電氣測試技術(shù)

電氣測試系統(tǒng)通信技術(shù)OVERVIEWoftheZigBee

1WhatIsLR-WPAN?LowRateWirelessPersonalAreaNetworkSlowdatarate:20~250KbpsShortcoverage:<10mBluetooth(IEEE802.15.1)ToocomplexExpensiveandunappealingforsimplelowcostlowpowerapplicationsIEEE802.15.4ZigBee-wealreadycovered2IEEE802.15.4DriversExtremelylowcostEaseofinstallationReliabledatatransferShortrangeoperationReasonablebatterylife3WhatdoesIEEE802.15.4Consist?CoordinatorCanbeconnectedtootherdevice.PANcoordinator–DesignatedoneinaPANDeviceCanconnecttocoordinator,butnototherdevices.TransfertypeDirectdatatransmissionIndirectdatatransmissionGTSdatatransmission(GuaranteedTimeSlot)BeaconmodeCoordinatorcheckstheeverysub-nodesfrequently.CoordinatorDevices4WhatareIEEE802.15.4’sProperties?FlexibletopologiesStarMulti-hoppeer-to-peertopologies216(64k)devices64-bitIEEEaddress/16-bitshortaddressOperatingintheISMbandsVariousdataratesbutlowrateDifferentdatatransmissionmethodsSecuredatatransferSelf-configuringLowpowerconsumptionLowcost5LR-WPANsareVeryUsefulAutomationandcontrol:Home,factory,warehouseMonitoring:Safety,health,environmentSituationAwarenessandprecisionassetlocation(PAL)MilitaryactionsFirefighteroperationsAutonomousmanifestingReal-timetrackingofinventoryEntertainment:Learninggames,interactivetoys6IEEE802.15.4MACUpperLayersIEEE802.15.4SSCSIEEE802.2LLC,TypeIIEEE802.15.42400MHzPHYIEEE802.15.4868/915MHzPHY802.15.4Architecture7IEEE802.15.4DeviceThePHYLayerisforAccessingSignal8ThePhysicalLayerInterfacewithMACsublayerandphysicalradiochannel.PHYdataservice/PHYmanagementserviceRolesEnergydetection(ED)withinthecurrentchannelLinkqualityindication(LQI)forreceivedpacketsClearchannelassessment(CAA)forcarriersensemultipleaccesswithcollisionavoidance(CSMA-CA)ChannelfrequencyselectionDatatransmissionandreceptionNetworkMACPhysicalTheMACSublayerisforDataTransmitTheMediaAccessControlSublayerInterfacewithPHYlayerandNWKlayer.MACdataservice/MACmanagementserviceRolesGeneratingnetworkbeaconsifthedeviceisacoordinatorSynchronizingtothebeaconsSupportingPANassociationanddisassociationEmployingtheCSMA-CAmechanismforchannelaccessIEEE802.15.4DeviceNetworkMACPhysical9MACOverviewStarandpeer-to-peertopologiesOptionalframestructureAssociationCSMA-CAchannelaccessmechanismPacketvalidationandmessagerejectionOptionalguaranteedtimeslotsGuaranteedpacketdeliveryFacilitateslow-poweroperationSecurity10IEEE802.15.4DeviceClassesFullfunctiondevice(FFD)AnytopologyPANcoordinatorcapableTalkstoanyotherdeviceImplementscompleteprotocolsetReducedfunctiondevice(RFD)Limitedtostartopologyorend-deviceinapeer-to-peernetwork.CannotbecomeaPANcoordinatorVerysimpleimplementationReducedprotocolset11IEEE802.15.4DefinitionsNetworkDevice:AnRFDorFFDimplementationcontaininganIEEE802.15.4mediumaccesscontrolandphysicalinterfacetothewirelessmedium.Coordinator:AnFFDwithnetworkdevicefunctionalitythatprovidescoordinationandotherservicestothenetwork.PANCoordinator:AcoordinatorthatistheprincipalcontrollerofthePAN.AnetworkhasexactlyonePANcoordinator.12Low-PowerOperationDuty-cyclecontrolusingsuperframestructureBeaconorderandsuperframeorderCoordinatorbatterylifeextensionIndirectdatatransmissionDevicesmaysleepforextendedperiodovermultiplebeaconsAllowscontrolofreceiverstatebyhigherlayers13StarTopologyFFDRFDCommunicationsflowMaster/slavePANcoordinator14Peer-PeerTopologyCommunicationsflowPointtopointClustertreeFFDRFDPANcoordinators15CombinedTopologyFFDRFDCommunicationsflowClusteredstars-forexample,clusternodesexistbetweenroomsofahotelandeachroomhasastarnetworkforcontrol.16OptionalFrameStructure15ms*2nwhere0n14GTS3GTS2NetworkbeaconTransmittedbyPANcoordinator.Containsnetworkinformation,framestructureandnotificationofpendingnodemessages.BeaconextensionperiodSpacereservedforbeacongrowthduetopendingnodemessagesContentionperiodAccessbyanynodeusingCSMA-CAGuaranteedTimeSlotReservedfornodesrequiringguaranteedbandwidth[n=0].GTS1SlotBatterylifeextensionContentionAccessPeriodContentionFreePeriod17OptionalFrameStructureSuperframemayhaveinactiveperiod15ms*2BOwhereSOBO1415ms*2SOwhere0SO14SO=SuperframeorderBO=BeaconorderInactivePeriod18GeneralMACFrameFormatFramecontrolfield19BeaconFrameFormat20MACCommandFrameCommandFrameTypesAssociationrequestAssociationresponseDisassociationnotificationDatarequestPANIDconflictnotificationOrphanNotificationBeaconrequestCoordinatorrealignmentGTSrequest21DataFrameFormatAcknowledgementFrameFormat22DataServiceDatatransfertoneighboringdevicesAcknowledgedorunacknowledgedDirectorindirectUsingGTSserviceMaximumdatalength(MSDU)aMaxMACFrameSize

