简介:Militarytacticalnetworkisoneofthemostimportantapplicationsofadhocnetwork.Currentlytheexistingroutingprotocolsareputforwardbasedonthesimpleanduniversalnetworkmodelwhichhastheabilityofmulti-hoproutingbutcannotworkefficientlyinthespecialmilitaryapplications.Thenarrowbandwidthandlimitedenergyofthewirelessnetworkmakegeneralroutingprotocolsseemtobemoreredundant.Inordertosatisfymilitaryneedsproperly,thislettermakesadetailedanalysisofphysicalnodesandtrafficdistributioninmilitarynetwork,usescross-layerdesignconceptforreference,combinestrafficcharacteristicofapplicationlayerwithroutingprotocoldesign.Itcategorizedroutingproblemascrucialroutesandnon-crucialrouteswhichadoptedseparatemaintenancemethods.Itnotonlyrealizesbasictransmissionfunctionbutalsoworksefficiently.Itisquitefitformilitaryapplication.
简介:AMinimizingIntermediateMulticastRoutingprotocol(MIMR)isproposedfordynamicmulti-hopadhocnetworks.InMIMR,multicastsessionsarecreatedandreleasedonlybysourcenodes.Ineachmulticastsessionprocess,thesourcenodekeepsalistofintermediatenodesanddestinations,whichisencapsulatedintothepacketheaderwhenthesourcenodesendsamulticastpacket.Nodesreceivingmulticastpacketsdecidetoacceptorforwardthepacketaccordingtothelist.Dependingontopologymatrixmaintainedbyunicastrouting,theshortestvirtualhierarchyroutingtreeiscon-structedbyimprovedDijkstraalgorithm.MIMRcanachievetheminimumnumberofintermediatenodes,whicharecomputedthroughthetree.Nocontrolpacketistransmittedintheprocessofmul-ticastsession.Loadofthenetworkislargelydecreased.ExperimentalresultshowsthatMIMRisflexibleandrobustfordynamicadhocnetworks.
简介:针对无线传感器网络无需测距的DV—Hop定位算法中存在误差率较大的问题,本文从两个方面对其进行了改进:引入平均误差修正信标节点间的平均每跳距离;引入权重因子计算未知节点坐标.仿真结果表明,改进算法比传统DV—Hop算法误差率更低,能更好地应用于实际场景.
简介:Asthesystemperformanceisobviouslyimprovedbyintroducingtheconceptofrelayintothetraditionalorthogonalfrequencydivisionmultipleaccess(OFDMA)systems,resourceschedulinginrelay-enhancedOFDMAsystemsisworthyofbeingstudiedcarefully.Tosolvetheoptimizationproblemofachievingthemaximumthroughputwhilesatisfyingthequalityofservice(QoS)andguaranteeingthefairnessofusers,anovelresourceschedulingschemewithQoSsupportforthedownlinkoftwo-hoprelay-enhancedOFDMAsystemsisproposed.Theproposedscheme,whichisconsideredbothinthefirsttimesub-slotbetweendirectlinkusersandrelaystations,andthesecondtimesub-slotamongrelaylinkusers,takesQoSsupportintoconsideration,aswellasthesystemthroughputandthefairnessforusers.Simulationresultsshowthattheproposedschemehasgoodperformanceinmaximizingsystemthroughputandguaranteeingtheperformanceintheservicedelayandthedatalossrate.
简介:1.IntroductionDailyphysicalactivity(PA)participationiscrucialtothehealthandwell-beingofyoungchildren.Alongwithtotalphysicalactivity(TPA;all-intensity),moderate-to-vigorousphysicalactivity(MVPA),orenergeticplay,isassociatedwithgreaterhealthbenefits,particularlyforpreschoolers(3-4years),includingbutnotlimitedtoimprovedboneandskeletalpropertiesandcognitiveandpsychosocialhealth.1Centeredonthis,bothCanadaandAustraliahaverecentlyestablished24-HourMovementGuidelinesfortheEarlyYears,recommendingthat.