Unit9Network[156]

TextA

IEEE802.15.4[167]

TextB

ZigBee[173]參考譯文IEEE802.15.4

IEEE802.15.4isastandardwhichspecifiesthephysicallayerandmediaaccesscontrolforlow-ratewirelesspersonalareanetworks(LR-WPANs).ItismaintainedbytheIEEE802.15workinggroup.ItisthebasisfortheZigBee,IEEE802.15.4ISA100.11a,WirelessHART,andMiWispecifications,eachofwhichfurtherextendsthestandardbydevelopingtheupperlayerswhicharenotdefinedby802.15.4.Alternatively,itcanbeusedwith6LoWPANandstandardInternetprotocolstobuildaWirelessEmbeddedInternet.(SeeFigure9.1)Figure9.1IEEE802.15.4protocolstack

1.Overview

IEEEstandard802.15.4intendstoofferthefundamentallowernetworklayersofatypeofWirelessPersonalAreaNetwork(WPAN)whichfocusesonlow-cost,low-speedubiquitouscommunicationbetweendevices(incontrastwithother,moreend-userorientedapproaches,suchasWiFi).Theemphasisisonverylowcostcommunicationofnearbydeviceswithlittletonounderlyinginfrastructure,intendingtoexploitthistolowerpowerconsumptionevenmore.

Thebasicframeworkconceivesa10-metercommunicationsrangewithatransferrateof250kbit/s.Tradeoffsarepossibletofavormoreradicallyembeddeddeviceswithevenlowerpowerrequirements,throughthedefinitionofnotone,butseveralphysicallayers.Lowertransferratesof20and40kbit/swereinitiallydefined,withthe100kbit/sratebeingaddedinthecurrentrevision.

Evenlowerratescanbeconsideredwiththeresultingeffectonpowerconsumption.Asalreadymentioned,themainidentifyingfeatureof802.15.4amongWPAN'sistheimportanceofachievingextremelylowmanufacturingandoperationcostsandtechnologicalsimplicity,withoutsacrificingflexibilityorgenerality.

Importantfeaturesincludereal-timesuitabilitybyreservationofguaranteedtimeslots,collisionavoidancethroughCSMA/CAandintegratedsupportforsecurecommunications.Devicesalsoincludepowermanagementfunctionssuchaslinkqualityandenergydetection.

802.15.4-conformantdevicesmayuseoneofthreepossiblefrequencybandsforoperation.

2.Protocolarchitecture

Devicesareconceivedtointeractwitheachotheroveraconceptuallysimplewirelessnetwork.ThedefinitionofthenetworklayersisbasedontheOSImodel;althoughonlythelowerlayersaredefinedinthestandard,interactionwithupperlayersisintended,possiblyusingaIEEE802.2logicallinkcontrolsublayeraccessingtheMACthroughaconvergencesublayer.Implementationsmayrelyonexternaldevicesorbepurelyembedded,self-functioningdevices.

2.1ThePhysicalLayer

ThePhysical

Layer(PHY)ultimatelyprovidesthedatatransmissionservice,aswellastheinterfacetothephysicallayermanagemententity,whichoffersaccesstoeverylayermanagementfunctionandmaintainsadatabaseofinformationonrelatedpersonalareanetworks.Thus,thePHYmanagesthephysicalRFtransceiverandperformschannelselectionandenergyandsignalmanagementfunctions.Itoperatesononeofthreepossibleunlicensedfrequencybands:

·868.0-868.6MHz:Europe,allowsonecommunicationchannel(2003,2006);

·902-928MHz:NorthAmerica,uptotenchannels(2003),extendedtothirty(2006);

·2400-2483.5MHz:worldwideuse,uptosixteenchannels(2003,2006).

Theoriginal2003versionofthestandardspecifiestwophysicallayersbasedonDirectSequenceSpreadSpectrum(DSSS)techniques:oneworkinginthe868/915MHzbandswithtransferratesof20and40kbit/s,andoneinthe2450MHzbandwitharateof250kbit/s.

