电子信息 外文文献译文.docx

电子信息 外文文献译文.docx

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电子信息外文文献译文

XXXX学院

毕业设计（论文）外文参考文献译文本

2012届

原文出处ANovelCross-layerQuality-of-serviceModelForMobileADhocNetwork

毕业设计（论文）题目基于COMNETIII的局域网的规划与设计

院（系）电气与电子信息学院

专业名称电子信息工程

学生姓名

学生学号

指导教师

ANovelCross-layerQuality-of-serviceModel

ForMobileADhocNetwork

LeichunWang,ShihongChen,KunXiao,RuiminHu

NationalEngineeringResearchCenterofMultimediaSoftware,WuhanUniversity

Wuhan430072,Hubei,china

Email:

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Abstract:

Thedivided-layerprotocolarchitectureforMobileadhocNetworks（simplyMANETs）canonlyprovidepartialstack.ThisleadstotreatdifficultiesinQoSguaranteeofmultimediainformationtransmissioninMANETs,thispaperproposesAcross-layersQoSModelforMANETs,CQMM.InCQMM,acorecomponentwasaddednetworkstatusrepository（NSR）,whichwasthecenterofinformationexchangeandshareamongdifferentprotocollayersinthestack.Atthesametime,CQMMcarriedoutallkindsofunifiedQoScontrols.ItisadvantageousthatCQMMavoidsredundancyfunctionsamongthedifferentprotocollayersinthestackandperformseffectiveQoScontrolsandoverallimprovementsonthenetworkperformances.

Keyword:

Cross-layersQoSModel,MobileAdhocNetworks（MANETs）,NetworkStatusRepository（NSR）,QoSControls.

1introduction

Withtherapiddevelopmentofmultimediatechnologiesandthegreatincreaseofhisbandwidthforpersonalcommunication,videoandvideoservicesbegintobedeployedinMANETs.DifferentfromstaticnetworksandInternet,multimediacommunicationsinMANETssuchasVoiceandVideoservicesrequirestrictQoSguarantee,especiallythedelayguarantee.Inaddition,communicationamongdifferentuserscanbeintegratedserviceswithdifferentQoSrequirements.TheseleadtogreatchallengesinQoSguaranteeofmultimediacommunicationinMANETs.Therearetwomainreasonsinthese:

1）MANETsrunsinatypicalwirelessenvironmentwithtime-varyingandunreliablephysicallink,broadcastchannel,anddynamicandlimitedbandwidthandsoforth.Therefore,itcanonlyprovidelimitedcapabilityfordifferentiatedserviceswithstrictQoSrequirements[1].2）Itisdifficultthattraditionalflowprojectandaccesscontrolmechanismareimplementedbecauseofmobility,multiplehopsandself-organizationofMANETs.

Atpresent,mostresearchesonQoSbasedontraditionaldivided-layerprotocolarchitectureforMANETsfocusonMACprotocolsupportingQoS[2],QoSroutingprotocol[3]andadaptiveapplicationlayerprotocolwithQoSsupport[4],andsoon.Itisavoidlessthattherewillbesomeredundanciesonfunctionsamongthedifferentprotocollayersinthestack.ThiswillincreasethecomplexityofQoSimplementationandcausesomedifficultiesinoverallimprovementonthenetworkperformances.Therefore,itisnotsuitableforMANETswithlowprocessingability

Inrecentyears,thecross-layersdesignbasedonthepartialprotocollayersinMANETswasputforward.[1]proposedthemechanismwithQoSguaranteeforheterogeneousflowMAClayer.[5,6,7,8]didsomeresearchesonimplementingvideocommunicationwithQoSguaranteebyexchangeandcooperationofinformationamongafewlayersinMANETs.ThesecanimproveQoSinMANETs’communicationtosomeextent.However,MANETsismuchmorecomplexthanwiredsystemandstaticnetwork,andimprovementsonQoSguaranteedependonfullcooperationamongalllayersintheprotocolstack.Therefore,itisdifficultforthedesigntoprovideefficientQoSguaranteeforcommunicationandoverallimprovementsonthenetworkperformancesinMANETs.

TomakegooduseoflimitedresourcesandoptimizeoverallperformancesinMANETs,thispaperproposesanovelcross-layerQoSmodel,CQMM,wheredifferentlayerscanexchangeinformationfullyandunifiedQoSmanagementsandcontrolscanbeperformed.

Therestofthepaperisorganizedasfollows.CQMMisdescribedinsection2indetail.Insection3,weanalyzeCQMMbythecomparisonwithDQMM.Thesection4concludesthepaper.

2.ACROSS-LAYERQOSMODELFORMANETS-CQMM

2.1ArchitectureofCQMM

InMANETs,presentresearchesonQoSaremostlybasedontraditionaldivided-layerprotocolarchitecture,wheresignalsandalgorithmssupportingQoSaredesignedandimplementedindifferentlayersrespectively,suchasMACprotocolsupportingQoSindatalinklayer[9],routingprotocolwithQoSsupportinnetworklayer[10.11],andsoforth.ItcanbesummarizedasADivided-layerQoSModelforMANETs,DQMM（seefig.1）.

