IBM 內(nèi)部 WLAN 培訓資料課件

JeriKorkkiExecutiveITArchitectGlobalSolutionManagerVersion:20May2005Educationpackagefor:

IBMNetworkConsultingfor

WirelessLAN

JeriKorkkiVersion:20May200IBMIntellectualCapitalNoticeThispresentationisforIBMinternaluseonly–DonotgiveacopytoIBMPartnersThispresentationhasbeenpreparedfortrainingIBMGlobalServicespractitioners.NocopyorpartofthispresentationshallbegiventooutsideIBM–includingIBMpartners.However–partsofthispresentationcanbegiventoIBMclientsthroughpaidconsultingengagements.IBMintellectualcapital,theknow-how,techniques,methodologiesandinformationlearnedthroughconsultingandservicesprojects,isofgreatvaluetoIBM.Intellectualcapitalisanassetandshouldberegardedinthesamewayasanyphysicalasset.Sendanyfeedback,corrections,commentsandsuggestionsforchangetoaNotesaddress:JeriKorkki/Finland/IBM@IBMFI2IBMIntellectualCapitalNoticAgendaIBMNetworkConsultingforWirelessLAN–TheofferingWirelessLAN–StandardsWirelessLAN–BasicsWirelessLAN–RequirementsWirelessLAN–EvolutionWLAN–VendorPositioningWirelessLAN–ClientsWirelessLAN–Tools3AgendaIBMNetworkConsultingfIBMNetworkConsultingforwirelessLANIBMNetworkConsultingforwirelessLAN-offeringcontainsfollowingIC:SpecificationsheetSalespresentation–CustomerpresentationSalesguide–HowtosellthisconsultingengagementSampleStatementofWork–IBMlegalapprovedsampleSOWforcustomerengagementsDatacollectionworksheet–tocollectinitialinputforsolutiondefinitionworkshopSolutionDefinitionWorkshopmaterials“How-to-run”guideforNSpractitionersSolutionDefinitionWorkshop-foilsetCaseStudyforaschoolsystemimplementationIBMTechniquePapersSecurityEnhancedWirelessLANArchitecture,StrategyandPolicyfortheEnterprise802.1xAuthenticationFrameworkLEAPClient(Laptop)ConfigurationCiscoAccessPointConfigurationInstallingACSforWLANsWindowsAuthenticationfromaMemberServerUsingClientSecuritySoftwareVersion5.0withTivoliAccessManager802.1xImplementationwithFunkRADIUSserversIBMWECMV5.0capabilitiesanditsenhancedsecurityapplicationsEducationpackage:IBMNetworkConsultingforwirelessLAN–thispresentationEducationpackage:WirelessIPCommunicationsThesematerialscanbeobtainedfromtheICMAssetWeb/services/icm-assetweb/network.nsf/fb255e4d7bdca5b685256452006119f9/9b4a7c8ff47f89b985256dba00668568?OpenDocument4IBMNetworkConsultingforwirSelectedNon-IBMWhitePapers

BelowisalistofusefulwirelessLANsecurityrelatedWhitePaperspublishedbydifferentvendorsandassociations.TheseWhitePapersareavailablefreefromtheWeb–clickthelinks.CiscoSAFE:WirelessLANSecurityinDepth–version2CiscoOverviewofStructuredWireless-AwareNetworkSpreadSpectrumRadiosandRFSafetyWirelessLANEquipmentinMedicalSettings

AddressingtheHealthInsurancePortabilityandAccountabilityActRequirementsWirelessVirtualLANDeploymentGuide(AP1200)AComprehensiveReviewof802.11WirelessLANSecurityandtheCiscoWirelessSecuritySuite802.1xandEAP-BasedAuthenticationacrossCongestedWANLinks

