Zigbee无线传感器网络英文文献.docx

Zigbee无线传感器网络英文文献.docx

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Zigbee无线传感器网络英文文献

ZigbeeWirelessSensorNetworkinEnvironmentalMonitoring

Applications

I.ZIGBEETECHNOLOGY

ZigbeeisawirelessstandardbasedonIEEE02.15.4thatwasdevelopedtoaddresstheuniqueneedsofmostwirelesssensingandcontrolapplications.Technologyislowcost,lowpower,alowdatarate,highlyreliable,highlysecurewirelessnetworkingprotocoltargetedtowardsautomationandremotecontrolapplications.It'depictstwokeyperformaneecharacteristics-wirelessradiorangeanddatatransmissionrateofthewirelessspectrum.ComparingtootherwirelessnetworkingprotocolssuchasBluetooth,Wi-Fi,UWBandsoon,showsexcellenttransmissionabilityinlowertransmissionrateandhighlycapacityofnetwork.

A.ZigbeeFramework

Frameworkismadeupofasetofblockscalledlayers.Eachlayerperformsaspecificsetofservicesforthelayerabove.AsshowninFig.1.TheIEEE802.15.4standarddefinesthetwolowerlayers:

thephysical（PHY）layerandthemediumaccesscontrol（MAC）layer.

TheAlliancebuildsonthisfoundationbyprovidingthenetworkandsecuritylayerandthe

Application

frameworkfortheapplicationlayer.

ApplictatianZlgSeeStack

Hardware

Fig.1Framework

TheIEEE802.15.4hastwoPHYlayersthatoperateintwoseparatefrequencyranges:

868/915MHzand2.4GHz.Moreover,MACsub-layercontrolsaccesstotheradiochannelusingaCSMA-CAmechanism.Itsresponsibilitiesmayalsoincludetransmittingbeaconframes,synchronization,andprovidingareliabletransmissionmechanism.

B.Zigbee'sTopology

Thenetworklayersupportsstar,tree,andmeshtopologies,asshowninFig2.Inastartopology,thenetworkiscontrolledbyonesingledevicecalledcoordinator.Thecoordinator

isresponsibleforinitiatingandmaintainingthedevicesonthenetwork.Allotherdevices,knownasenddevices,directlycommunicatewiththecoordinator.Inmeshandtreetopologies,thecoordinatorisresponsibleforstartingthenetworkandforchoosingcertainkeynetworkparameters,butthenetworkmaybeextendedthroughtheuseofrouters.Intreenetworks,routersmovedataandcontrolmessagesthroughthenetworkusingahierarchical

routingstrategy.Meshnetworksallowfullpeer-to-peercommunication.

Fig.2Meshtopologies

Fig.3isanetworkmodel,itshowsthatsupportsbothsingle-hopstartopologyconstructedwithonecoordinatorinthecenterandtheenddevices,andmeshtopology.Inthenetwork,theintelligentnodesarecomposedbyFullFunctionDevice（FFD）andReducedFunctionDevice（RFD）.OnlytheFFNdefinesthefullfunctionalityandcanbecomeanetworkcoordinator.Coordinatormanagesthenetwork,itistosaythatcoordinatorcanstartanetworkandallowotherdevicestojoinorleaveit.Moreover,itcanprovidebindingand

address-tableservices,andsavemessagesuntiltheycanbedelivered.

Fig.3Zigbeenetworkmodel

II.THEGREENHOUSEENVIRONMENTALMONITORING

SYSTEMDESIGN

Traditionalagricultureonlyusemachineryandequipmentwhichisolatingandnocommunicatingability.Andfarmershavetomonitorcropsgrowthbythemselves.Evenifsomepeopleuseelectricaldevices,butmostofthemwererestrictedtosimplecommunicationbetweencontrolcomputerandenddeviceslikesensorsinsteadofwireconnection,whichcouldn'btestrictlydefinedaswirelesssensornetwork.Therefore,bythroughusingsensornetworksand,agriculturecouldbecomemoreautomation,morenetworkingandsmarter.

Inthisproject,weshoulddeployfivekindsofsensorsinthegreenhousebasement.Bythroughthesedeployedsensors,theparameterssuchastemperatureinthegreenhouse,soiltemperature,dewpoint,humidityandlightintensitycanbedetectedrealtime.Itiskeytocollectdifferentparametersfromallkindsofsensors.Andinthegreenhouse,monitoringthevegetablesgrowingconditionsisthetopissue.Therefore,longerbatterylifeandlowerdatarateandlesscomplexityareveryimportant.Fromtheintroductionaboutabove,weknowthatmeettherequirementsforreliability,security,lowcostsandlowpower.

A.SystemOverview

TheoverviewofGreenhouseenvironmentalmonitoringsystem,whichismadeupbyonesinknode（coordinator）,manysensornodes,workstationanddatabase.Motenodeandsensornodetogethercomposedofeachcollectingnode.Whensensorscollectparametersrealtime,suchastemperatureinthegreenhouse,soiltemperature,dewpoint,humidityandlightintensity,thesedatawillbeofferedtoA/Dconverter,thenbythroughquantizingandencodingbecomethedigitalsignalthatisabletotransmitbywirelesssensorcommunicatingnode.Eachwirelesssensorcommunicatingnodehasabilityoftransmitting,receivingfunction.