The2006revisionimprovesthemaximumdataratesofthe868/915MHzbands,bringingthemuptosupport100and250kbit/saswell.Moreover,itgoesontodefinefourphysicallayersdependingonthemodulationmethodused.ThreeofthempreservetheDSSSapproach:inthe868/915MHzbands,usingeitherbinaryoroffsetquadraturephaseshiftkeying(thesecondofwhichisoptional);inthe2450MHzband,usingthelatter.Analternative,optional868/915MHzlayerisdefinedusingacombinationofbinarykeyingandamplitudeshiftkeying(thusbasedonParallel,notSequentialSpreadSpectrum,PSSS).Dynamicswitchingbetweensupported868/915MHzPHYsispossible.

Beyondthesethreebands,theIEEE802.15.4cstudygroupisconsideringthenewlyopened314-316MHz,430-434MHz,and779-787MHzbandsinChina,whiletheIEEE802.15TaskGroup4disdefininganamendmenttotheexistingstandard802.15.4-2006tosupportthenew950MHz-956MHzbandinJapan.FirststandardamendmentsbythesegroupswerereleasedinApril2009.

InAugust2007,IEEE802.15.4awasreleasedexpandingthefourPHYsavailableintheearlier2006versiontosix,includingonePHYusingDirectSequenceUltra-WideBand(UWB)andanotherusingChirpSpreadSpectrum(CSS).TheUWBPHYisallocatedfrequenciesinthreeranges:below1GHz,between3and5GHz,andbetween6and10GHz.TheCSSPHYisallocatedspectruminthe2450MHzband.

InApril2009,IEEE802.15.4candIEEE802.15.4dwerereleasedexpandingtheavailablePHYswithseveraladditionalPHYs:onefor780MHzbandusingO-QPSKorMPSK,anotherfor950MHzusingGFSKorBPSK.

2.2TheMAClayer

TheMediumAccessControl(MAC)enablesthetransmissionofMACframesthroughtheuseofthephysicalchannel.Besidesthedataservice,itoffersamanagementinterfaceanditselfmanagesaccesstothephysicalchannelandnetworkbeaconing.Italsocontrolsframevalidation,guaranteestimeslotsandhandlesnodeassociations.Finally,itoffershookpointsforsecureservices.

2.3Higherlayers

Otherhigher-levellayersandinteroperabilitysublayersarenotdefinedinthestandard.Thereexistspecifications,suchasZigBee,whichbuildonthisstandardtoproposeintegralsolutions.

3.Networkmodel

3.1Nodetypes

Thestandarddefinestwotypesofnetworknode.

ThefirstoneistheFull-FunctionDevice(FFD).Itcanserveasthecoordinatorofapersonalareanetworkjustasitmayfunctionasacommonnode.Itimplementsageneralmodelofcommunicationwhichallowsittotalktoanyotherdevice:itmayalsorelaymessages,inwhichcaseitisdubbedacoordinator.

OntheotherhandthereareReduced-FunctionDevices(RFD).Thesearemeanttobeextremelysimpledeviceswithverymodestresourceandcommunicationrequirements;duetothis,theycanonlycommunicatewithFFD'sandcanneveractascoordinators.

3.2Topologies

NetworkscanbebuiltaseitherPeer-to-Peerorstarnetworks(SeeFigure9.2).However,everynetworkneedsatleastoneFFDtoworkasthecoordinatorofthenetwork.Networksarethusformedbygroupsofdevicesseparatedbysuitabledistances.Eachdevicehasaunique64-bitidentifier,andifsomeconditionsaremetshort16-bitidentifierscanbeusedwithinarestrictedenvironment.Namely,withineachPANdomain,communicationswillprobablyuseshortidentifiers.