CapacityCoverage&DeploymentConsiderationsforIEEE802.11g

EAP-TLSDeploymentGuideforWirelessLANNetworks

ManagingAironetAccessPointsandBridgeswithCiscoWorksFunkSoftwareSecureAuthentication,AccessControl,andDataPrivacyonWirelessLANsWi-FiAllianceWPA2MediaBriefingWPA2Q&A5SelectedNon-IBMWhitePapersAgendaWirelessLAN–RadioAccessWirelessLAN–StandardsWirelessLAN–BasicsWirelessLAN–RequirementsWirelessLAN–EvolutionWirelessLAN–VendorPositioningWirelessLAN–ClientsWirelessLAN–Tools6AgendaWirelessLAN–RadioAccRadioFrequencyRegulationandLicensing7RadioFrequencyRegulationandFrequencyBandsusedforWirelessLANsystemsExtremelyLowVeryLowLowMediumHighVeryHighInfraredVisibleLightUltra-violetX-RaysAudioAMBroadcastShortWaveRadioFMBroadcastTelevisionInfraredwirelessLANCellular(900MHz)Cellular(1.8-1.9GHz)902-928MHzLegacyUSWirelessLANproducts2.4-2.4835GHz(FCC)2.4-2.4835GHz(ETSIEurope)2.4-2.497GHz(TELECJapan)2.4-2.4835GHz(MII)IEEE802.11bIEEE802.11g5.15-5.35GHz(FCCUNII1&2)5.15-5.35GHz(ETSIEurope)5.15-5.25GHz(TELEC)5.15-5.25GHz(Singapore)5.25-5.35GHz(Taiwan)IEEE802.11aHyperLAN2(Europe)SuperHighUltraHighFCC-FederalCommunicationsCommissionETSI-EuropeanTelecommunicationsStandardsInstituteTELEC-TelecomEngineeringCenter(Japan)MII-MinistryofInformationIndustry(China)8FrequencyBandsusedforWirel2.4GHzIndustrialScientificandMedical(ISM)frequencybandChannelIDCenterFrequencyFCCETSI(EUR)TELEC(Japan)IsraelMII(China)12412XXXX22417XXXX32422XXXXX42427XXXXX52432XXXXX62437XXXXX72442XXXXX82447XXXXX92452XXXXX102457XXXX112462XXXX122467XX132472XX142484XIEEE802.11bstandardallocatedchannelsLicensefreeinmostcountriesSomenationalrestrictionsapply:AvailablechannelsmaybelimitedOutdoorsusemaynotbenotallowedOutputpowerlimitationsAllequipmentmustbetypeapprovedbynationalregulatorEquipmentmustbeconfiguredtomatchcountryregulationsseeIBMTechniquePaper:RegulatoryaspectsgoverningthewirelessLANdeploymentinEuropeChecknationalregulations!!Non-overlappingchannelsinNorthAmericaNon-overlappingchannelsinEurope92.4GHzIndustrialScientificNon-overlappingchannelsinthe2.4GHzfrequencyband2.400GHz2.4835GHz2.4372.4122.4172.4222.4272.4322.4422.4472.4522.4572.4622.4672.472Channel1Channel6Channel11guardband12345678910111213142.4842.4GHzISM(2.4-2.4835GHz)bandavailableinmostcountries2.4-2.497GHzinJapanIEEE802.11bstandarddefineschannelnumberingschemeforDSSSsystemswith5MHzchannelseparationNote:802.11FrequencyhoppingsystemsusedifferentchannelnumberingschemeSomecountriesrestrictchannelusage(i.e.Israel),andJapanhaswider2.4GHzISMbandDSSSchannelsare22MHzwidewith1MHzguardbandsonbothends2.4GHzISMbandallowsmaximumofthreenon-overlappingchannelsguardbands(Japanonly)EuropeChannel1Channel7Channel13Channel1410Non-overlappingchannelsinthLicenseFreeISMBands–Nationaldifferences5.1505.2505.3505.4705.7255.825100MHzBandwidth200MHzBandwidthAustraliaChina/HKEuropeJapanNZ/IndiaSK/SingaporeTaiwanUSA200mWIndoor/Indoor/Outdoor200mWIndoor200mWIndoor200mWIndoor200mWIndoor200mWIndoor200mWIndoor200mWIndoor1WIndoor/Outdoor4WIndoor/Outdoor1WIndoor/Outdoor4WIndoor/Outdoor100mWIndoor/Outdoor4WIndoor/Outdoor2/4WIndoor/Outdoor1WIndoor/Outdoor1WIndoor/Outdoor1WIndoor/Outdoor1WIndoor/Outdoor1WIndoor/Outdoor5.8GHznotuniformlyavailableacrossEuropeandJapanMaybeinfuture100mWEIRPIn/Outdoor10mWEIRPIndoor100mWEIRPIn/Outdoor*10mW/MHzIn/Outdoor100mWEIRPIn/Outdoor100mWEIRPIn/Outdoor100mWEIRPIn/Outdoor4WEIRPIn/Outdoor*)Somecountriesrestrictoutdooruse2.4002.48584MHzBandwidthEveniftheunlicensedISMbandsaremadeuniversallyavailable–therearenationalrestrictions–andthereforeitisofutmostimportancetoknowthelocalregulationsbeforedeployingwirelesssolutions.2.49711LicenseFreeISMBands–NatioSpectrumDesignationinthe5GHzband5.1005.2005.3005.4005.5005.6005.7005.8005.9005.1505.1505.1505.2505.3505.3505.4705.7255.7255.825JapanUSAEuropeIndoor200mW/Outdoor1WEIRPIndoor200mWEIRPOutdoor1WEIRPOutdoor4WEIRPDFS=DynamicFrequencyselectionTPC=TransmitPowerControlFrequencyinGHzDFSandTPCDFSandTPCMaxpeakTXpowerMaxmeanTXpowerNOTE:RestrictionsapplytomultipleEMEAcountries,pleaseseeIBMTechniquePaper:RegulatoryaspectsgoverningthewirelessLANdeploymentinEurope12SpectrumDesignationinthe5RadioFrequencyInterference–RFIWirelessLANsoperateintheunlicensedfrequencybandsthatarefreeforallusers.Accesspointsthatareclosetoeachotherandoperateonthesamechannelcauseinterference.Also,devicessuchascordlessphonesandsomehomeappliancesoperatingon2.4or5GHzbandcauseinterference.RFIaffectstheperformanceofwirelessLANsystemProperlyconductedsitesurveycaneliminatetheriskofRFI2.4and5GHzbandsareunregulatedinmostcountriesoftheworld,however:transmissionpowerisregulatedinallcountries,outdoorsuseislimitedinsomecountriesCompanies“own”theairspaceintheirpremises……butinterferenceoftencomesfromoutside–fromneighboringbuildings,paniesneedtodefinerulesandcarefullytrackplacementofequipmenttopreventRFItherearetechnicalsolutionstocontinuouslymonitortheRFIlevelafterinstallationWirelessLANAccessPointChannel1Channel1CordlessphoneOperatingin2.4or5GHzbandRFIInterference13RadioFrequencyInterference–BestPractices–ToavoidRadioFrequencyInterferenceThereareseveralsourcesofinterferingsignalsthataffectwirelessLANs,includingmicrowaveovens,wirelessphones,Bluetoothenableddevices,andotherwirelessLANs.Themostdamagingofthesearecordlessphonesthatpeoplearestartingtouseinhomesandsomecompanies.Whatcanbedonetoavoidradiofrequencyinterference:AnalyzethepotentialforRFIExecutepropersitesurveytodeterminepotentialRFIsourcesbeforeinstallingequipmentDeployasolutionthatcontinuouslymonitorsRFinterferenceandrogueaccesspointsPreventinterferingdevicesfromoperatingEliminateinterferingdevicesbyturningthemoffEstablishcompanyrulesthatdecidewhichdevicescanoperateandwhereProvideadequatewirelessLANcoverage(adequatefieldstrength)EnsurethattheWLANhasstrongenoughsignalsthroughouttheareaswhereuserswillresideUseantennastoshapethecoverageareaandtrytolimitthesignalwhereitisnotneededConfigureaccesspointsproperlySettheaccesspointstochannelsandpowerlevelsthatavoidRFinterferenceDeploy802.11awirelessLANsThereislesssolutionsthatuse5GHzband802.11ahaseightnon-overlappingchannels–versusthreeinthe2.4GHzband14BestPractices–ToavoidRadiRadioFrequencyShieldingWindowshieldsandshieldingpaintadditives,mixedwithregularpaint,canreducethetransmissionofradiowavesthroughwalls,ceilingsanddoors.

