《无线基础培训》PPT课件

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1、无线基础知识无线网络分类免费许可频段ExtremelyLowVeryLowLowMediumHighVeryHighInfraredVisibleLightUltra-violetX-RaysAudioAMBroadcastShortWaveRadioFMBroadcastTelevisionInfraredwirelessLANCellular(840MHz)NPCS(1.9GHz)902-928MHz26MHz5GHz(IEEE802.11)HiperLANHiperLAN2802.11a2.4–2.4835GHz8

2、3.5MHz(IEEE802.11)802.11band802.11gUltraHighSuperHigh三种无线技术比较TheLawsofRadioDynamics:HigherDataRates=ShorterTransmissionRangeHigherPowerOutput=IncreasedRange,butLowerBatteryLifeHigherFrequencyRadios=HigherDataRatesShorterRanges802.11b802.11a802.11g2.4GHz5GHz2.4G

3、HzWorldwideUS/APWorldwide11Mbps54Mbps54MbpsFrequencyBandAvailabilityMaximumDatarateOtherServices(Interference)CordlessPhonesMicrowaveOvensWirelessVideoBluetoothDevicesCordlessPhonesMicrowaveOvensWirelessVideoBluetoothDevicesHyperLANDevicesIEEE802.11标准IEEE802.11be

4、cameastandardinJuly19972.4GHzat2MbpsFrequencyHoppingSpreadSpectrum(FHSS)andDirectSequenceSpreadSpectrum(DSSS)IEEE802.11aand802.11bbecamestandardsinSeptember1999802.11a–5GHzat54MbpsOFDM802.11b–2.4GHzat11MbpsDSSSIEEE802.11gisscheduledtoberatifiedin2003802.11g–2.4GH

5、zat54MbpsOFDM802.11promises“true”vendorinteroperability802.11B介绍2.4GHzChannelSetsAmericasEurope,MiddleEastandAsia1234567891011121314CenterFrequency2412MHz2417MHz2422MHz2427MHz2432MHz2437MHz2442MHz2447MHz2452MHz2457MHz2462MHz2467MHz2472MHz2484MHzJapanIsraelXXXXXXX

6、XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXRegulatoryDomainChannelIdentifierChannels-2.4GHzDSSS11“chipsperbit”meanseachbitsentredundantly11Mbpsdatarate3accesspointscanoccupysamearea11Channels–eachchannel22MHzwide1setof3non-overlappingchannels14Channels–eachchannel22MH

7、zwide4setsof3non-overlappingchannels,onlyonesetusedatatime802.11bScalabilityBlue=11MbpsGreen=11MbpsRed=11MbpsTotalBandwidth=33Mbps!!!802.11A介绍802.11aChannelSetsAmericas(FCC)•2.412to2.462GHz;11channels•5.15to5.35,5.725to5.825GHz;12channelsChina•2.412to2.472GHz;13c

8、hannels•5.725to5.825GHz;4channelsETSI•2.412to2.472GHz;13channels•5.15to5.35GHz;8channels•5470to5725MHz;11channelsJapan•2.412to2.472GHz;13channelsOrthogonalFreq