(102bytes)23MACDataPrimitives24DataTransfer

MessageSequenceDiagram25IndirectDataTransfer

MessageSequenceDiagram26ManagementServiceAccesstothePIBAssociation/disassociationGTSallocationMessagependingNodenotificationNetworkscanning/startNetworksynchronization/search27MACManagementPrimitives28Association

MessageSequenceDiagram29Disassociation

MessageSequenceDiagram30DataPolling

MessageSequenceChartNodatapendingatthecoordinator31DataPolling

MessageSequenceChartDatapendingatthecoordinator32PassiveScan33ActiveScan34Orphaning

MessageSequenceDiagram35Inter-frameSpacingForframes≤aMaxSIFSFrameSizeuseshortinter-framespacing(SIFS)Forframes>aMaxSIFSFrameSizeuselonginter-framespacing(LIFS)36SlottedCSMAProcedureUsedinbeaconenablednetworks.37Un-slottedCSMAProcedureUsedinnon-beaconnetworks.38TheNWKLayerisforRoutingTheNetworkLayerInterfacewithMAClayerandapplications.Routingisitsmajorrole.AODV/AODVjrCluster-treeRoutingIntegratedRoutingIEEE802.15.4DeviceNetworkMACPhysical39WhatisAODVandAODVjrAdhocOn-demandDistanceVector(RFC3561)AnalgorithmforroutingacrosswirelessmeshnetworksCapableunicastandmulticastroutingReactiveroutingprotocolEstablishesaroutetoadestinationonlyondemand.c.f.ProactiveInternetprotocolAODVjrSimplifiedversionofAODV40AODV/AODVjrHasBoth-SidesTooStrengthOptimalornear-optimalroutesReducethemessagedeliverylatencyWeaknessRequiremorememoryControloverheadTheinitiallatencySuitablefordeviceswithsufficientmemoriesandfavorlongcommunication41WhatisCluster-treeRouting?Duringthenetworksetuptime,itcanbeformedasatree.ThefirstnodeinaPANwilldesignateitselfasthePANcoordinatorBegintoacceptassociationrequestsfromothernodes.AnynodealreadyinthePANcandeterminewhethertoallowothernodestojoinitWhethertoactasacoordinator,dependingontheavailabilityofitsresourcessuchasmemoryandenergy42ShortAddressAssignmentABECDFGILKJHPANCoordinatorCoordinatorDe