ThisisaneconomicalsolutionforprotectingRFIinterferenceorRFleaksoutofwirelessnetworks.RadioShieldPaintAdditiveMixedwithregularpainttohelpshieldwirelessnetworksWillhelpblockradiowavesandinterferenceEnvironmentallyfriendlyWindowShieldVisiblelighttransmittanceof55%ReducesleakageofradiowavesthroughwindowsHelpsshieldfromoutsideradiowaveinterferencesReducesUVA/UVBrays15RadioFrequencyShieldingWindoDenialofServiceattacksInadditiontoradiofrequencyinterferencethewirelessLANsaresusceptibletoover-the-airdenialofserviceattacks.Withnewradiofrequencymonitoringtoolsandsystemstheattackscanbeeasilyidentified.PreventingDoSattacksisdifficultandcounteringthemusuallyrequiresphysicalintervention.DifferenttypesofDenialofServicesAttacksJammingaradiotransmittersendssignalonwirelessLANfrequencyanddisturbsorpreventsitsoperationdetectthesignalsourceusingRFmonitoringtoolsandremoveitFloodingcontinuouslyrepeatingprobeandregistrationrequestsreducesystemthroughputdetecttheintruderwithmonitoringsystemandremoveitFakeaccesspointscauseclientstoassociatewithwrongaccesspointlocatethefakeaccesspointwithmonitoringsystemandremoveitAttemptstoaccessmanagementinterfacesecureallmanagementinterfacesinaccesspointstopreventmaliciousattacks,suchaschangingconfigurationandrebootingofaccesspoint16DenialofServiceattacksInadRFSafetyalso,see:CiscoWhitePaper:SpreadSpectrumRadiosandRFSafetyThereareconcernsabouthealtheffectsofcellularphonesandwirelessLANsystems.TheeffectsofRFradiationfromwirelessLANequipmenttohumanscannotbedefinitelydismissed–however–thereisnoconclusiveevidenceofwirelessLANshavingaharmfuleffecteither.WLANequipmentmustbytypeapprovedandmeetrelevantstandardsANSIC95.1-1991IEEEStandardforsafetylevelswithrespecttohumanexposureFCCOfficeofEngineeringandTechnologyBulletin65evaluatingcompliancewiththeFCCguidelinesforhumanexposureEN55011limitsandmethodsofmeasurementofradiodisturbancecharacteristicsofISMradio-frequencyequipmentWirelessLANsoperatewithsignificantlylowerpowerthancellphones(<100mW)andinmostcasesthewirelessLANdeviceisnotheldnexttotheuser’searFederalCommunicationsCommission17RFSafetyalso,see:CiscoWhitWirelessLANequipmentinmedicalsettingssee:CiscoWhitePaper:WirelessLANequipmentinmedicalsettingsConcernsaresometimesraisedaboutwirelessLANequipmentoperatingclosetomedicaldevices.WirelessLANsolutionshavebeeninstalledintoseveralmajormedicalfacilitieswithnoreportedcasesofinterference–however:ThereisapossibilityforinterferenceApropersitesurveyandtestingisrequiredbeforedeployingwirelessLANstomedicalenvironmentMedicalequipmentwithintheWLANcoverageareaneedtobeidentifiedandtestedforinterferencePhysicallocation,frequencyband,channelandoperatingpowerofwirelessLANaccesspointanddeviceshouldbeconsideredalongwiththeradiofrequencyimmunitylevelofthemedicaldevicebeforedeployingwirelessequipmentinmedicalenvironments18WirelessLANequipmentinmediHIPAA-HealthInsurancePortabilityandAccountabilityActTheHealthInsurancePortabilityandAccountabilityActpassedin1996inUS,mandatesthathealthcareentitiescoveredundertheActtakeappropriateminimummeasurestoensuretheprotectionofthepersonalinformationoftheirpatients,customers,andpartners.HealthcareindustryisincreasinglyassessingtheabilityofthesolutionstheydeploytoenableHIPAAcomplianceWirelessLANsaregrowinginpopularitywithinhealthcareorganizationsWLANsecurityhascausedconcernsaboutmeetingHIPAAsecuritystandardsandguidelinesEnsuringthatthesecuritychallengesofwirelessLANareaddressedwillbecomenecessarytosuccessfulHIPAAcompliancestrategyCurrentWLANtechnologiesdonotaddressallHIPAAsecurityrequirementsHoweverdeploymentsofwirelessnetworkingsolutions,whencombinedwithothersecuritycontrolsandmechanismswithinthecontextofaneffectiveriskmanagementstrategyandpolicy,caneffectivelymeetthesecuritystandardsasproposedunderHIPAAformoreinformation,see:CiscoWhitePaper-WirelessNetworking:AddressingtheHealthInsurancePortabilityandAccountabilityActRequirements19HIPAA-HealthInsurancePortaAgendaWirelessLAN–RadioAccessWirelessLAN–StandardsWirelessLAN–BasicsWirelessLAN–RequirementsWirelessLAN–EvolutionWirelessLAN–VendorPositioningWirelessLAN–ClientsWirelessLAN–Tools20AgendaWirelessLAN–RadioAccWirelessLANstandards

