文献翻译——蓝牙

外文文献资料BluetoothIntroductionBluetoothisaforever,limitedradioconnectthatresidesonamicrochip.ItwasoriginallyexpandedthroughSwedishmobilephonecreatorEricssonin1994asamethodtoletlaptopcomputersmakecallsaboveamobilephone.Asthen,numerousorganizationshavesignedontocreateBluetooththelow-powerthoughtlesswirelessaverageforabroadvarietyofdevices(LeVitus,216-220).IndustryspectatorsanticipateBluetoothtobefittedinbillionsofdevicesthrough2005.DiscussionDevelopedbyengineersatEricssoninthelate1990s,Bluetoothismoreandmorespecialtechnologythatfacilitatesthoughtlesswirelesscommunicationamongadiversityofelectronicdevices.Itsmainlyimportantaspectisthatitpermitsdevicesto“talk”(relocateandorchestratedata)wirelesslywitheachother,terminatingtherequirementfortheoutwardlycontinuoustangleofcables,cords,andadaptersimportantfornumeroustodaysexpertise.TheBluetoothSpecialInterestGroup(SIG)wasformedin1998tomanagetheexpansionandprologueofBluetoothknowledge(LeVitus,216-220).IBM,Intel,ToshibaandNokiaconnectedwithEricssonasthebeginningassociatesoftheSIG,andinexcessof8,000organizationshavecontractedsince.SoastotradeproductswiththeBluetoothrequirementandlogo,manufacturersshouldbeassociatesoftheSIGandthedevicesshouldmeetwell-outlinedcredentials.TheseproceduresmakesurethatBluetoothwirelessdevicesinternationalmayconversewitheachother,apartfromcompanyornationofderivation.SpeedandRangeRangeisapplicationspecificandalthoughaminimumrangeismandatedbytheCoreSpecification,thereisnotalimitandmanufacturerscantunetheirimplementationtosupporttheusecasetheyareenabling.Rangemayvarydependingonclassofradiousedinanimplementation:Class3radioshavearangeofupto1meteror3feetClass2radiosmostcommonlyfoundinmobiledevices,havearangeof10metersor33feetClass1radiosusedprimarilyinindustrialusecases,havearangeof100metersor300feetThatcreatesBluetoothtechnologyappropriatefortransportinglesserfilesforexamplecellphonecontractsandtextdocuments,alsoaslower-qualitypicturesandaudio(Kumkum,160-162).Attheserelocatespeeds;Bluetoothmaynotactuallydealstreamingvideoorhigh-qualitypicturesandaudioatthisend,exceptthispossiblywillalterinthefuturewhenfreshBluetoothstandardsareinitiated.SimpleandCompetenttoUtilizeCreatingandconfiguringBluetoothalloweddevicesismoderatelyuncomplicated,withlittleextracommotionthanacquirethetwodevicesclosetooneanotherandtwistthemon.Thereisnorequirementtomountdriversorfurthersoftwaretocomplexanad-hoc,personalwirelessnetwork(Kumkum,160-162).Ithasauniformorganization,meaningthatsometwowirelessproductsattributingBluetoothtechnology,despiteofproductornationoforigin,havetheabilitytoconversefaultlesslywitheachother.CommonApplicationsOneofthemainlyordinaryapplicationsofBluetoothishands-freecellphoneprocedure.AbouteachcellphonefashionedinourdayhasconstructedBluetooth(Meier,15-20).OnlypairphonewithaBluetoothheadset,andhemaytalkwhereashisphoneisinhispurseorpocket.SeveraloftodayscarstereosaswellhavefittedBluetoothforhands-freecallinginhisvehicle.Andifhisvehiclehasaplantstereoorgrown-upaftermarketonethathemerelydoesntwishtorestore,hemayyetlikehands-freeidentifyingwithaBluetoothcarkit.Bluetooth3.0Bluetooth3.0isthefreshBluetoothwirelesstypicaladoptedthroughtheBluetoothSIGonApril21,2009.Thefreshstandardsupportselevateddataremovespeedsandconstructsaheadtheprecedingstandards(Meier,15-20).Withitssuperiorspeed,thetechnologyhastheprobabletotransfiguretheconsumerelectronicsindustry.TechnologyPROTOCOLTheBluetoothtechnologystandardissettomakedifferentapplicationscan“communicate”witheachother.Remotedevicesincommunicationusethesameprotocolstacks,whiledifferentapplicationsneeddifferentprotocolstacks