无线网路的概观与80211无线区域网路（Overview）ppt课件.ppt

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1、IEEE802.11OverviewRong-HongJanDeptofComputerandInformationScienceNationalChiaoTungUniversity802.11Technologies:Past,PresentandFutureApprovedandnear-term802.11LetterStandardsFaster:Standards-basedWi-Finowdeliversdataratesupto54MbpstoWi-Ficlients.(11a,11g)Better-performing:Theneedforabetter-performin

2、gMAChasbeendrivenbydemandingapplicationsuchasvoiceandvideo.QualityofServiceenhancementshavemodifiedtheMACtoprovideadmissioncontrolandprioritizedchannelaccess.(11e)3Moresecure:Securityenhancementshavebeendevelopedtoaddressaccesscontrolandauthenticationanddataprivacyandintegrity,drivenbythemarketrequi

3、rementforenterprise-levelsecurityinwirelessLANs.(11i)Broaderapplicability:Regulatoryenhancementsthatbroadentheapplicabilityof802.11tootherfrequenciessuchas4.9GHzinJapanandotherregulatorydomains.(11j)4PhysicalLayerenhancements11a,11b,11gQualityofService(QoS)enhancements11eSecurityenhancements11iWPARe

4、gulatoryenhancements11d11h5Future802.11Standards802.11jThe802.11jTaskGroupisworkingonJapaneseregulatoryextensionstoallowforoperationinthe4.9GHzand5GHzbandsinJapan.Thisisexpectedtobeapprovedin2005.802.11k802.11kisfocusedonstandardizingtheradiomeasurementsthatwillallowuniformmeasurementofradioinformat

5、ionacrossdifferentmanufacturerplatforms.6Byhavingstandardized,repeatablemeasurements,systemdesignerscanutilizeradioenvironmentinformationtomakebetterdecisionsastofrequencyuse,transmitpowerlevels,etc.802.11nThe802.11nTaskGroupisfocusingoncreatingastandardtofurtherincreasethenetthroughputofwirelessnet

6、works.Thegoalistoachievegreaterthan150Mbpsusablethroughputoveran802.11.7BothphysicalandMAClayerchangesarebeingconsidered,butbackwardcompatibilityisrequired.802.11rThe802.11rTaskGroupisworkingonreducingthehandofflatencywhenclientdevicestransitionbetweenaccesspointsorcellsinanESS.Thisstandardwillfacil

7、itatethedeploymentofSIP-basedVoiceoverWi-Fi(VoWi-Fi)portablephones.8802.11sThe802.11sTaskGroupisworkingonaninfrastructuremeshstandardtoallow802.11accesspointsorcellsfrommultiplemanufacturerstoself-con