InstituteofElectricalandElectronicsEngineers–IEEETheInstituteofElectricalandElectronicsEngineerspromotestheengineeringprocessofcreating,developing,integrating,sharing,andapplyingknowledgeaboutelectroandinformationtechnologiesandsciencesforthebenefitofhumanityandtheprofession.IEEEisaninternationalstandardsorganizationIEEEdevelopsstandardsforhundredsofelectronicandelectricaltechnologiesUsesaseriesofnumberstodifferentiatebetweenthevarioustechnologyfamiliesThe802committeedevelopsstandardsforlocalandwideareanetworks(LAN&WAN)802.3committeedevelopsstandardsforEthernet-basedwirednetworks802.15groupdevelopsstandardsforpersonalareanetworks802.11committeedevelopsstandardsforwirelesslocalareanetworks(WLAN)21WirelessLANstandards

InstituWirelessLANstandards

Wi-FiAllianceWi-FialliancehasanimportantroleinthewirelessLANmarket,it-throughitsdefinedtestsuitesandaccreditedtestinglaboratories-certifiesinteroperabilityofIEEEstandard802.11productsandpromotesWi-FiastheglobalwirelessLANstandard.Wi-FiAlliancepromotesinteroperabilityandsecuritystandardsTheWi-FilogoisasymbolofcertifiedinteroperabilityandqualityOver200membercompanies–leadingwirelessequipmentandsoftwareprovidersOver1500Wi-Ficertifiedproducts–providescertifiedproductlistingonWebWi-FiAlliancetracksandpromotessecuritystandardsNOTE:Wi-Filogoisusedwithboth,2.4and5GHzproducts

(theplanforseparateWi-Fi5logonevermaterialized)22WirelessLANstandards

Wi-FiAWirelessLANstandards

IEEEWirelessLANStandardsWirelessLANstandardshaveevolvedovertheyearstoprovidehigherspeeds,compliancetoregionalregulations,vendorinteroperability,qualityofserviceandimprovedsecurity.Currentworkgroupsarelookingintonewapplications,suchasvehicularaccessandmeshedWLANs.StandardPublishedDescription802.111997LegacyWLANstandard–2.4GHzband-FHSS1.6Mbps-DSSS2Mbps802.11b1999Speed:11Mbps–2.4GHzband–Threenon-overlappingchannels802.11a1999Speed:54Mbps–5GHzband-Eightnon-overlappingchannels802.11f2003ProtocolforinteroperabilitybetweenWLANaccesspoints802.11g2003Speed:54Mbps–2.4GHzbandThreenon-overlappingchannels802.11h2003ModificationstocomplywithEuropeanregulations802.11e2004QoSandCoSMechanisms802.11i2004SecurityandAuthenticationenhancements802.11j2004ModificationstocomplywithJapaneseregulations802.11k2005RadioResourceManagement802.11n2006Speed:100Mbps802.11pVehicularwirelessaccess802.11rFastroamingamongaccesspoints802.11sMeshedWirelessLocalAreaNetworks23WirelessLANstandards

IEEEWiWirelessLANstandards

802.11–TheLegacyWirelessLANstandard802.11isafamilyofspecificationsforwirelesslocalareanetworksdevelopedbytheworkinggroupsoftheInstituteofElectricalandElectronicsEngineers(IEEE).Therearecurrentlyfourspecificationsinthefamily:Thelegacy802.11andnewer:802.11a,802.11b,and802.11g.Theoriginal–nowobsolete–802.11standard(w/oasuffixletter)wasratified1997Specifiedan"overtheair"interfacebetween:wirelessclientsandaccesspoints,aswellasbetweenwirelesspeer-to-peerclientsEstablishedtheMAClayerspecificationandthreephysicallayerspecifications:FrequencyHoppingSpreadSpectrum(FHSS)–1.6MbpsDirectSequencingSpreadSpectrum(DSSS)–2Mbps,andDiffusedInfraredAlluseCSMA/CA(carriersensemultipleaccesswithcollisionavoidance)forpathsharingThe802.11isnowobsolete–ithasbeenreplacedby802.11b,aandgstandardsSomeold802.11FrequencyHoppingsystemsarestillinuse24WirelessLANstandards

