低功耗蓝牙通信技术及其与轻量级IPv6

22Apr,2012Atalkat‘WirelessConnectivityTechnologiesforEmbeddedSystems’organizedbyEmbeddedSystemsAssociation@BeihangUniversityCanfengChen,PhDNokiaResearchCenter,RadioSystemsLabBluetoothLowEnergyanditsConvergencewithLightweightIPv61Agenda•BluetoothLowEnergy&Bluetoothroadmap•BluetoothLowEnergystack&chips&products•LightweightIPv6forBluetoothLowEnergy2Agenda•BluetoothLowEnergy&Bluetoothroadmap•BluetoothLowEnergystack&chips&products•LightweightIPv6forBluetoothLowEnergy3BluetoothCoreSpecificationsVersionFeatureReleasedRFDataRateBluetoothv1.1IEEE802.15.120012.4GHz1MbpsBluetoothv1.2PersonalAreaNetwork20032.4GHz1MbpsBluetoothv2.0+EDREnhancedDataRate20042.4GHz3MbpsBluetoothv2.1+EDRSimpleSecurePairing20072.4GHz3MbpsBluetoothv3.0+HSHighSpeed2009~5GHz24MbpsBluetoothv4.0Ultra-LowPower20102.4GHz1Mbps4BluetoothLowEnergyHistory•NokiaNRCmadeaproposalin2001•BT_LEE(BluetoothLowerEnergyEnd)•WibreeForumwasformedin2006•BT-SIGrenamedittoUltraLowPower(ULP)in2007•In2008BT-SIGannouncedBluetoothLowEnergyasthemarketingnameforULP•BT-SIGreleasedBluetoothSpecv4,incl.BLEinJuly2010•October2011,BT-SIGrenamedBLEasBluetoothSmart(singlemode),andBluetoothSmartReady(dualmode)5BluetoothLowEnergy–introducedwithBluetoothv4.0•Bluetoothlowenergytechnologyisaglobalstandard,verylowpowerwirelesstechnology•BluetoothlowenergytechnologyenablesdeviceswithcoincellbatteriestobewirelesslyconnectedtostandardBluetoothenableddevices6BR/EDRandLEcomparison7Principlesofultralowpoweroperation•Lowdutycycle,shortpackagesandhighonairdatarate•Connectionintervalsfrom3msto4s+•Shortdatapackets–upto31bytespayload•1Mbpson-airdatarate•Systemspendsmosttimeinsleepmode•RFisononlyasmallfractionofthetime•Fastconnectiontime•Devicescanconnectin3ms•Allowsforfastconnection,senddataandthendisconnect•Systemcanspendmostofthetimeindeepsleep•Lowpeakpower•UserelaxedRFparametersforGFSKmodulation81.Lowerstandbytime•Bluetoothlowenergytechnologyusesonly3advertisingchannels•Bluetoothtechnologyuses16to32channels•RFisonfor0.6to1.2msinsteadof22.5ms•Idlecurrentisdominatedbydeepsleepcurrent•Sensortypeofapplicationssenddatalessoften(0.5sto4sintervals)•RFcurrentisnegligibleduetolowdutycycles•Protocolsoptimizedforthiscommunicationmodel92.Fasterconnection•InBluetoothlowenergytechnology–adevicethatisadvertisingisabletoconnecttoascanningdevice•Thedevicescanconnectin3ms•InBluetoothtechnologyalinklevelconnectioncantakeupto100ms•InBluetoothtechnologyanL2CAPconnectioncantakesignificantlylonger103.Lowerpeakpower•BluetoothlowenergytechnologyusesrelaxedRFparameters•GFSKmodulationindexincreased•Allowingbetterrange/robustness•BLEusesrelaxedRFparameters•GFSKmodulation•2MHzbandwidth•BT=0.5•BTusesstrictRFparameters•GFSKmodulation(EDRusesπ/4QPSK,π/8PSK)•1MHzbandwidth•BT=0.35•Packetlengthrestricted•TogethertoGFSKgiveslowestcomplexitytransmitter/receiver•Givesyoulowerpeakpower•THISGIVESYOUCOINCELLOPERATION11BluetoothLowEnergyisbornforSensorapplications•Sumup:Howtoachieveultimatelowpower?•Lowerstandbytime(i.e.lowerdutycycle)•Fasterconnection(i.e.abletosenddataquicker)•Lowerpeakpower(i.e.abletobeusedwithcoincellbattery)•Sensorsaretheidealapplication–transmittingsmallamountsofdiscretedata12LowEnergydesignedforEmbeddedSensorApplications•Lowenergyconsumptionmeansthatthebatterywillworkforyears–thelifetimeofthedevice•Withnoneedforreplacement,thebatterycanbeencapsulatedintheproduct,permittingpreviouslyimpossibleapplications13LowEnergydesignedforInternetofThingsthruGateway•Enableslow-powersensoraccessoriestowirelesslyconnecttogatewaydevices,andtherebytotheInternet•RemoteUIandappdownloadablefromWeb,reducethecomplexityofsensordevices14Agenda•BluetoothLowEnergy&Bluetoothroadmap•BluetoothLowEnergystack&chips&products•LightweightIPv6forBluetoothLowEnergy15BLEstack16Dual-modeandsingle-mode17Physicallayer–twotypesofchannels•2.4GHzISMBandTransceiver•Dividedinto40RFChannels•2MHzChannelSpacing•AdvertisingChannels•Usedtobroadcastdata•Connectable•Discoverable•3FIXEDChannels•DataChannels•Usedtosendapplicationdata•AdaptivelyFrequencyHopped•37DynamicChannels18Physicallayer–advertisingavoidWiFi19LinkLayer–states20ScanningAdvertisingInitiatingConnectingStandbyLinklayer–packetformat•Allpacketshavesamestructure•Preamble–01010101or10101010•AccessAddress–correlated32bitsequence•Payload–actualdata•CRC–24bitCRCforrobustbiterrordetection•CRCcalculatedoverPayload21PreambleAccessAddressPayloadCRC1octet4octets2to39octets3octetsBLEnewfunctionalities•TherearethreemajorcomponentsofLEbaselinecorefunctionality•GAP–GeneralAccessProtocol(EstablishingConnections,AdvertisingServices)•GATT–GenericAttributeTransport(dataexchangebetweenhigh-levelservices)•SM–SecurityManager(Pairing/Bonding/AuthenticationandLinkSecurity/Encryption)22GAP•ExtensionofexistingBR/EDRGAP•Definesprofilerolesthatthedevicescantake•Broadcaster,Observer•Peripheral,Central•Definesthestandardwaysfordevicestoconnect•Discoverable,Connectable,Bonding23Fourdifferentprofileroles•Broadcaster,Observer,Peripheral,Central24LinklayerstatemachineforBroadcasterandObserver25LinklayerstatemachineforPeripheralandCent