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英文资料翻译系别软件与服务外包学院.专业通信网络与设备.班级0701.学生姓名陈伟.学号100070833.指导教师侯海燕.2010年4月WirelessLANAbstract:ThisarticlediscussestherecentrapiddevelopmentofwirelessLANtechnology,andthroughactualprojectcases,introducedtherelatedknowledge.Inthisnetworkisthecomputerera,alongwiththecablenetworkwidely,byanefficient,flexiblenetworking,wirelessnetworkingtechnologyfortheadvantageofalsodevelopingfast.WirelessLANisacomputernetworkandwirelesscommunicationtechnologycombinedwiththeproduct.Fromaprofessionalpointofview,wirelesslocalareanetworkusingawirelessmultipleaccesschannelisaneffectivemethodtosupportthecommunicationbetweencomputers,andmobilecommunications,personalizationandmultimediaapplicationspossible.Inlayman'sterms,wirelesslocalareanetwork(Wirelesslocal-areanetwork,WLAN)thatisnotthesametimeusingthetraditionalcable,Ethernetortokennetworkfunctions.Computernetworktransmissionmediaoftenrelycopperorfiberopticcable,LANcableform.Butthecablenetworkwiringinsomecasesbesubjecttorestrictions:wiring,rebuildingprojectlarge;lineeasilydamaged;Networknodescannotbemoved.Especiallywhencomparedfromtheremotenodeshouldbeconnected,thelayingofdedicatedcommunicationlinewiringconstructiondifficult,costly,time-consuming,anddemandisrapidlyexpandingnetworkcongestionhasbecomeaseriousbottleneck.WirelessLANisthesolutionoverwirednetworkstoproblems.1.thehistoryofthewirelessLANSpeakingofthehistoricaloriginsofthewirelessnetworkmaybeevenearlierthanyouimagined.Preliminaryapplicationofwirelessnetworkscanbetracedback50yearsagoduringWorldWarII,whentheU.S.Armyusingradiosignalsasdatatransmission.Theydevelopedasetofradiotransmissiontechnology,andusinghighstrengthencryption.U.S.andalliedforceshavehadextensiveuseofthetechnology.Thistechnologyhasbeeninspiredformanyscholars,in1971,theUniversityofHawaii(UniversityofHawaii)researcherscreatedthefirstpacket-basedtechnologybasedonradiocommunicationnetwork,calledALOHNETnetwork,canbeveryearlywirelesslocalareanetwork(WLAN).ThisisthefirstWLANincludessevencomputers,whichusetwo-waystartopology(bi-directionalstartopology),acrossfourHawaiianislands,centralcomputerplacedinOahu(OahuIsland)onthe.Fromthispointonwards,thewirelessnetworkcanbeofficiallyborn.Althoughalmostallofthelocalareanetwork(LAN)architecturearestillwired,butwirelessnetworkapplicationsinrecentyearshavebeenincreasing,mainlyusedinacademia(suchascollegecampuses),medicalindustry,manufacturingandwarehousingindustries,andrelatedtechnologyhasbeeninprogressforbusinessestoconverttoawirelessnetworkisalsoeasier,morecheaper.2.thetechnicalfeaturesofwirelessLANWirelesslocalareanetworkusingelectromagneticwavesintheairtosendandreceivedatawithouttheneedofcablemedia.WirelessLANdatatransferratesnowcanreach11Mbps,thetransmissiondistancecanbefarmorethan20km.ItisthewaythecablenetworkasacomplementandextensiontotheInternetcomputerhasaremovableXing,canquicklyandeasilyresolvedusingthewiredifficulttorealizetheWangluoUnicomproblem.2.1TheadvantagesofwirelessLANComparedwithwirednetworks,wirelesslocalareanetworkhasthefollowingadvantages:(1)installationeasy.Generallyinthenetworkconstruction,thelongestconstructionperiod,thegreatestimpactonthesurroundingenvironmentisthenetworkcablingconstructionproject.Duringtheconstructionprocess,oftenrequirePoqiangdigging,pipethreadingframework.ThebiggestadvantageofthewirelessLANiswaivedorreducedtheworkloadofnetworkcabling,installationnormallyaslongasoneormoreaccesspointAP(AccessPoint)device,youcansetupcoveringthewholebuildingorlocalareanetwork.(2)theuseofflexible.Inthecablenetwork,networkequipment,networkinformationplacedinpositionbythepositionsoftherestriction.Oncecompletedthewirelesslocalareanetwork,wirelessnetworkcoverageareaatanyonelocationcanaccessthenetwork.(3)economical.Lackofflexibilityascablenetworks,whichrequiresthenetworkplannerstoconsiderpossiblefuturedevelopmentneeds,whichoftenleadstolowerutilizationofinformationbydefaultalotofpoints.Oncebeyondthedevelopmentofthenetworkdesignandplanning,wehavetospendmoreforthenetworktransformation,andwirelesslocalareanetworktoavoidorreducetheoccurrenceoftheabove.(4)easytoexpand.Therearemanyconfigurationsofwirelesslocalareanetworkcanbeflexiblychosen.Inthisway,thewirelesslocalareanetworkcanhandleonlyafewcustomersfromsmalllocalareanetworktothousandsofusersoflargenetworksandcanprovidesuchasRoaming(Roaming)andothercablenetworkscannotprovidethefeatures.AsthewirelessLANhassomeadvantages,ithasdevelopedveryrapidly.Inrecentyears,wirelesslocalareanetworkhasbeeninthehospital,shops,factoriesandschools,placesnotsuitablefornetworkcablinghasbeenwidelyused.2.2WirelessLANrelatedtechnologies(1).IEEE802.11standard.IEEE802.11in1997byalargenumberoflocalareanetworksandcomputerexperts,approvalofstandards.ProvidesIEEE802.11wirelesslocalareanetworkoperatesinthe2.4GHzband,thebandwasdefinedasaglobalentityofradiospectrumuseregulationsbands.August1999,the802.11standardhasbeenfurtherimprovedandrevised,includingtheuseofanSNMP-basedMIBtoreplacetheoriginalOSIbasedprotocolMIB.Italsoaddstwoelements,one802.11a,whichextendsthestandardphysicallayer,theband5GHz,usingQFS