物联网翻译.docx

物联网翻译.docx

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物联网翻译

第一题：

TheproposedIoTarchitecturefromatechnicalperspectiveisshowninFig.1.Itisdividedintothreelayers.Thebasiclayerandtheirfunctionalitiesaresummarizedasfollows:

Perceptionlayer:

itsmainfunctionistoidentifyobjectsandgatherinformation.Itisformedmainlybysensorsandactuators,monitoringstations（suchascellphone,tabletPC,smartphone,PDA,etc.）,nano-nodes,RFIDtagsandreaders/writers.Networklayer:

itconsistsofaconvergednetworkmadeupofwired/wirelessprivatelyownednetworks,Internet,networkadministrationsystems,etc.Itsmainfunctionistotransmitinformationobtainedfromtheperceptionlayer.

Applicationlayer:

itisasetofintelligentsolutionsthatapplytheIoTtechnologytosatisfytheneedsoftheusers.

2.1.Perceptionlayer

Thislayerprovidescontext-awareinformationconcerningtheenvironmentofdisabledpeople.Thecomponentsofthislayeraccordingtothedisabilityoftheperson（visuallyimpaired,hearingimpairedorphysicallyimpaired）aredescribednext.

2.1.1.Visuallyimpaired

Thecomponentsdesignedforthevisuallyimpairedare:

（1）bodymicro-andnano-sensorsand

（2）RFID-basedassistivedevices.Next,thosecomponentsareintroduced.

2.1.1.1.Bodymicro-andnano-sensors.InSchwiebertetal.（2001）,aretinalprosthesisisdevelopedtorestoresomevisiontopatientsaffectedbyretinitispigmentosaandage-relatedmaculardegeneration,twodiseasesthatcausedegenerativeblindness.Althoughthesedisordersarecharacterizedbytheprogressivelossofphotoreceptor（rodandcone）cellsoftheouterretina,theydonotaffecttheinnerretinalganglionnervecellswhichformtheopticnerve（Yeetal.,2010）.Consequently,acameramountedonapairofglassescanbeusedtotransmitimagedatatoanimplantattachedtotheretina,whichisformedbyanarrayofbodymicro-sensors.Thisartificialretina（Schwiebertetal.,2001）useselectricalimpulsestostimulatetheappropriateganglioncells,whichconverttheseelectricalimpulsesintoneurologicalsignals.Thegeneratedresponseiscarriedviatheopticalnervetothebrain.

Currently,researchersareworkingtodevelopanartificialretinaatthenanoscale.TheventureNanoRetinaisdevelopingBio-Retina,abionicretinathatincorporatesseveralnano-sizedcomponentsinatinyretinalimplant（seeFig.2）.Bio-Retinaisdesignedtoreplacethedamagedphotoreceptorintheeyewiththeequivalentofa5000pixel（secondgeneration）retinalimplant.Ittransformsnaturallyreceivedlightintoanelectricalsignalthatstimulatestheneurons,whichsendtheimagesreceivedbyBio-Retinatothebrain.Theimplant’snano-sizedcomponentsarepoweredbyaspecialpairofactivationeyeglasses.Inthenextyears,astechnologyevolves,itwillbepossibletosendinformationconcerningtheimagescapturedbytheartificialretinatowardsthemonitoringstation（smartphone）（seeFig.1）,sothatnewIoTapplicationstohelppeoplewithvisualimpairmentsintheirorientation,identificationoffaces,etc.willbedeveloped.

2.1.1.2.RFID-basedassistivedevices.AnessentialRFID-basedapplicationisthenavigationsystem.Ithelpsblindpeoplefindtheirwayinanunfamiliararea.RFIDtagsaredistributedthroughthearea.Theycanforexamplebeplacedinthecenterofthesidewalkstoorienttheblindpersonandpreventpossiblefallsneartheborderofthesidewalk（Saaidetal.,2009）.

TheRFIDcane（seeFig.1）hasatagreaderwithanantennathatemitsradiowaves;thetagsrespondbysendingbacktheirstoreddata,henceidentifyingthelocationoftheblindperson.Thetagreader（RFIDcane）transmitsviaBluetoothorZigBeethedatareadfromtheRFIDtag,whichincludesthetagIDstring（D’Atrietal.,2007）.ThisdataissentfromthemonitoringstationthroughthenetworklayertotheRFIDserveroftheapplicationlayer.Theblindpersoncanrecordthedestination’snameasavoicemessageusingthemonitoringstation.Directionsarereceivedbythemonitoringstationandplayedasvoicemessages（Shiizuetal.,2007）.

Anobstacledetectionsystembasedonanultrasonicsensorcanalsobeadded（Martinetal.,2009）.ThesensorismountedontheRFIDcanetoextenditseffectiverangeandperceiveobstaclesthecanealonewouldnotbeabletodetect（suchasagarbagecaninFig.1）.Avoicemessageplayedatthemonitoringstationalertsthevisuallyimpairedwhenanobstacleisdetected.Amultiplesensor-basedshoe-mountedsensorinterfaceisalsodevelopedinZhangetal.（2010）asasupplementarydevicetothecanetodetectobstacleswithin61cmaheadofthevisuallyimpaired.

AwidespreadapproachforoutdoornavigationreliesonGlobalPositioningSystem（GPS）.Itdoesnotrequiretagstowork.However,itsresolutionislimited（fewmeters）anditcannotworkproperlyindoors.Therefore,somenavigationsystemsforthevisuallyimpairedintegratebothtechnologies（RFIDandGPS）（Yelamarthietal.,2010）.