Figure9.2IEEE802.15.4starandPeer-to-Peer

Peer-to-Peer(orPoint-to-Point)networkscanformarbitrarypatternsofconnections,andtheirextensionisonlylimitedbythedistancebetweeneachpairofnodes.Theyaremeanttoserveasthebasisforadhocnetworkscapableofperformingself-managementandorganization.Sincethestandarddoesnotdefineanetworklayer,routingisnotdirectlysupported,butsuchanadditionallayercanaddsupportformultihopcommunications.Furthertopologicalrestrictionsmaybeadded;thestandardmentionstheclustertree(SeeFigure9.3)asastructurewhichexploitsthefactthatanRFDmayonlybeassociatedwithoneFFDatatimetoformanetworkwhereRFD'sareexclusivelyleavesofatree,andmostofthenodesareFFD's.Thestructurecanbeextendedasagenericmeshnetworkwhosenodesareclustertreenetworkswithalocalcoordinatorforeachcluster,inadditiontotheglobalcoordinator.

Amorestructuredstarpatternisalsosupported,wherethecoordinatorofthenetworkwillnecessarilybethecentralnode.SuchanetworkcanoriginatewhenanFFDdecidestocreateitsownPANanddeclareitselfitscoordinator,afterchoosingauniquePANidentifier.Afterthat,otherdevicescanjointhenetwork,whichisfullyindependentfromallotherstarnetworks.

Figure9.3IEEE802.15.4clustertree

4.Datatransportarchitecture

Framesarethebasicunitofdatatransport,ofwhichtherearefourfundamentaltypes(data,acknowledgment,beaconandMACcommandframes),whichprovideareasonabletradeoffbetweensimplicityandrobustness.Additionally,asuperframestructure,definedbythecoordinator,maybeused,inwhichcasetwobeaconsactasitslimitsandprovidesynchronizationtootherdevicesaswellasconfigurationinformation.Asuperframeconsistsofsixteenequal-lengthslots,whichcanbefurtherdividedintoanactivepartandaninactivepart,duringwhichthecoordinatormayenterpowersavingmode,notneedingtocontrolitsnetwork.

Withinsuperframescontentionoccursbetweentheirlimits,andisresolvedbyCSMA/CA.Everytransmissionmustendbeforethearrivalofthesecondbeacon.Asmentionedbefore,applicationswithwell-definedbandwidthneedscanuseuptosevendomainsofoneormorecontentionlessguaranteedtimeslots,trailingattheendofthesuperframe.Thefirstpartofthesuperframemustbesufficienttogiveservicetothenetworkstructureanditsdevices.Superframesaretypicallyutilizedwithinthecontextoflow-latencydevices,whoseassociationsmustbekeptevenifinactiveforlongperiodsoftime.

Datatransferstothecoordinatorrequireabeaconsynchronizationphase,ifapplicable,followedbyCSMA/CAtransmission(bymeansofslotsifsuperframesareinuse);acknowledgmentisoptional.Datatransfersfromthecoordinatorusuallyfollowdevicerequests:ifbeaconsareinuse,theseareusedtosignalrequests;thecoordinatoracknowledgestherequestandthensendsthedatainpacketswhichareacknowledgedbythedevice.Thesameisdonewhensuperframesarenotinuse,onlyinthiscasetherearenobeaconstokeeptrackofpendingmessages.

Point-to-PointnetworksmayeitheruseunslottedCSMA/CAorsynchronizationmechanisms;inthiscase,communicationbetweenanytwodevicesispossible,whereasin"structured"modesoneofthedevicesmustbethenetworkcoordinator.

Ingeneral,allimplementedproceduresfollowatypicalrequest-confirm/indication-responseclassification.

5.Reliabilityandsecurity

ThephysicalmediumisaccessedthroughaCSMA/CAprotocol.Networkswhicharenotusingbeaconingmechanismsutilizeanunslottedvariationwhichisbasedonthelisteningofthemedium,leveragedbyarandomexponentialbackoffalgorithm;acknowledgmentsdonotadheretothisdiscipline.Commondatatransmissionutilizesunallocatedslotswhenbeaconingisinuse;again,confirmationsdonotfollowthesameprocess.

