简介:活动特定的网络(MANET)是有能是的无线移动式节点的一种很复杂的分布式的通信系统自由地并且动态地self-organizedinto任意、暂时的网络拓扑。MANET继承无线网络的几限制,同时使从MANET的特性产生的新挑战例如线路失败,隐藏终端和暴露的终端。当TCP在MANET环境被使用时,问题不得不被处理的流氓的棕土。在这篇论文,这块动态地上的全面调查被给。明确地,第一次,损害TCP性能的所有因素基于网络协议分级被识别,即,在物理层的有损耗的无线隧道;在MAC层的过多的竞争和不公平的存取;在网络层,MAC层和网络层的脆弱的路由选择协议联系了移动式节点;在传送层和传送层的不适宜的拥挤窗口大小联系了不对称的路径。这些因素怎么降级TCPperformance清楚地被解释。基于怎么减轻每上面列出的这些因素的影响,然后,存在答案尽可能包括地被收集并且分类进很多个范畴,和他们的优点和限制被讨论。这些答案的基于的在限制,为设计更柔韧的答案的一套开的问题被建议。
简介:Broadcastisanimportantoperationinmanynetworkprotocols.Itisutilizedtodiscoverroutestounknownnodesinmobileadhocnetworks(MANETs)andisthekeyfactorinscalingon-demandroutingprotocolstolargenetworks.ThispaperpresentstheAdHocBroadcastProtocol(AHBP)anditsperformanceisdiscussed.Intheprotocol,messagesareonlyrebroadcastbybroadcastrelaygatewaysthatconstituteaconnecteddominatingsetofthenetwork.AHBPcanefficientlyreducetheredundantmessageswhichmakeflooding-likeprotocolsperformbadlyinlargedensenetworks.Simulationsareconductedtodeterminetheperformancecharacteristicsoftheprotocol.ThesimulationresultshaveshownexcellentreductionofbroadcastredundancywithAHBP.Italsocontributestoareducedlevelofbroadcastcollisionandcongestion.
简介:Mobileadhocnetworks(MANETs)aregainingalotofattentioninresearchlatelyduetotheirimportanceinenablingmobilewirelessnodestocommunicatewithoutanyexistingwiredorpredeterminedinfrastructures.Furthermore,inordertosupportthegrowingneedformultimediaandrealtimeapplications,qualityofservice(QoS)supportbythenetworkingprotocolisrequired.SeveralimportantQoSparametersthatareneededbysuchapplicationscanbeidentified.Theyincludebandwidth,end-to-enddelay,delayjitter,andbiterrorrate.Agoodamountofresearchhasbeendevelopedinthisareacoveringdifferentissuesandchallengessuchasdevelopingroutingprotocolsthatsupportbandwidthreservationanddelaymanagement.Inthispaper,thecurrentstateofresearchforQoSsupportinTDMA-basedMANETsatdifferentlayersofthenetworkingmodelispresentedandcategorized.Inaddition,thecurrentissuesandfuturechallengesinvolvedinthisexcitingareaofresearcharealsoincluded.
简介:Inthispaper,anopportunisticcooperativeadhocsensornetworkwithrandomlylocatednodesisanalyzed.Therandomnessofnodes'locationsiscapturedbyahomogeneousPoissonpointprocess.Theeffectofimperfectinterferencecancellationisalsotakenintoaccountintheanalysis.Basedonthetheoryofstochasticgeometry,outageprobabilityandcooperativegainarederived.Itisdemonstratedthatexplicitperformancegaincanbeachievedthroughcooperation.Theanalysesarecorroboratedbyextensivesimulationresultsandtheanalyticalresultscanthusserveasaguidelineforwirelesssensornetworkdesign.
简介:提出一个联合传输速率、链路的传输时间和链路速率的网络利用最大化模型(NUM),并用对偶分解理论设计该问题的分布式算法。目标是为了得到传输层的最优的端到端的源速率,物理层的功率以及MAC层资源的最优分配,从而使网络利用率达到最大的同时使所有链路的功耗最小。通过仿真实验,验证算法的可行性,能达到预期的目标。
简介:在过去几年,无线联网技术成为了广阔在我们的每日的生活袭击。在无线特定的网络,没有任何永久基础结构,连接由很多个单位被建立。在这篇论文,资源优化被认为由高效地使用网络能力最大化网络产量,在的地方multi-hopfunctionality和空间TDMA(STDMA)存取方案被使用。目的是与给定的交通分布和相应路由选择信息发现最小的框架长度。因为内在的数学问题的复合结构,以前的工作和分析为现实主义的尺寸的网络变得难处理。这个问题通过数学规划途径被处理,线性整数明确的表达为优化网络产量被开发,然后初始问题的类似和图边缘着色问题通过冲突图概念被显示出。一个列产生答案被建议,几改进被做以便系住它的集中。数值结果证明产量的理论限制能高效地为现实主义的尺寸的网络被计算。
简介:Mediumaccesscontrol(MAC)protocolssuchasIEEE802.11areusedinwirelessnetworksforsharingofthewirelessmedium.Therandomnatureoftheprotocoloperationtogetherwiththeinherentdifficultyofmonitoringintheopenposessignificantchallenges.Allnodesareexpectedtocomplywiththeprotocolrules.But,somenodesinordertogaingreaterbenefitsmisbehavebynotcomplyingwiththerules.Onesuchselfishmisbehavioriswaitingforsmallerback-offintervalswhencomparedtotheothernodesinthesamesubnet.Suchselfishmisbehaviorisbeingtackledinthispaper.Adiagnosisschemeandapenaltyschemearebeingproposedforovercomingsuchselfish-misbehavioratMAClayerofmobileadhocnetworkswhichcouldbeextendedtoothertypesofnetworksalso.