Thislayer（seeFig.1）enablestheaccessofthemonitoringstationstotheradiochanneltotransmittheinformationobtainedfromtheperceptionlayer.AlthoughtheInternetprotocolswereoriginallydesignedforfixednetworks,thereisagrowingneedfortheseprotocolstoaccommodatemobilenetworks,asdemonstratedbytheuseofmanydifferentwirelessaccesstechnologiesinIoT（EUFP7ProjectCASAGRAS,2009）.ThedifferenttransmissionmediaincludeWirelessLocalAreaNetworks（WLANs）（IEEE802.11variants）,WorldwideInteroperabilityforMicrowaveAccess（WiMAX）（IEEE802.16）,Bluetooth（IEEE802.15.1）,Ultra-wideband（UWB）（IEEE802.15.4aandECMA-368）,ZigBee（IEEE802.15.4）,GeneralPacketRadioService（GPRS）andWidebandCodeDivisionMultipleAccess（WCDMA）.WirelessadhocnetworksareagoodoptiontoestablishwirelessandmobilecommunicationswithintheIoT,sincetheydonotrelyonapreexistinginfrastructure,theyrequireminimalconfig-urationandaredeployedquicklywithlowcost.Networkscomposedofdifferentaccesstechnologiesareknownasheterogeneousnetworksandtheyshouldmaintainconnectivityandservicefordifferentapplicationsevenwithusermobility.

TheconvergenceofheterogeneousnetworksandapplicationsispossibleduetotheexistenceofasingleInternetProtocol（IP）-basednetwork.TheIPforSmartObject（IPSO）Allianceisanon-profitassociationofmorethan50membersfromleadingtechnology,communicationsandenergycompanies.TheyadvocatetheuseofIPnetworkeddevicestobuildtheIoT（DunkelsandVasseur,2010）.TheystressthatIPisalong-livedandstablecommunicationtechnologythatsupportsawiderangeofapplications,devicesandunderlyingcommunicationtechnologies.Inaddition,theend-to-endIParchitectureislightweight,highlyscalableandefficient.Furthermore,theauthorsofInternetØalsorecommendtheuseoftheIPprotocoltooffertheInternet’sinteroperabilityandscalabilitydirectlytoembeddeddevicesratherthanneedinggatewaysforprotocolconversion（GershenfeldandCohen,2006）.

Itisnecessarytoensuretheconnectivity,interoperabilityandcompatibilityofheterogeneousnetworks.Thelow-powernet-workingindustry,fromZigBeeadhoccontroltoindustrialautomationstandards（e.g.ISA100）,isquicklyconvergingtotheuseofIPtechnology（ShelbyandBormann,2009）.Inthissense,6LoWPANisthenameofaworkinggroupoftheInternetEngineeringTaskForce（IETF）thathasdevelopedasetofInternetstandards,whichenabletheefficientuseofIPv6overLow-powerWirelessPersonalAreaNetworks（6LoWPANs）.6LoWPANenablesresource-limitedembeddeddevices（oftenbattery-powered）inlow-powerwirelessnetworkstobeInternet-connectedbysimplifyingIPv6（headercompressionofIPv6headerfields）andtakingthenatureofwirelessnetworksintoaccount.

TheIPv6protocolstackwith6LoWPANisshowninFig.4.Asmalladaptationlayer（namedtheLoWPANadaptationlayer）hasbeendefinedinthe6LoWPANprotocolstack（seeFig.4）tooptimizethetransmissionofIPv6packetsoverIEEE802.15.4andsimilarlinklayers（ShelbyandBormann,2009）.IEEE802.15.4isastandardthatdefinesthephysicalandMAClayersforlow-power,low-ratewirelessembeddedradiocommunicationsat2.4GHz,915MHzand868MHz.

TheadoptionofInternetprotocolsbywirelessembeddeddevicesischallengingduetoseveralreasons（ShelbyandBormann,2009）:

Battery-poweredwirelessdevicesrequirelowdutycycles,whereasIPisbasedonalwaysconnecteddevices.

MulticastisnotsupportednativelyinIEEE802.15.4butitisessentialinmanyIPv6operations.

Sometimesitisdifficulttoroutetrafficinmulti-hopwirelessmeshnetworkstoachievetherequiredcoverageandcostefficiency.

Lowpowerwirelessnetworkshavelowbandwidth（20–250kbit/s）andframesize（IEEE802.15.4packetsarerathersmall,127bytesmaximumatthephysicallayer,minusMAC/securityandadaptationlayeroverhead）.Ontheotherhand,theminimumdatagramsizethatallhostsmustbepreparedtoaccept,forIPv6is1280bytes.IPv6requiresthateverylinkintheInternethasaMaximumTransmissionUnit（MTU）of1280bytesorgreater.Onanylinkthatcannotconveya1280-bytepacketinonepiece,link-specificfragmentationandreassemblymustbeprovidedatalayerbelowIPv6.

Standardprotocolsdonotperformwellinlow-powerwirelessnetworks.Forexample,TCPperformsverypoorlyinwirelessnetworksduetoitsinabilitytodistinguishbetweenpacketlossesduetocongestionandthoseduetochannelerror.

2.3.Applicationlayer

Thislayer（seeFig.1）providesanoperationsupportplatform,whichcanbeaccessedbymonitoringstationsandapplications.Itprovidesimportantfunctionalitiessuchasauthentication,billing,servicemanagement,serviceacceptanc