802.11WirelessLANstandards

802.11a/b/g–Sidebyside802.11a802.11b802.11gFrequencyband5GHz2.4GHz2.4GHzMaxdatarate54Mbps11Mbps54MbpsMaxeffectivedatarate28-31Mbps5-7Mbps28-31Mb/s(inall.11genvironment)10-12Mb/s(inmixedenvironmentwith.11bclients)Otherdatarates48,36,24,18,12,9and6Mbps5.5,2and1Mbpssee:ModulationWirelessmediumOFDM(OrthogonalFrequencyDivisionMultiplexing)CCK-DSSS(ComplementaryCodeKeying-Directsequencespreadspectrum)OFDM(nativemode)CCK-DSSS(for.11bcompatibility)Modulation64-QAMat48and54Mbps16-QAMat24and36MbpsQPSKat12and18MbpsBPSKat6and9MbpsCCKat5.5and11MbpsDQPSKat2MbpsDBPSKat1MbpsOFDM54,48,36,24,18,12,9,6CCKat33,22,11,5.5MbpsDQPSKat2MbpsDBPSKat1MbpsNon-overlappingchannelsEight(FCC=US)Four(Japan,Singapore,Taiwan)ThreeThree25WirelessLANstandards

802.11aWirelessLANstandards

WirelessLANthroughputWirelessLANdataratesaretypicallyquotedas11Mbpsfor802.11band54Mbpsfor802.11aand802.11g.Theactualthroughputhoweverislowerbecauseoftheprotocoloverheadanddelaysassociatedwithaccessingthesharedwirelessmedium.FollowingfactorsaffecttheWLANthroughput:ProtocolOverhead(MACheadersandtrailers)Inter-FrameSpaces(guardtimesbetweenframetransmissions)ACKnowledgementsBack-offtimers(stationsuserandomback-offtimerstocontrolnetworkaccess)Asaresult:Maximumthroughputfor1500bytepacketsinan802.11aandgenvironmentsisapproximately28-31MbpsMaxthroughputinan802.11benvironmentisapproximately5-7MbpsPerformancedegradesaspacketsizesgetssmaller–throughputisreduced54Mbps31Mbps11Mbps6-7Mbps802.11a802.11b54Mbps31Mbps802.11g26WirelessLANstandards

WirelesWirelessLANstandards

802.11g–BackwardscompatibilityimpactsthroughputThroughputdegradationinamixed11gand11benvironmentresultsfromthefactthatboth11gand11ausedifferentmodulationschemes.For802.11gaccesspointtocontrolmixofclientdevicesitmusthaveawaytoknowwhenitistalkingto11bor11gclients:thisiscalledthe11gProtectionMechanism.802.11gaccesspointslowsdowninmixed11band11genvironments802.11bdevicesuseCCKmodulation–802.11gdevicesuseOFDMmodulationForbackwardscompatibility,APmustsupportbothmodulationtechniques802.11bdevicescannotdetectOFDMDestroysCSMAchannelaccess-802.11band802.11gclientstransmitovereachother802.11gAPmustenableprotectionmechanismif802.11bnodeassociateswithitProtectionmechanismtransmitsaCTSframebeforesendinganOFDMframeThiscausesathroughputimpactacrossthewholecellMaxeffective802.11gdatarateis28-31MbpsMaxeffectivedataratewithprotectionenabled13.5Mb/s27WirelessLANstandards

802.11gWirelessLANstandards

802.11g–Offersbackwardscompatibilityataprice802.11gAccessPoint802.11gclient802.11gclientEffectivethroughput28-31Mbps802.11gAccessPoint802.11bclient802.11gclientEffectivethroughput~13Mbps802.11a/bdualAccessPoint802.11bclient802.11aclientEffectivethroughput28-31Mbps802.11band802.11g802.11gOnlyNetwork802.11band802.11aAstudyperformedbyIntelinamixed802.11band802.11genvironmentdiscoveredasignificantdropintheeffectivedatathroughput.The802.11geffectivethroughputof~21Mbpswilldropdownto~13Mbpsinmixed802.11band802.11genvironment.802.11a/bisabettersolutionthan802.11gandbinamixedenvironmentOFDMOFDMOFDMCCKOFDMCCK28WirelessLANstandards

