基于IEEE802.11B的无线语音性能研究

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1、北京交通大学硕士学位论文基于IEEE802.11b的无线语音性能研究姓名：李大鲲申请学位级别：硕士专业：通信与信息系统指导教师：赵永祥20080601jE京交通叁堂亟±堂位途塞△垦墨!B△￡!ABSTRACTABSTRACT：WiththedevelopmentofthewirelessLANtechnologyandvoiceoverIP(VolP)technology,usingwirelessnetworktotransmitvoiceoverIPbecomesahotresearchdirectionintherecentyears．However,

2、thetraditionalIPnetwork’S‘best-effort’servicemechanismandthelimitedbandwidthofwirelessnetworkmakethewirelessLANunabletoguaranteetheQoSofthereal·timeapplicationssuch弱voice．ThisthesisevaluatesthetransmissionefficiencyofvoiceoverwirelessLAN，proposesaviewpointthat802．1lbnetworksisnotsu

3、itablefortransmitingIPvoice，calculatesandvalidatestheVolPcapacityfromboththeoriesandexperiments，andgivesanewcalladmissioncontrolschemebasedontheexperimentalresults．nestudyinthethesishassomeguidingmeaningtotheuseofVoWLAN，theCACschemehaspracticalsignificationonguaranteeingtheQoSofthe

4、call．AlthoughthetechnologyofusingIEEE802．IlbwirelessnetworkstotransmitIPvoicehasbeenwidelyused，itstransmissionefficiencyisverylow．Mostof802．1lbdevicesadoptDCFtocontendforthechannel．DCFtreatsthevoiceanddataequally,anddoesnotprovideanyaccessprioritytothevoiceapplication．Thesemakeitdi

5、fficulttoguaranteetheQoSofthevoiceapplicationwhichissensitivetodelayandpacketslostratio．neMAClayerofIEEE802．1lbUSeSCarrierSenseMultipleAccesswithCollisionAvoidanceprotocolandthisresultinthelowutilizationrateofthesystem．nepresentthesisanalyzesthefactorswhichaffecttheefficiencyoftheV

6、oWLAN．ConsideringthelowutilizationrateandthehighcostsofconstructingawirelessLAN，thethesisdrawsaconclusionthatitisnotsuitabletotransmitvoiceoverIethatiSbasedontheprinciplesofbaSicaccessschemeunderDCFintheIEEE802．1lbnetworks．Inordertoprovetheviewpoint，thethesisgetstheVolPcapacityinth

7、eidealnetworkenvironmentbytheoreticalanalyzing．rnlevariouskindsofbackgroundflowintherealnetworkswillaffecttheperformanceofthevoiceoverWLAN．nisthesisfurthercalculatesthecapacityofVolPunderthebackgroundflowwithdifferentrate，fromtheperspectiveofdelayandpacketslostratio．Inordertovalida

8、tetheresultsfromthetheoret