Confirmationmessagesmaybeoptionalundercertaincircumstances.Whateverthecase,ifadeviceisunabletoprocessaframeatagiventime,itsimplydoesnotconfirmitsreception:timeout-basedretransmissioncanbeperformedanumberoftimes,followingafterthatadecisionofwhethertoabortorkeeptrying.

Becausethepredictedenvironmentofthesedevicesdemandsmaximizationofbatterylife,theprotocolstendtofavorthemethodswhichleadtoit,implementingperiodicchecksforpendingmessages,thefrequencyofwhichdependsonapplicationneeds.

Regardingsecurecommunications,theMACsublayeroffersfacilitieswhichcanbeharnessedbyupperlayerstoachievethedesiredlevelofsecurity.Higher-layerprocessesmayspecifykeystoperformsymmetriccryptographytoprotectthepayloadandrestrictittoagroupofdevicesorjustaPoint-to-Pointlink;thesegroupsofdevicescanbespecifiedinaccesscontrollists.Furthermore,MACcomputesfreshnesschecksbetweensuccessivereceptionstoensurethatpresumablyoldframes,ordatawhichisnolongerconsideredvalid,doesnottranscendtohigherlayers.

Inadditiontothissecuremode,thereisanother,insecureMACmode,whichallowsaccesscontrollistsmerelyasameanstodecideontheacceptanceofframesaccordingtotheir(presumed)source.

ZigBeeisaspecificationforasuiteofhighlevelcommunicationprotocolsusingsmall,low-powerdigitalradiosbasedonanIEEE802standardforpersonalareanetworks.Applicationsincludewirelesslightswitches,electricalmeterswithin-home-displays,ZigBeeandotherconsumerandindustrialequipmentthatrequiresshort-rangewirelesstransferofdataatrelativelylowrates.ThetechnologydefinedbytheZigBeespecificationisintendedtobesimplerandlessexpensivethanotherWPANs,suchasBluetooth.ZigBeeistargetedatRadio-Frequency(RF)applicationsthatrequirealowdatarate,longbatterylife,andsecurenetworking.ZigBeehasadefinedrateof250kbpsbestsuitedforperiodicorintermittentdataorasinglesignaltransmissionfromasensororinputdevice.(SeeFigure9.4)

Thenamereferstothewaggledanceofhoneybeesaftertheirreturntothebeehive.

The€

1coin,shownforsizereference,

isabout23mm(0.9inch)indiameter.Firgure9.4ZigBeemodule.

1.Technicaloverview

ZigBeeisalow-cost,low-power,wirelessmeshnetworkstandard.Thelowcostallowsthetechnologytobewidelydeployedinwirelesscontrolandmonitoringapplications.Lowpower-usageallowslongerlifewithsmallerbatteries.Meshnetworkingprovideshighreliabilityandmoreextensiverange.ThetechnologyisintendedtobesimplerandlessexpensivethanotherWPANssuchasBluetooth.ZigBeechipvendorstypicallysellintegratedradiosandmicrocontrollerswithbetween60KBand256KBflashmemory.

ZigBeeoperatesintheIndustrial,ScientificandMedical(ISM)radiobands;868MHzinEurope,915MHzintheUSAandAustralia,and2.4GHzinmostjurisdictionsworldwide.Datatransmissionratesvaryfrom20to250kilobits/second.

TheZigBeenetworklayernativelysupportsbothstarandtreetypicalnetworks,andgenericmeshnetworks.Everynetworkmusthaveonecoordinatordevice,taskedwithitscreation,thecontrolofitsparametersandbasicmaintenance.Withinstarnetworks,thecoordinatormustbethecentralnode.BothtreesandmeshesallowstheuseofZigBeerouterstoextendcommunicationatthenetworklevel.