InDQMM,differentlayersintheprotocolstackaredesignedandworkindependently;thereareonlystaticinterfacesbetweendifferentlayersthatareneighboringinlogic;andeachprotocollayerhassomeQoScontrolssuchaserrorcontrolinlogiclinklayer,congestioncontrolinnetwork,etc.Ontheonehand,DQMMcansimplifythedesignofMANETsgreatlyandgaintheprotocolswithhighreliabilityandextensibility.Ontheotherone,DQMMalsohassomeshortcomings:

1）duetotheindependentdesignamonghedifferentprotocollayers,therearesomeredundancyfunctionsamongthedifferentprotocollayersinthestack,2）itisdifficultthatinformationisexchangedamongdifferentlayersthatarenotneighboringinlogic,whichleadstosomeproblemsinunifiedmanagements,QoScontrolsandoverallimprovementsonthenetworkperformances.

Fig.1

Therefore,itisnecessarythatmoreattentionarefocusedonthecooperationamongphysicallayerdatalinklayer,networklayerandhigherwhenattemptingtooptimizeperformancesofeachoflayerinMANETs.Forthisreason,wecombineparametersdispersedindifferentlayersanddesignanovelcross-layerQoSmodel,CQMM,toimprovetheQoSguaranteeandtheoverallnetworkperformances.ThearchitectureofCQMMisprovidedinfig2

Fromfig.2,itcanbeseenthatCQMMkeepsthecorefunctionsandrelativeindependenceofeachprotocollayerinthestackandallowsdirectinformationexchangebetweentwoneighboringlayersinlogicstomaintainadvantagesofthemodulararchitecture.Onthebasicofthese,acorecomponentisaddedinCQMM,NetworkStatusRepository（simplyNSR）.NSRisthecenter,bywhichdifferentlayerscanexchangeandshareinformationfully.Ontheonehand,eachprotocollayercanreadthestatusinformationofotherprotocollayersfromNSRtodetermineitsfunctionsandimplementationmechanisms.Ontheotherone,eachprotocollayercanwriteitsstatusinformationtoNSRthatcanbeprovidedwithotherlayersintheprotocolstack.InCQMM,theprotocollayersthatareneighboringinlogicscanexchangeinformationdirectlyorindirectlybyNSR,andtheprotocollayersthatarenotneighboringinlogicscanexchangeinformationusingcross-layerwaysviaNSR.Therefore,informationexchangeisflexibleinCQMM.

AllkindsofQoScontrolsinCQMMsuchasmanagementandschedulingofnetworkresources,networklifetime,errorcontrol,andcongestioncontrolandperformanceoptimizationandsoonarenotcarriedoutindependently.Onthecontrary,CQMMisinchargeoftheunifiedmanagementandallQoScontrolsbythecooperationamongdifferentprotocollayersinthestack.EachQoScontrolinMANETsisrelatedtoalllayersintheprotocolstack,andalsoconstrainedbyalllayersinthestack.TheresultsofallQoSoperationsandmanagementsarefedbacktothedifferentlayersandwrittenbacktoNSR,whichwillbecometheparametersofallkindsofQoScontrolsinMANETs.

2.2protocoldesigninCQMM

InCQMM,theprotocoldesignsaimsatthefullandfreeinformationexchangeandcooperationamongdifferentprotocollayerstoavoidpossibleredundancyfunctionswhenmaintainingtherelativeindependenceamongdifferentlayersandtheadvantagesofthemodulararchitecture.

Physicallayer:

Physicallayerisresponsibleformodulation,transmissionandreceivingofdata,andalsothekeytothesize,thecostandtheenergyconsumptionofeachnodeinMANETs.InCQMM,thedesignofphysicallayeristochoosethetransmissionmedia,thefrequencyrangeandthemodulationalgorithmwitthelowcost,powerandcomplexity,bigchannelcapabilityandsoon,accordingtothecostofimplementation,energyconstraint,andcapabilityandQoSrequirementsfromhighlayer.

Datalinklayer:

Thelayerislowlayerintheprotocolstackandcanbedividedintotwosub-layers:

logiclinksub-layerandMACsub-layer.Comparedwithhighlayers,datalinklayercansensenetworkstatusinMANETsearliersuchasthechangeofchannelquality,thenetworkcongestionandsoon.Therefore,ontheonehanddatalinklayercanperformthebasicQoScontrolssuchaserrorcontrolandmanagementofcommunicationchannel.Ontheotherone,thelayercanbecombinedwithhighlayerstoestablish,chooseandmaintaintheroutingfaster,preventthecongestionofthenetworkearlier,andchooseappropriatetransportmechanismsandcontrolstrategiesfortransportlayer.

Networklayer:

ThedesignandimplementationofnetworklayerprotocolinCQMMistoestablish,chooseandmaintainappropriateroutingsbytakingintoconsiderationthepower,thecache,thereliabilityofeachnodeinarouting.QoSrequirementsofservicesfromhighlayersuchasthebandwidthandthedelay,andimplementationstrategiesoferrorcontrolinlogiclinksub-layerandthewayofthechannelmanagementinMACsub-layer.

Transportlayer:

InCQMM,theprotocoldesignoftransportlayerneedstobeawareofbothfunctionsandimplementationmechanismoflowerlayerssuchasthewayoferrorcontrolindatalinklayer,themeanstoestablish,chooseandmaintainroutinginthenetworklayer,andQoSrequirementsfromtheapplicationlayer,todeterminecorrespondingtransmissionstrategies.Inaddition,thetransportlayeralsoneedstoanalyzeallkindsof