802.11gWirelessLANstandards

HiperLAN2ETSI(EuropeanTelecommunicationsStandardsInstitute)developedEuropeanwirelessLANstandard.Technologicallysuperiorto802.11a,butastherearenocommercialHiperLAN2productsonthemarketEuropeanregulatorshavestartedtoapprove802.11aproducts.KeyfeaturesofHyperLAN2standardOperateson5GHzband–withnominalspeedof54Mbpsmax.datarateof42Mbpscomparedto802.11amax.of18Mbpsfor512bytepacketsDynamicFrequencySelection(DFS)–AutomaticFrequencyPlanningTransmissionpowercontrolhelpstominimizeRFIinterferenceQoSforreal-timemultimediacommunicationEfficientpowersavecontrolforintegrationintoportabledevicesConvergencelayeroffersbackbonenetworkindependenceinteroperabilitywith:

-Ethernet

-IEEE1394(Firewire)

-ATM

-3G(thirdgeneration)29WirelessLANstandards

HiperLAWirelessLANstandards

802.11h–SpectrumandTransmitPowerManagement802.11haddressestherequirementsoftheEuropeanregulatorybodies.Itprovidedynamicchannelselection(DCS)andtransmitpowercontrol(TPC)fordevicesoperatinginthe5GHzband.InEurope,there'sastrongpotentialfor802.11ainterferingwithsatellitecommunications.TPC(TransmissionPowerControl)Supportsinterferenceminimization,powerconsumptionreduction,rangecontrolandlinkrobustnessTransmissionPowerControlproceduresinclude:AccesspointsdefineandcommunicateregulatoryandlocaltransmitpowerconstraintsStationsselecttransmitpowersforeachframeaccordingtolocalandregulatoryconstraintsDCS(DynamicChannelSelection)AccesspointsdecidethechannelonwhichtheyoperateClientsprovidedetailedreportsaboutspectrumusageattheirlocations30WirelessLANstandards

802.11hWirelessLANstandards

802.11f–InterAccessPointProtocolLegacy802.11standarddidnotspecifythecommunicationsprotocolbetweenaccesspointstosupportusersroamingfromoneaccesspointtoanother.The802.11workgrouppurposelydidn'tdefinethiselementinordertoprovideflexibilityinworkingwithdifferenttypesofwiredLANnetworks.Without802.11f,roamingisnotassuredbetweendifferentvendorsaccesspointsToassureroamingpriorto802.11f–useaccesspointsfromsamevendorunlessvendorsguaranteeinteroperability802.11fisthenewstandardforinteraccesspointroamingenablesfreemixofaccesspointsfromdifferentvendors802.11fonlyassuresroamingbetweenlayer2connectedaccesspointsMobileIPorvendorproprietarysolutionsareneededforlayer3roamingSecurityfeaturesworkover802.11froamingAccessPointwith802.11fsupportAccessPointwith802.11fsupport31WirelessLANstandards

802.11fWirelessLANstandards

802.11e–QualityofServiceThepurposeof802.11estandardistoenhancethe802.11MACtoexpandsupportforapplicationsthatrequireQualityofService.QoSfeaturesandmultimediasupportisaddedtotheexisting802.11b/g/awirelessstandards,whilemaintainingfullbackwardcompatibilitywiththesestandards.802.11ebringsstandardizedQualityofServicetowirelessLANnetworksenablesIPCommunications:voiceandvideoapplicationsNewQoSmechanism:HCF(HybridCoordinationFunction)ReplacesthelegacyDCF(DistributedCoordinationFunction)andPCF(PointCoordinationFunction)WithinHCF–therearetwoaccessmechanisms:EDCA–EnhancedDistributedChannelAccessContention-basedchannelaccess-ProvidesdifferentiationforchannelaccessbytrafficclassTriggeredAPSD(AutomaticPowerSaveDelivery)isoptionalHCCA–HCFControlledChannelAccessGuaranteedperformance–basedonpollingUsesScheduledAPSD-suitableforpowersave802.11eisbackwardscompatiblewi