ZigBeebuildsuponthephysicallayerandmediumaccesscontroldefinedinIEEEstandard802.15.4(2003version)forlow-rateWPAN's.Thespecificationgoesontocompletethestandardbyaddingfourmaincomponents:networklayer,applicationlayer,ZigBeeDeviceObjects(ZDO's)andmanufacturer-definedapplicationobjectswhichallowforcustomizationandfavortotalintegration.(SeeFigure9.5)

Besidesaddingtwohigh-levelnetworklayerstotheunderlyingstructure,themostsignificantimprovementistheintroductionofZDO's.Theseareresponsibleforanumberoftasks,whichincludekeepingofdeviceroles,managementofrequeststojoinanetwork,devicediscoveryandsecurity.

Figure9.5ZigBeeprotocolstack

ZigBeeisnotintendedtosupportpowerlinenetworkingbuttointerfacewithitatleastforsmartmeteringandsmartappliancepurposes.

BecauseZigBeenodescangofromsleeptoactivemodein30msecorless,thelatencycanbelowanddevicescanberesponsive,particularlycomparedtoBluetoothwake-updelays,whicharetypicallyaroundthreeseconds.BecauseZigBeenodescansleepmostofthetime,averagepowerconsumptioncanbelow,resultinginlongbatterylife.

2.Uses

ZigBeeprotocolsareintendedforembeddedapplicationsrequiringlowdataratesandlowpowerconsumption.Theresultingnetworkwilluseverysmallamountsofpower—individualdevicesmusthaveabatterylifeofatleasttwoyearstopassZigBeecertification.

Typicalapplicationareasinclude:

·HomeEntertainmentandControl—Homeautomation,smartlighting,advancedtemperaturecontrol,safetyandsecurity,moviesandmusic;

·WirelessSensorNetworks'—StartingwithindividualsensorslikeTelosb/TmoteandIrisfromMemsic;

·Industrialcontrol;

·Embeddedsensing;

·Medicaldatacollection;

·Smokeandintruderwarning;

·Buildingautomation.

3.Devicetypes

TherearethreedifferenttypesofZigBeedevices:

·ZigBeeCoordinator(ZC):Themostcapabledevice,thecoordinatorformstherootofthenetworktreeandmightbridgetoothernetworks.ThereisexactlyoneZigBeeCoordinatorineachnetworksinceitisthedevicethatstartedthenetworkoriginally.Itisabletostoreinformationaboutthenetwork,includingactingastheTrustCenter&repositoryforsecuritykeys.

·ZigBeeRouter(ZR):Aswellasrunninganapplicationfunction,aroutercanactasanintermediaterouter,passingondatafromotherdevices.

·ZigBeeEndDevice(ZED):Containsjustenoughfunctionalitytotalktotheparentnode(eitherthecoordinatororarouter);itcannotrelaydatafromotherdevices.Thisrelationshipallowsthenodetobeasleepasignificantamountofthetimetherebygivinglongbatterylife.AZEDrequirestheleastamountofmemory,andthereforecanbelessexpensivetomanufacturethanaZRorZC.

4.Protocols

Theprotocolsbuildonrecentalgorithmicresearch(Ad-hocOn-demandDistanceVector,neuRFon)toautomaticallyconstructalow-speedad-hocnetworkofnodes.Inmostlargenetworkinstances,thenetworkwillbeaclusterofclusters.Itcanalsoformameshorasinglecluster.ThecurrentZigBeeprotocolssupportbeaconandnon-beaconenablednetworks.

Innon-beacon-enablednetworks,anunslottedCSMA/CAchannelaccessmechanismisused.Inthistypeofnetwork,ZigBeeRouterstypicallyhavetheirreceiverscontinuouslyactive,requiringamorerobustpowersupply.However,thisallowsforheterogeneousnetworksinwhichsomedevicesreceivecontinuously,whileothersonlytransmitwhenanexternalstimulusisdetected.Thetypicalexampleofaheterogeneousnetworkisawirelesslightswitch:TheZigBeenodeatthelampmayreceiveconstantly,sinceitisconnectedtothemainssupply,whileabattery-poweredlightswitchwouldremainasleepuntiltheswitchisthrown.Theswitchthenwakesup,sendsacommandtothelamp,receivesanacknowledgment,andreturnstosleep.InsuchanetworkthelampnodewillbeatleastaZigBeeRouter,ifnottheZigBeeCoordinator;theswitchnodeistypicallyaZigBeeEndDevice.

