Zigbee无线传感器网络英文文献与翻译Word文档格式.doc
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Zigbee无线传感器网络英文文献与翻译Word文档格式.doc
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ZigbeeisawirelessstandardbasedonIEEE802.15.4thatwasdevelopedtoaddresstheuniqueneedsofmostwirelesssensingandcontrolapplications.Technologyislowcost,lowpower,alowdatarate,highlyreliable,highlysecurewirelessnetworkingprotocoltargetedtowardsautomationandremotecontrolapplications.It’sdepictstwokeyperformancecharacteristics–wirelessradiorangeanddatatransmissionrateofthewirelessspectrum.ComparingtootherwirelessnetworkingprotocolssuchasBluetooth,Wi-Fi,UWBandsoon,showsexcellenttransmissionabilityinlowertransmissionrateandhighlycapacityofnetwork.
A.ZigbeeFramework
Frameworkismadeupofasetofblockscalledlayers.Eachlayerperformsaspecificsetofservicesforthelayerabove.AsshowninFig.1.TheIEEE802.15.4standarddefinesthetwolowerlayers:
thephysical(PHY)layerandthemediumaccesscontrol(MAC)layer.TheAlliancebuildsonthisfoundationbyprovidingthenetworkandsecuritylayerandtheframeworkfortheapplicationlayer.
Fig.1Framework
TheIEEE802.15.4hastwoPHYlayersthatoperateintwoseparatefrequencyranges:
868/915MHzand2.4GHz.Moreover,MACsub-layercontrolsaccesstotheradiochannelusingaCSMA-CAmechanism.Itsresponsibilitiesmayalsoincludetransmittingbeaconframes,synchronization,andprovidingareliabletransmissionmechanism.
B.Zigbee’sTopology
Thenetworklayersupportsstar,tree,andmeshtopologies,asshowninFig.2.Inastartopology,thenetworkiscontrolledbyonesingledevicecalledcoordinator.Thecoordinatorisresponsibleforinitiatingandmaintainingthedevicesonthenetwork.Allotherdevices,knownasenddevices,directlycommunicatewiththecoordinator.Inmeshandtreetopologies,thecoordinatorisresponsibleforstartingthenetworkandforchoosingcertainkeynetworkparameters,butthenetworkmaybeextendedthroughtheuseofrouters.Intreenetworks,routersmovedataandcontrolmessagesthroughthenetworkusingahierarchicalroutingstrategy.Meshnetworksallowfullpeer-to-peercommunication.
Fig.2Meshtopologies
Fig.3isanetworkmodel,itshowsthatsupportsbothsingle-hopstartopologyconstructedwithonecoordinatorinthecenterandtheenddevices,andmeshtopology.Inthenetwork,theintelligentnodesarecomposedbyFullFunctionDevice(FFD)andReducedFunctionDevice(RFD).OnlytheFFNdefinesthefullfunctionalityandcanbecomeanetworkcoordinator.Coordinatormanagesthenetwork,itistosaythatcoordinatorcanstartanetworkandallowotherdevicestojoinorleaveit.Moreover,itcanprovidebindingandaddress-tableservices,andsavemessagesuntiltheycanbedelivered.
Fig.3Zigbeenetworkmodel
II. THEGREENHOUSEENVIRONMENTALMONITORING
SYSTEMDESIGN
Traditionalagricultureonlyusemachineryandequipmentwhichisolatingandnocommunicatingability.Andfarmershavetomonitorcrops’growthbythemselves.Evenifsomepeopleuseelectricaldevices,butmostofthemwererestrictedtosimplecommunicationbetweencontrolcomputerandenddeviceslikesensorsinsteadofwireconnection,whichcouldn’tbestrictlydefinedaswirelesssensornetwork.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,sinknodei
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- Zigbee 无线 传感器 网络 英文 文献 翻译
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