ExploringWirelessNetworking

WirelessLANs

MarketTrends

DifferencesBetweenWLANandLANWLANsuseradiowavesasthephysicallayer.WLANsuseCSMA/CAinsteadofCSMA/CDformediaaccess.Two-wayradio(half-duplex)communication.Radiowaveshaveproblemsthatarenotfoundonwires.Connectivityissues:CoverageproblemsInterference,noisePrivacyissuesAccesspointsareshareddevicessimilartoanEthernethubforsharedbandwidth.WLANsmustmeetcountry-specificRFregulations.

RadioFrequencyTransmissionRadiofrequenciesareradiatedintotheairviaanantenna,creatingradiowaves.Objectscanaffectradiowavepropagationresultingin:ReflectionScatteringAbsorptionHigherfrequenciesallowhigherdatarates;however,theyhaveashorterrange.

OrganizationsThatDefineWLANITU-R:InternationalmunicationmunicationSectorRegulatestheRFusedinwirelessIEEE:InstituteofElectricalandElectronicEngineers802.11documentswirelesstechnicalstandardsWi-FiAlliance:GlobalnonprofitindustrytradeassociationPromotewirelessgrowththroughinteroperabilitycertification

ITU-RwithFCCWirelessISM:industry,scientific,andmedicalfrequencybandNolicenserequiredNoexclusiveuseBest-effortInterferencepossible

IEEE802.11StandardsComparison802.11b802.11a802.11gFrequencyband2.4GHz5GHz2.4GHzNo.ofchannels3Upto233TransmissionDirectSequenceSpreadSpectrum(DSSS)OrthogonalFrequencyDivisionMultiplexing(OFDM)DirectSequenceSpreadSpectrum(DSSS)OrthogonalFrequencyDivisionMultiplexing(OFDM)Datarates[Mb/s]1,2,5.5,116,9,12,18,24,36,48,541,2,5.5,116,9,12,18,24,36,48,54

Wi-FiCertificationWi-FiAlliancecertifiesinteroperabilitybetweenproducts.Productsinclude802.11a,802.11b,802.11g,dual-bandproducts,andsecuritytesting.Providesassurancetocustomersofmigrationandintegrationoptions.CiscoisafoundingmemberoftheWi-FiAlliance.Certifiedproductscanbefoundat.

UnderstandingWLANSecurity

Wireless