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1、ZigbeeWirelessSensorAndIt’sApplicationsinEnvironmentalMonitoring1.1StandarsWirelesssensorstandardshavebeendevelopedwiththekeydesignrequirementforlowpowerconsumption.Thestandarddefinesthefunctionsandprotocolsnecessaryforsensornodestointerfacewithavarietyofnetworks.Someofth
2、esestandardincludeIEEE802.15.4,ZigBee,WirelessHART,ISA100.11,IETF6LoW-PAN,IEEE802.15.3,Wibree.Thefollow-ingparagraphsdescribesthesestandardsinmoredetail.IEEE802.15.4:IEEE802.15.4[37]istheproposedstan-dardforlowratewirelesspersonalareanetworks(LR-WPAN's).IEEE802.15.4focuse
3、sonlowcostofdeployment,lowcomplexity,andlowpowerconsumption.IEEE802.15.4isdesignedforwirelesssensorapplicationsthatrequireshortrangecommunicationtomaximizebatterylife.Thestandardallowstheformationofthestarandpeer-to-peertopologyforcommunicationbetweennet-workdevices.Devic
4、esinthestartopologycommunicatewithacentralcontrollerwhileinthepeer-to-peertopol-ogyadhocandself-configuringnetworkscanbeformed.IEEE802.15.4devicesaredesignedtosupportthephysicalanddata-linklayerprotocols.Thephysicallayersupports868/915MHzlowbandsand2.4GHzhighbands.TheMACl
5、ayercontrolsaccesstotheradiochannelusingtheCSMA-CAmechanism.TheMAClayerisalsoresponsibleforvalidatingframes,framedelivery,networkinterface,networksynchronization,deviceassociation,andsecureservices.WirelesssensorapplicationsusingIEEE802.15.4includeresidential,industrial,a
6、ndenvironmentmonitor-ing,controlandautomation.ZigBee[38,39]definesthehigherlayercommunicationprotocolsbuiltontheIEEE802.15.4standardsforLR-PANs.ZigBeeisasimple,lowcost,andlowpowerwirelesscom-municationtechnologyusedinembeddedapplications.ZigBeedevicescanformmeshnetworksco
7、nnectinghun-dredstothousandsofdevicestogether.ZigBeedevicesuseverylittlepowerandcanoperateonacellbatteryformanyyears.TherearethreetypesofZigBeedevices:Zig-Beecoordinator,ZigBeerouter,andZigBeeenddevice.Zig-Beecoordinatorinitiatesnetworkformation,storesinformation,andcanbr
8、idgenetworkstogether.ZigBeerouterslinkgroupsofdevicestogetherandprovidemul-ti-hopcommunicationac