.But,everyapplicationneedsthedatalinklayerandphysicallayeroftheBluetoothtechnology.ThewholeBluetoothprotocolstacksisshownasblow.Notanyapplicationshouldusealloftheprotocols,butoneorsomelistsofthese.Thechartbelowshowstherelationshipbetweenprotocols,buttherelationshipmaychangeinsomeapplications.ThecompletelyprotocolstacksincludeBluetoothspecialprotocols(likeLMPandL2CAP)andnotspecialones(suchasOBEXandUDP).Thebasicprinciplefordesigningprotocolandprotocolstacksisthatuseexistinghighlevelprotocolaspossible,ensurethecombinationofprotocolsandBluetoothtechnology,andtakethebestadvantageofthesoftwareandhardwarewhichadapttotheBluetoothtechnologystandards.TheopenBluetoothtechnologymakesdevicemanufacturerscanchooseprotocolsfreelyastheylikeorusedto.TheprotocolsinBluetoothprotocolsystemTherearefourlayersinBluetoothprotocolsystemaccordingtotheSIGCoreprotocolsCablereplacementprotocolsTelephonycontrolprotocolsAdoptedprotocolsExcepttheprotocollayersabove,thestandardalsodefinesHost/ControllerInterface(HCI),whichprovidescommandinterfaceforbasebandcontroller,connectionmanager,hardwarestateandcontrolregister.BluetoothcoreprotocolsconsistofthespecialprotocolsmadebySIG.MostBluetoothdevicesneedcoreprotocols,whileotherprotocolsareuseddependonneedsoftheapplication.Afterall,cablereplacementprotocols,technologycontrolprotocolsandadoptedprotocolsbasedonthecoreprotocolsconstitutetheobject-orientedprotocols.CoreprotocolsLMP(LinkManagementProtocol)Usedforcontroloftheradiolinkbetweentwodevices.Implementedonthecontrollers.Itidentifiesandencryptsthroughlaunching,exchangingandcheckingtheconnection,anddecidesthesizeofbasebanddatapacketsthroughconference.Italsocontrolsthepowermodeandworkcycleofwirelessequipment,andconnectionstatusofunitequipmentinpiconet.L2CAP(LogicalLinkControl&AdaptationProtocol)Thisprotocolisusedtomultiplexmultiplelogicalconnectionsbetweentwodevicesusingdifferenthigherlevelprotocols,andprovidessegmentationandreassemblyofon-airpackets.InBasicmode,L2CAPprovidespacketswithapayloadconfigurableupto64kB,with672bytesasthedefaultMTU,and48bytesastheminimummandatorysupportedMTU.InRetransmission&FlowControlmodes,L2CAPcanbeconfiguredforreliableorisochronousdataperchannelbyperformingretransmissionsandCRCchecks.BluetoothCoreSpecificationAddendum1addstwoadditionalL2CAPmodestothecorespecification.ThesemodeseffectivelydeprecateoriginalRetransmissionandFlowControlmodes:EnhancedRetransmissionMode(ERTM):Thismodeisanimprovedversionoftheoriginalretransmissionmode.ThismodeprovidesareliableL2CAPchannel.StreamingMode(SM):Thisisaverysimplemode,withnoretransmissionorflowcontrol.ThismodeprovidesanunreliableL2CAPchannel.Reliabilityinanyofthesemodesisoptionallyand/oradditionallyguaranteedbythelowerlayerBluetoothBDR/EDRairinterfacebyconfiguringthenumberofretransmissionsandflushtimeout(timeafterwhichtheradiowillflushpackets).In-ordersequencingisguaranteedbythelowerlayer.OnlyL2CAPchannelsconfiguredinERTMorSMmaybeoperatedoverAMPlogicallinks.SDP(ServiceDiscoveryProtocol)ServiceDiscoveryProtocol(SDP)allowsadevicetodiscoverservicessupportedbyotherdevices,andtheirassociatedparameters.Forexample,whenconnectingamobilephonetoaBluetoothheadset,SDPwillbeusedfordeterminingwhichBluetoothprofilesaresupportedbytheheadset(HeadsetProfile,HandsFreeProfile,AdvancedAudioDistributionProfile(A2DP)etc.)andtheprotocolmultiplexersettingsneededtoconnecttoeachofthem.EachserviceisidentifiedbyaUniversallyUniqueIdentifier(UUID),withofficialservices(Bluetoothprofiles)assignedashortformUUID(16bitsratherthanthefull128)/vichitraCablereplacementprotocols(RFCOMM)Radiofrequencycommunications(RFCOMM)isacablereplacementprotocolusedtocreateavirtualserialdatastream.RFCOMMprovidesforbinarydatatransportandemulatesEIA-232(formerlyRS-232)controlsignalsovertheBluetoothbasebandlayer.RFCOMMprovidesasimplereliabledatastreamtotheuser,similartoTCP.ItisuseddirectlybymanytelephonyrelatedprofilesasacarrierforATcommands,aswellasbeingatransportlayerforOBEXoverBluetooth.Telephonycontrolprotocols(TCP).Telephonycontrolprotocol-binary(TCSBIN)isthebit-orientedprotocolthatdefinesthecallcontrolsignalingfortheestablishmentofvoiceanddatacallsbetweenBluetoothdevices.Additionally,TCSBINdefinesmobilitymanagementproceduresforhandlinggroupsofBluetoothTCSdevices.TCS-BINisonlyusedbythecordlesstelephonyprofile,whichfailedtoattractimplementers.Assuchitisonlyofhistoricalinterest.AdoptedprotocolsAdoptedprotocolsaredefinedbyotherstandards-makingorganizationsandincorporatedintoBluetoothsprotocolstack,allowingBluetoothtocreateprotocolsonlywhennecessary.Theadoptedprotocolsinclude:Point-to-PointProtocol(PPP):InternetstandardprotocolfortransportingIPdatagramsoverapoint-to-pointlink.TCP/IP/UDP:ForcommunicatingwiththedeviceconnectedtoInternet.ObjectExchangeProtocol(OBEX):Session-layerprotocolfortheexchangeofobjects,providingamodelforobjectandoperationrepresentation.Itusestheclient-servermode.WirelessApplicationEnvironment/WirelessApplicationProtocol(WAE/WAP):WAEspecifiesanapplicationframeworkforwirelessdevicesandWAPisanopenstandardtoprovidemobileusersaccesstotelephonyandinformationservices.TechnologySPECTRUMANDINTERFERENCEBluetoothtechnologyoperatesintheunlicensedindustrial,scientificandmedical(ISM)bandat2.4to2.485GHz,usingaspreadspectrum,frequencyhopping,full-duplexsignalatanominalrateof1600hops/sec.The2.4GHzISMbandisavailableandunlicensedinmostcountries.SIMfrequencybandisopentoallradiosystem,Sotheuseofacertainfrequencybandwillmeetunpredictableinterferencesources.Therefore,Bluetoothdesignsspecialfastacknowledgeandfrequencyhoppingtechniquetoensurethestabilityoflink.Frequencyhoppingtechniquetodividethebandintomanyfrequencyhoppingchannels,inaconnection,radiotransceiver“jump”fromachanneltoanotherconstantlyaccordingtocertaincodesequence.Onlysenderandreceivercommunicateaccordingtothislaw,andtherestofinterferencemaynotpressthesamerule.TheinstantaneousbandwidthofFrequencyhoppingisverynarrow,butthroughthespreadspectrumtechnologyitcanmakethenarrowbandwidthonehundredtimesexpandedintowideband,makingtheinfluenceofinterferencemaybecomeverysmall.Comparingtoothersystemsthatworkinthesamefrequencyband,frequencyhoppingofBluetoothworksfaster,datapacketofBluetoothisshorter,whichmakeitmorestablethantheotherERRORCORRECTIONBluetoothsupportscircuitswitchingandpacketswitchingtwotechniques,anddefinestwotypesoflinkconnection,namelyconnection-orientedsynchronouslink(SCO)andconnectionless-orientedasynchronouslink(ACL)Bluetoothusethreeerrorcorrectionmodels:1/3ForwardErrorCorrection(FEC),2/3forwardForwardErrorCorrectionandAutomaticRepeatRequest(ARQ).Purposetotheerrorcorrectionistoreducethepossibilityofretransmission,whileatthesametimeincreasetheextraexpenses,butinareasonableerrorlessenvironment,redundantbidswillreduceoutput.Sothepacketdefinitionitselfalsokeepsflexibleways.HencethesoftwarecanbedefinedwhethertoadoptFEC.Ingeneral,whenthechannelnoiseislarge,BluetoothsystemwillusesFEC,inordertoensurethequalityofcommunication:astoSCOlink,1/3FECisused;2/3FECisusedinACLlink.InunnumberedARQ,thedatasendinatimeslotmustreceiveaconfirmationofreceiptinthenexttimeslot.OnlywhenthedataischeckedtobewithoutmistakeafterheadererrordetectionandCRCatreceiverwilltheconfirmationsenttosender,oranerrormessagewillbesentback.RANGERangeisapplicationspecificandalthoughaminimumrangeismandatedbytheCoreSpecification,thereisnotalimitandmanufacturerscantunetheirimplementationtosupporttheusecasetheyareenabling.Rangemayvarydependingonclassofradiousedinanimplementation:Class3radioshavearangeofupto1meteror3feetClass2radiosmostcommonlyfoundinmobiledevices,havearangeof10metersor33feetClass1radiosusedprimarilyinindustrialusecases,havearangeof100metersor300feetPOWERInordertomakeaBluetoothequipmentcanalsobeinconnectioneveninaverylowpowerstate,Bluetoothstipulatesthreeenergysavingstate:Parkstate,HoldstateandSniffstate.Theenergysavingefficiencyofthesestatesdeclinesonebyone.ThemostcommonlyusedradioisClass2andusers2.5mWofpower.Bluetoothtechnologyisdesignedtohaveverylowpowerconsumption.Thisisreinforcedinthespecificationbyallowingradiostobepowereddownwheninactive.TheGenericAlternateMAC/PHYinVersion3.0HSenablesthediscoveryofremoteAMPsforhighspeeddevicesandtumsontheradioonlywhenneededfordatatransfergivingapoweroptimizationbenefitaswellasaidinginthesecurityoftheradios.Bluetoothlowenergytechnology,optimizedfordevicesrequiringmaximumbatterylifeinsteadofahighdatatransferrate,consumersbetween1/2and1/100thepowerofclassicBluetoothtechnology.SECURITYMobilityandopenofBluetoothsystemmakessafetyproblemsextremelyimportant.AlthoughthefrequencymodulationtechniqueusedbyBluetoothsystemhasalreadyprovidedacertainsecurity,butBluetoothsystemstillneedsafetymanagementtolinklayerandapplicationlayer.Inlinklayer,Bluetoothsystemprovidesauthentication,encryptionandkeymanagement,andotherfunctions.EachuserhasaPersonalIdentificationNumber(PIN),whichwillbetranslatedinto128bitlinkkeyforone-wayorboth-waycertification.Oncetheauthenticationfinished,linkwilluseencryphonkeytoencrypt.Thelinklayersecuritymechanismprovidesagreatdealofcertificationschemesandaflexibleencryptionscheme(meansallowtheconsultationofthelengthofpassword).Thismechanismisveryimportantwhentheequipmentsincommunicationarefromdifferentcountries,becausesomecountrieswillspecifymaximumpasswordlength.Bluetoothsystemwillselectthesmallestmaximumallowablepasswordlengthofallequipmentsinthepiconet.Bluetoothsystemalsosupportsthehighlevelofprotocolstackindifferentapplicationsofspecialsecuritymechanisms.Bluetoothsecuritymechanismbuildstrustrelationshipbetweendevicesrelyingonpins.Oncethisrelationshipestablished,thesepinscanbestoredintheequipment,inordertoconnectionmorequicklythenexttime.ApplicationTheBluetoothapplicationcanbedividedinto4mainaspects:Home,Work,EnrouteandEntertainment.HomeModernfamilyhomeissodifferentwithpervious.Withtheseamlessimprovementofmoderntechnology,moreandmorepeoplestarthomeoffice,livingmorefreelyandefficiently.Moreover,theyalsoextendthetechnologytootheraspectsmorethanfamilyoffice,suchasfamilylife.ByusingtheproductsofBluetoothtechnology,peopleareabletogetridofthecablesaroundthehomeoffice.Mouse,keyboard,printer,laptop,computer,earphoneandspeakerscanbeusedinaPCenvironmentwireless,whichnotonlyincreasetheofficeareaofbeauty,butalsoforinteriordecorationandtoprovidemorecreativefreedom.Inaddition,withmobiledevicesandhomePCtobesynchronousandsharecalendarinformation,usescanaccessthelatestinformationeverywhere,atalltimes.Bluetoothdevicescannotonlymakethehomeofficeeasier,butalsomakehomeentertainmentmoreconvenient:Youdonthavetoputasidetheguests,leftalonetochoosethemusic.Userscanstore30feetwirelesscontrolonaPCorAppleiPodaudiofiles.Bluetoothtechnologycanalsobeusedintheadapter,allowingpeoplesharewithfriendsbysendingphotostotheTVBluetoothHeadsetfromcameras,mobilephoneandlaptop.BTGOofASUSisanperfectexampleoftheBluetoothtechnologywhichhasthefunctionoffilesharingbackup,computerperformancereal-timeadjustmentBluetooth(BTTurboRemote),BluetoothmobilecomputerstoshareInternetaccess(BTtoNet),listeningtomusic,remotecontrol,synchronizationschedulingpersonalmanagement.Workpreviously,theofficeisusuallyinchaosforvariouswirestangled.Powercableforthedevice,connectionbetweenthecomputerandthekeyboard,printer,mouse,andcablesofPDA,allofthemmakeadisorderworkenvironment.Insomecases,thiswillincreasetheriskoftheoffice,suchastheemployeemaybetrippingoverwiresorcablesaround.However,withBluetoothwirelesstechnology,theofficenolongerexistmessywires,thewholeofficeislikeamachine,likeanorderlyandefficientoperation.PDAcanbesynchronizedwiththecomputersharingcalendarsandcontactlists,computerperipheraldevicescandirectlycommunicatewithemployeesthroughaBluetoothheadsetwhenwalkingintheofficeanswerthephone,allwithoutwires.NotlimitedtotheuseofBluetoothtechnologytosolvetheclutterofanofficeenvironment.Bluetoothenableddevicescanalsocreateinstantnetwork,allowinguserstosharepresentationsorotherfileswithoutcompatibilityore-mailaccessrestrictions.Bluetoothdevicescaneasilysetgroupmeetings,throughthewirelessnetworktoengageindialoguewithotheroffices,anddelivertheideastothecomputer.Whetherinanon-networked,ortryingtoholdaheateddiscussion,Bluetoothwirelesstechnologycanhelpuserseasilyconvenemeetings,improvingefficiencyandenhancingcreativecollaboration.Currently,therearemanyproductsonthemarketaresupportedbyBluetoothconnectionfromawirelessdevicetoanotherdevicetotransferfiles.ProductssimilaraseBeamProjectionenablekeeptherecordofthemeetingwireless,andotherdevicesaresupportedmulti-stakeholdersuggestions.Inordertoeliminatedesktopclutterconnection,wirelesshighoffice,Bluetoothwirelesskeyboard,mouse,andpresentationequipmentcanstreamlinetheworkspace.SimultaneouslyconnectingPDAorcellphonetocomputerwirelesslycanupdateandmanageuserscontactlistandcalendartimelyandeffective.Bluetoothalsohelpsuserscreateafast,effectiveandsecurewayofselling.ThereareagrowingnumberofBluetoothenabledmobiledevicesupportsales.SalesmencanusemobilephonestoconnectthroughGPRS,EDGEorUMTSmobilenetworktotransmitinformation.TheycanuseBluetoothtechnologytoconnectalaptopcomputerandmobileprintersothattheyprintareceiptforthecustomersite.Whetherintheoffice,atthedinnertable,orontheway,workerscanreducethewordprocessing,reducewaitingtimeforcustomerstoachieveseamlesstransaction.Improvelogisticsefficiency.ByusingBluetoothtechnologytoconnect,shippinggiantUPSandFedExhavebeensuccessfulinreducingtheneedforreplacementofcabletouse,andsignificantlyimproveworkerefficiency.EnroutePeoplefrequentlytraveltotheworkplace,homeandotherdestinations,whileBluetoothtechnologyprovidesexactlythewayforpeopletoaccessimportantpersonalinformationorcommunicationsconnectivity.Nomatterwhatrolepeopleare-parents,studentsormobileprofessionals-inthisfast-pacedworld,everyoneneedstocontinuetoaccessthenetworkortocommunicate.Avarietyofnewequipmentandnewtechnologiesareconstantlyenteringthemarket,toensurebettermobileconnectivity,andBluetoothwirelesstechnologyisusuallyachievedbypersonalwirelessconnectivity.Bluetooth-enabledmobilephone,PDA,laptopcomputer,headphonesandcarscanbeontheroadforhands-freecommunication,sothattheuserislocatedorcablebroadbandconnectionhotspotsremainoutsidethescopeoftheInternetnetworkconnection,aswellasPCandmobiledevicestosynchronizecontactsandcalendarentriesaccesstoimportantinformation.Bluetooth-enabledlaptopcomputersandotherportablecomputingdevicescanuseGRPS,EDGEorUMTStolinkthePCandwirelessPDAtotheInternethroughBluetooth-enabledmobilephoneseverywhereatalltimescreatingunlimitedhotpot,