Inbeacon-enablednetworks,thespecialnetworknodescalledZigBeeRouterstransmitperiodicbeaconstoconfirmtheirpresencetoothernetworknodes.Nodesmaysleepbetweenbeacons,thusloweringtheirdutycycleandextendingtheirbatterylife.Beaconintervalsdependondatarate;theymayrangefrom15.36millisecondsto251.65824secondsat250kbit/s,from24millisecondsto393.216secondsat40kbit/sandfrom48millisecondsto786.432secondsat20kbit/s.However,lowdutycycleoperationwithlongbeaconintervalsrequiresprecisetiming,whichcanconflictwiththeneedforlowproductcost.

Ingeneral,theZigBeeprotocolsminimizethetimetheradioison,soastoreducepoweruse.Inbeaconingnetworks,nodesonlyneedtobeactivewhileabeaconisbeingtransmitted.Innon-beacon-enablednetworks,powerconsumptionisdecidedlyasymmetrical:somedevicesarealwaysactive,whileothersspendmostoftheirtimesleeping.

ExceptfortheSmartEnergyProfile2.0,ZigBeedevicesarerequiredtoconformtotheIEEE802.15.4-2003Low-RateWirelessPersonalAreaNetwork(LR-WPAN)standard.Thestandardspecifiesthelowerprotocollayers—thePhysicalLayer(PHY),andtheMediaAccessControlportionoftheDataLinkLayer(DLL).Thebasicchannelaccessmodeis"CarrierSense,MultipleAccess/CollisionAvoidance"(CSMA/CA).Thatis,thenodestalkinthesamewaythatpeopleconverse;theybrieflychecktoseethatnooneistalkingbeforetheystart.TherearethreenotableexceptionstotheuseofCSMA.Beaconsaresentonafixedtimingschedule,anddonotuseCSMA.MessageacknowledgmentsalsodonotuseCSMA.Finally,devicesinBeaconOrientednetworksthathavelowlatencyreal-timerequirementsmayalsouseGuaranteedTimeSlots(GTS),whichbydefinitiondonotuseCSMA.

IEEE802.15.4是一個(gè)標(biāo)準(zhǔn)，它為低速率無(wú)線個(gè)人局域網(wǎng)(LR-WPANs)中物理層和介質(zhì)訪問(wèn)控制提供規(guī)范，它由IEEE802.15工作組維護(hù)。它是ZigBee、ISA100.11a、WirelessHART以及MiWi規(guī)范的基礎(chǔ)，這些規(guī)范都進(jìn)一步擴(kuò)展了該標(biāo)準(zhǔn)，方法是開(kāi)發(fā)802.15.4沒(méi)有定義的上層。另外一個(gè)選擇是將IEEE802.15.4和6LoWPAN以及標(biāo)準(zhǔn)的因特網(wǎng)協(xié)議一起使用，建立一個(gè)無(wú)線嵌入式因特網(wǎng)。IEEE802.15.4

1.概論

IEEE802.15.4標(biāo)準(zhǔn)打算為無(wú)線個(gè)人局域網(wǎng)(WPAN)提供基礎(chǔ)較低的網(wǎng)絡(luò)層。WPAN著重在低成本、低速設(shè)備之間廣泛通訊(與之相對(duì)的是其他更面向終端用戶(hù)的方法，如WiFi)，重點(diǎn)是近距離的、有很少或無(wú)底層基礎(chǔ)設(shè)施的設(shè)備之間的低成本通訊，且打算用它來(lái)降低功耗。

基本框架設(shè)想在10米的通信范圍內(nèi)，傳輸率為250kbit/s，也可以折衷傳輸率來(lái)支持更多功耗更低的嵌入設(shè)備，方法是定義多個(gè)而不是一個(gè)物理層。初期定義的傳輸率更低，在20kbit/s到40kbit/s之間，最近的修訂版中的傳輸率已經(jīng)增加了100kbit/s。使用低傳輸率主要是為了降低功耗。如上所述，WPAN中802.15.4的主要標(biāo)志性特點(diǎn)在于制造和運(yùn)行成本低，而且技術(shù)簡(jiǎn)單，不會(huì)犧牲靈活性和通用性。

實(shí)時(shí)適應(yīng)性也是IEEE802.15.4的主要特色，方法是保留確定的時(shí)隙、通過(guò)CSMS/CA避免沖突并完全支持安全通信。802.15.4設(shè)備也包括電源管理功能，如鏈接質(zhì)量和電能檢查。

802.15.4兼容設(shè)備使用三種頻段中的一種來(lái)運(yùn)行。

2.協(xié)議體系

802.15.4設(shè)備可以通過(guò)概念簡(jiǎn)單的無(wú)線網(wǎng)絡(luò)實(shí)現(xiàn)相互結(jié)合。網(wǎng)絡(luò)層的定義基于OSI模型；雖然在該標(biāo)準(zhǔn)中只定義了低層，但如果打算與高層交互的話，則可使用IEEE802.2邏輯鏈路控制子層并通過(guò)匯聚子層來(lái)訪問(wèn)MAC。此訪問(wèn)可依賴(lài)外部設(shè)備或者純嵌入的、自運(yùn)行設(shè)備來(lái)實(shí)現(xiàn)。

2.1物理層

物理層(PHY)總的來(lái)說(shuō)可提供數(shù)據(jù)傳輸服務(wù)，也可以作為物理層管理實(shí)體的接口，管理每層并維護(hù)相關(guān)個(gè)人局域網(wǎng)的信息庫(kù)。因此，PHY管理物理RF收發(fā)器并選擇通道、管理能源和信號(hào)。它運(yùn)行在下面三個(gè)可能未經(jīng)許可的波段之一：

868.0MHz～868.6MHz：歐洲，允許一個(gè)信道(2003,2006)；

902MHz～928MHz：北美，高達(dá)10個(gè)通道(2003)，已擴(kuò)展到30個(gè)(2006)；

2400MHz～2483.5MHz：全球使用，高達(dá)60通道(2003,2006)。

該標(biāo)準(zhǔn)的2003年版本原來(lái)指定了基于直接序列擴(kuò)頻(DSSS)技術(shù)的兩個(gè)物理層：一個(gè)工作在傳輸率為20kbit/s～40kbit/s的868/915MHz波段，另一個(gè)工作在傳輸率為250kbit/s的2450MHz波段。

2006年版本增大了868/915MHz波段的數(shù)據(jù)傳輸率，上調(diào)到支持100kbit/s和250kbit/s的傳輸率。更重要的是，它進(jìn)一步定義了基于所使用的調(diào)制模式的四個(gè)物理層。其中三個(gè)層繼續(xù)使用DSSS方法：在868/915MHz波段，使用二相或偏移四相移相鍵控(其中第二個(gè)是一個(gè)備選項(xiàng))；在2450MHz波段，使用偏移四項(xiàng)移相鍵控。另外的選擇是，用二相鍵控和幅移鍵控組合定義868/915MHz層(因此這就基于平行，而不是序列擴(kuò)展頻譜，PSSS)。在支持的868/915MHzPHY之間動(dòng)態(tài)切換是可能的。

除了這三個(gè)波段外，IEEE802.15.4c研究組正在考慮使用最新在中國(guó)開(kāi)放的314MHz～316MHz、430MHz～434MHz以及779MHz～787MHz波段，而IEEE802.15TaskGroup4d正在改進(jìn)現(xiàn)有的802.15.4-2006標(biāo)準(zhǔn)以便支持日本新的950MHz～956MHz