InthisWSN,sensornodesdeployedinthegreenhouse,whichcancollectrealtimedataandtransmitdatatosinknode（Coordinator）bythewayofmulti-hop.Sinknodecompletethetaskofdataanalysisanddatastorage.Meanwhile,sinknodeisconnectedwithGPRS/CDMAcanprovideremotecontrolanddatadownloadservice.Inthemonitoringandcontrollingroom,byrunninggreenhousemanagementsoftware,thesinknodecanperiodicallyreceivesthedatafromthewirelesssensornodesanddisplaysthemonmonitors.

B.NodeHardwareDesign

SensornodesarethebasicunitsofWSN.Thehardwareplatformismadeupsensornodescloselyrelatedtothespecificapplicationrequirements.Therefore,themostimportantworkisthenodesdesignwhichcanperfectimplementthefunctionofdetectingandtransmissionasaWSNnode,andperformitstechnologycharacteristics.Fig.4showstheuniversalstructureoftheWSNnodes.Powermoduleprovidesthenecessaryenergyforthesensornodes.Datacollectionmoduleisusedtoreceiveandconvertsignalsofsensors.Dataprocessingandcontrolmodule'functionsarenodedevicecontrol,taskscheduling,and

energycomputingandsoon.Communicationmoduleisusedtosenddatabetweennodesand

frequencychosenandsoon.

Fig.4Universalstructureofthewsnnodes

Inthedatatransferunit,themoduleisembeddedtomatchtheMAClayerandtheNETlayeroftheprotocol.WechooseCC2430astheprotocolchips,whichintegratedtheCPU,RFtransceiver,netprotocolandtheRAMtogether.CC2430usesan8bitMCU（8051）,andhas128KBprogrammableflashmemoryand8KBRAM.ItalsoincludesA/Dconverter,someTimers,AES128Coprocessor,WatchdogTimer,32KcrystalSleepmodeTimer,PoweronReset,BrownoutDetectionand21I/Os.Basedonthechips,manymodulesfortheprotocolareprovided.Andthetransferunitcouldbeeasilydesignedbasedonthemodules.

Asanexampleofasensorenddeviceintegratedtemperature,humidityandlight,the

designisshowninFig.5.

Fig.5Thehardwaredesignofasensornode

TheSHT11isasinglechiprelativehumidityandtemperaturemultisensormodulecomprisingacalibrateddigitaloutput.Itcantestthesoiltemperatureandhumidity.TheDS18B20isadigitaltemperaturesensor,whichhas3pinsanddatapincanlinkMSP430directly.Itcandetecttemperatureingreenhouse.TheTCS320isadigitallightsensor.SHT11,DS18B20andTCS320arebothdigitalsensorswithsmallsizeandlowpowerconsumption.Othersensornodescanbeobtainedbychangingthesensors.

Thesensornodesarepoweredfromonboardbatteriesandthecoordinatoralsoallowstobepoweredfromanexternalpowersupplydeterminedbyajumper.

C.NodeSoftwareDesign

Theapplicationsystemconsistsofacoordinatorandseveralenddevices.Thegeneralstructureofthecodeineachisthesame,withaninitializationfollowedbyamainloop.

Thesoftwareflowofcoordinator,uponthecoordinatorbeingstarted,thefirstactionoftheapplicationistheinitializationofthehardware,liquidcrystal,stackandapplicationvariablesandopeningtheinterrupt.Thenanetworkwillbeformatted.Ifthisnethasbeenformattedsuccessfully,somenetworkinformation,suchasphysicaladdress,netID,channelnumberwillbeshownontheLCD.Thenprogramwillstepintoapplicationlayerandmonitorsignal.Ifthereisenddeviceorrouterwanttojoininthisnet,LCDwillshownthisinformation,andshowthephysicaladdressofapplyingnode,andthecoordinatorwillallocateanetaddresstothisnode.Ifthenodehasbeenjoinedinthisnetwork,thedatatransmittedbythisnodewillbereceivedbycoordinatorandshownintheLCD.

Thesoftwareflowofasensornode,aseachsensornodeisswitchedon,itscansall

channelsand,afterseeinganybeacons,checksthatthecoordinatoristheonethatitislookingfor.Itthenperformsasynchronizationandassociation.Onceassociationiscomplete,thesensornodeentersaregularloopofreadingitssensorsandputtingoutaframecontainingthesensordata.Ifsendingsuccessfully,enddevicewillstepintoidlestate;bycontrast,itwillcollectdataonceagainandsendtocoordinatoruntilsendingsuccessfully.

D.GreenhouseMonitoringSoftwareDesign

WeuseVBIanguagetobuildaninterfaceforthetestandthisgreenhousesensornetworksoftwarecanbeinstalledandlaunchedonanyWindows-basedoperatingsystem.Ithas4dialogboxselections:

settingcontrollingconditions,settingTimer,settingrelevantparametersandshowingcurrentstatus.Bysettingsomeparameters,itcanperformthefunctionsofcommunicatingwithport,datacollectionanddataviewing.

Zigbee无线传感器网络在环境监测中的应用

I.Zigbee技术

Zigbee是一种基于IEEE802.15.4的无线标准上被开发用来满足大多数无线传感和控制应用的独特需求。

Zigbee技术是低成本，低功耗，低数据速率，高可靠性，高度安全的无线网络协议实现自动化和远程