WLAN的QOS机制的研究与改进

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1、北京交通大学硕士学位论文WLAN的QoS机制的研究与改进姓名：李晓利申请学位级别：硕士专业：通信与信息系统指导教师：郭宇春20071201』B塞交煎厶堂亟±堂位途塞△旦S!丛￡!ABSTRACTABSTRACT：TheWLANtechnologyhasbeenadoptedwidelyincomputerandcommunicationsnetworks．ComparedwiththetraditionalEthemet，WLANhassomepredominantadvantagesintermsofmobility,c

2、onstructivity,maintainability,anti-jammingandsecurity,whichmakesiteasieraccesstoportabledevicesandLANSandmoreefficienttotransmitimageinformation，voicemessageandemail．Withtheriseoftime—delaysensitivitybusinessre．g．video)andthelimitationofnetworkbandwidthresources，t

3、herequirementoftakingassuranceofQoSintoapplicationisbroughtonexigently．Thechannel·accesstechnologyintheMAClayeristhecruciallinkfortheassuranceofQoStechnology．SoitisimportanttoresearchtheaccesstechnologyintheWLANMAClayer．IEEE802．1lxprotocolsarethemainstreamprotocol

4、sinWLANtechnologieswhichmainlyprescribetheaccesstechnologiesintheMAClayer．Primarily,thispaperwillmakearesearchontheaccesstechnologiesintheMAClayeranddoananalysisontherealizationmechanismsofthePCFandDCFthatisdeeplyanalyzedbasedonMarkovchainmodelproposedbyBianchiand

5、thenmakeadiscussionandconclusionabouttheconsandprosofQoSmechanismsbasedonIEEE802．11．Next，thispaperwillmakeadetailedintroductiononaccessmechanismsintheMAClayeraswellasQoSmechanismsbasedonIEEE802．1leanddoananalysisontherealizationdifferencebetweenIEEE802．11andIEEE80

6、2．1leusingQoSmechanismsandthendrawaconclusionaboutadvantagesofEDCAOVerDCEFinally,inconformitytotheMarkovchainmodelthispaperwillmakeananalysisonrelationshipsamongEDCAthroughput，timedelay,thenumbersofSTAandthevalueofCW,andherebyaccordingtodynamicsetupandvalueofnetwo

7、rkstatuspresentanimprovedscheme⋯DEDCAscheme，whichisvalidatedthatitisbetterthanEDCAbycomparingthethroughoutandtimedelaywiththeemulatingofthesetwoschemesusingNS2t001．KEYWORDS：WLAN；MAC；DCF；PCF；HCF；EDCA：HCCACLASSNO：TP393．17』b塞銮通厶堂亟±堂僮j金塞国目塞图目录图2-1BSS结构图⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯

8、⋯⋯⋯⋯⋯⋯⋯⋯⋯．12图2—2ESS结构图⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯．13图2—3无线局域网基础设施网络结构⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯．14图2-4AdHoc网络结构⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯14图2．5MAC帧格式⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