UniversityofPisaViaDiotisalvi2-56
2、122Pisa,Italyg.anastasi@iet.unipi.itbCNR-IITInstituteViaG.Moruzzi,1-56124Pisa,Italy{marco.conti,enrico.gregori,andrea.passarella}@iit.cnr.itAbstract.NowadaysWi-Fiisthemostmaturetechnologyforwireless-Internetaccess.Despitethelarge(andeverincreasing)dif
3、fusionofWi-Fihotspots,energylimitationsofmobiledevicesarestillanissue.Todealwiththis,thestandard802.11includesaPower-SavingMode(PSM),butnotmuchattentionhasbeendevotedbytheresearchcommunitytounderstanditsperformanceindepth.Wethinkthatthispapercontribut
4、estofillthegap.WefocusonatypicalWi-Fihotspotscenario,andassessthedependenceofthePSMbehavioronseveralkeyparameterssuchasthepacketlossprobability,theRoundTripTime,thenumberofuserswithinthehotspot.WeshowthatduringtrafficburstsPSMisabletosaveupto90%oftheene
5、rgyspentwhennoenergymanagementisused,andintroducesalimitedadditionaldelay.Unfortunately,inthecaseoflonginactivityperiodsbetweenbursts,PSMisnottheoptimalsolutionforenergymanagement.WethusproposeaverysimpleCross-LayerEnergyManager(XEM)thatdynamicallytun
6、esitsenergy-savingstrategydependingontheapplicationbehaviorandkeynetworkparameters.XEMdoesnotrequireanymodificationtotheapplicationsortothe802.11standard,andcanthusbeeasilyintegratedincurrentWi-Fidevices.Dependingonthenetworktrafficpattern,XEMreducesthe
7、energyconsumptionofanadditional20−96%withrespecttothestandardPSM.Keywords:802.11,Wi-Fi,Power-SavingMode,NetworkArchitecture&Design,MobileComputing,NetworkProtocols,PerformanceofSystems1IntroductionSincetheintroductionofthe802.11standardin1997,802.11wi
8、relessLANs(alsoknownasWi-Fihotspots)havebecomemoreandmorepopular.InstallationsofWi-Fihotspotsarenowadaysveryfrequent,forexampleincompanyandeducationbuildings,coffeeshops,airports,andsoon.Figure1showsasimpleWi-Fiinstallation,whereuserscarryingm