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外文翻译--空白频段标志着无线界.doc

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外文翻译--空白频段标志着无线界.doc

http//www.eetasia.com/WhitespacesmarkedoffaswirelessarenaPosted16Oct2008WhenthelongawaitedDTVswitchoverintheUnitedStatesoccursnextFebruary,broadcasterswillrelinquishtheanalogchannelssomehaveheldformorethanhalfacentury.Consideringthepricesmobileoperatorspaidforbeachfrontspectrumabove700MHzearlierthisyear,theseunlicensedVHF/UHFchannelsknownaswhitespacesandscatteredthroughoutthe54MHzto698MHzregionoftheRFspectrumwouldeasilyhavepulledinbillionshadtheybeenauctioned.Buttheywerentandarangewarisragingoverhowtheyshouldbeused.Thefirstsquattersinthenewlyunlicensedchannelswilllikelybeahandfuloftechgiants,includingGoogle,HewlettPackard,MicrosoftandMotorola,whichhavejoinedwithpublicinterestgroupsandmediacompaniestocreatetheWirelessInnovationAllianceWIA.SeveralRFcompanieswithlinkstoWIAmembersaretestingprototypeproductsknownaswhitespacesdevicesWSDswiththeU.S.FederalCommunicationsCommissionFCC.SuperiorUHFpropagationTransmissionsfromtheseWSDswouldenjoyUHFpropagationcharacteristicsfarsuperiortothoseofthenowovercrowded2.4GHzband.ApplicationsrangefromadatanetworkthatGooglesLarryPagehasdescribedasWiFionsteroidstoallsortsofvideo,tonetworksofhumblehouseholdobjectslikewashingmachines,toastersandlightbulbs,allcommunicatingwithoneanother.ThebravenewwirelessworldenvisionedbytheWIAcouldpossiblydisrupttheairwaveswithinterferenceandundoubtedlywillupsetthebroadcastersVHF/UHFmonopoly.Thebroadcastersarelivid,describingtheplanasunworkable.Andalthoughneithersideissayingso,itisnotdifficulttotranslatebroadbandintovideoandunlicensedintodollars.TheFCChasjustconcludeditsfieldtestingofWSDsubmittedbyMotorola,Philips,Adaptrum,SharedSpectrum,andSingaporesInstituteforInfocommResearch.Thetestresultswillalmostcertainlystartanotherroundofvituperationbetweenthetechsandthebroadcasters.Thereisquiteabitofwhitespaceoutthere,particularlyinruralareasoftheU.S.,accordingtotheNewFrontiersFoundation,amemberofWIA.Butthecontestedturfisinlargemediamarketswherethebroadcastersrakeinmostoftheirprofits.NewFrontiers,whichbelievesthesociallyproactiveuseofwhitespacescanhelpclosethedigitaldivide,hasestimatedthepercentageofunusedspectrumvariesfrom18percentinNewYorktomorethan60percentinlessdenselypopulatedareas,suchasWichita,Kansas.Thesefiguresarecontestedbythebroadcastlobby,ledbyMaximumServiceTVMSTV,whichdescribesitselfastheengineeringarmoftheNationalAssociationofBroadcasters.DavidL.Donovan,presidentofMSTV,arguesthatyoucantjustadduptheDTVchannelsthatarenotlicensedinageographicarea,becausehighpowerTVsignalscantravelmanymilesbeyondtheirlicensedregion.Moreimportant,hesaid,isthepresenceoflowpowerdeviceslicensedtooperateintheVHF/UHFbands.WirelessmicrophonessuchasthoseusedbysportscasterswhointerviewcoachesandplayersonthesidelinesofsportingeventscanbelicensedtooperatelegallyintheVHF/UHFbandsalthoughmanymoreoperateunlicensed.BecausewirelessmicrophonesaremobileandtransmitatmuchlowerpowerthanDTVstations,theyrepresentatougherinterferenceproblemforWSDs.WIAisnottobedeterred.NotingthatmaximumWSDpowertransmissionhasbeenlimitedto100mW,WIAconsultantEdmundThomasisconfidenttheinterferenceproblemcanbesolvedbydeployingtherightsetoftechnologies.Atfirstglance,mostRFengineersmightthinkitundulycautioustofearthatlowpowerbelow100mWuseofpartofanunoccupied6MHzchannelcouldcauseproblemsforDTV,evenwiththelongerrangeofUHFsignals.RFengineershavebeensolvinginterferenceproblemsforyears,notablytheWiFi/Bluetoothcontentioninthe2.4GHzband.ButtheWIAhassetitscounterinterferencebarhigh.Twotechnologiesandpossiblyathirdwouldbeemployedglobalpositioningsystems,cognitiveradioandbeacons.Toguardagainstinterferencewithwirelessmikes,someWIAprototypesincludebeacontechnology.Whenabroadcastersetsupatasportingevent,forexample,itstechnicalteamwilldeployabeaconthatwillbroadcastatapowerthewhitespacesdevicescaneasilysense.IncumbentsintheVHF/UHFspace,whichincludebroadcastersandwirelessmicrophoneinterestsledbyU.S.manufacturerShureInc.,havelaunchedaspiritedverbalattackonWSDs.InfectionanalogyMSTVandagroupofstationsaskedtheFCCwhyitwouldconsiderallowingmillionsandmillionsoftheseinterferencecausingdevices,likegerms,tospreadthroughoutAmericawiththeabilitytoattacktheTVreceiversinpeopleshomes,apartments,hotelrooms,hospitalrooms,dormitories,etc.,withnowayfortheowneroftheTVsetthevictimtodeterminewhowascausingtheillnesstohisorherTVsetThatsortofrhetoricmightnotimpressengineers,butithasinducednofewerthan70membersofCongresstosignastatementexpressingdeepconcernabouttheuseofwhitespacesforpersonalwirelessdevices.Itsnotthatthereisntcauseforconcern.Themostoftennotedtechnologytrapisthesocalledhiddennodeproblem.Essentially,itisquitepossibleforaWSDtobeinapositionwhereitcannotsenseaDTVsignalwhileanearbyTVinanadjacentapartment,forexampleisreceivingthesignal.Thisismostlikelyinareasdensewithlargeconcreteandsteelstructures.AwirelesstechnologydeploymentwithaslargeamarketandpotentialpublicimpactasWSDswouldtypicallyattractalotofattentionfromtheIEEE.Inthepoliticalwrangleoverwhitespaces,however,itseemsasthoughnothingistypical.ExcludingmobileTheIEEEdoes,infact,haveaworkinggroupIEEEP802.22taskedwithdevelopingadetailedradiointerfacespecificationforacognitiveradiothatwouldshareairwaveswithTVtransmittersandwirelessmicrophonesintheUHFband.Thespecificationincludescognitiveradiotechniquestoavoidoratleastminimizeharmfulinterference.Atthegroupsverycreation,however,itsscopewaslimitedtofixedwirelessdevices,suchasthoseusedbywirelessInternetserviceproviders.MobiledeviceslikeWSDswerespecificallyexcluded.P802.22chairmanCarlR.StevensonhasnotroubledescribingWSDsandtheplanstodeploythemasillconceived.IbelievethatwhattheWIAisproposingtodoisarecipefordisaster,saidStevenson,aseasonedRFengineerwithalonganddistinguishedcareerinbothindustryandstandardsgroups.TheUHFspectrumactuallypropagatestoowellforshortrangedevices.Giventhisperspective,itshouldbenosurprisethatStevensonwasinstrumentalinlimiting802.22spurviewtofixeddevices.AsistypicalatIEEE,hisviewsarewellalignedwiththoseofthecompaniessponsoringhischairmanship.AlthoughmostIEEEchairsareemployeesofcompanieslargeenoughtohandletheexpensesequivalenttoasalaryIntelisagoodexample,someconsultantssupporttheirIEEEworkbyacquiringsponsors.Stevensontookthelatterroute.MSTV,ShureandQualcommallopponentsofWSDssponsorhisIEEEactivities.ThisiswithinIEEEguidelines,andsponsorshipdisclosuresaremadetotheIEEE.Stevensonsaysthereisnoconflictofinterestandthatnoneofhiscorporatesponsorshaveeverpressuredmeinanyway.Thebroadcasters,inparticular,broughtagreatdealofknowledgeandexpertiseinbroadcasttechnologytotheworkinggroup,hesaid.TheoutcomeofFCCtestingisstilluncertain,butifthecommissionallowsWSDs,thelackofastandardwillprobablylimittheirdeploymenttoahandfulofcompanies.Unlessextraordinarymeasuresaretakentoleveltheplayingfield,thecompaniestestingprototypeswillhaveaverybigjumpontherestoftheRFcommunity.Singlestream11nchipsattackWiFimainstreamAtherosCommunicationsInc.willtrytodrive802.11nintomainstreamWiFimarketswithanewlineofchipsusingastreamlinedversionofthespecification.TheAtherosAlignfamilyusesonlyasingleantennatotarget11gpricepoints.AnalystssaidtheyexpectotherWiFichipmakerstofollowsuitwiththeirownsinglestream11nproducts.However,theyalsocautionedthatthe11nmarketmayfaceconfusionfromtheemergingdiversityofconfigurations.Todaymost802.11nproductsuse2x2MIMOmultipleinput,multipleoutputantennastodeliverasmuchastentimesthethroughputofolder11gdevices.Howeveratnearlytwicethecost,the11ndevicescommandonlyaboutathirdthemarketshareof11g,despitethefacttheWiFiAlliancebegancertifyingdraft11nproductsinJune2007.Inthesecondquarterof2008,revenuefordraft11nproductsaccountedfor21percentofthemarketcomparedto64percentfor802.11gand15percentformultimodeb/g/a,accordingtoVictoriaFodale,asenioranalystwithmarketwatcherInStat.WehadOEMscomingtouswithplanstobuild200910deviceswithWiFi,buttheywantedtouse.11g,saidToddAntes,vicepresidentofmarketingatAtheros.Itwascleartousthenextlargeopportunityfor.11nwastomovelegacy.11gdesignsuptoamoreefficientstandard,headded.Bystrippingoutsupportformultipleradios,Atherosisbettingitcancreateanewclassofhighervolume11ndevicesthathittheestimated35pricingof11gpartsbutdeliverbetterperformance.Theprice/valuepropositionisclear,butthereisthepotentialforconsumerconfusionregardingproductcompatibilitysincethe11nspecificationallowsforone,two,three,orevenfourspatialstreams,saidFodaleofInStat.Indeed,Quantennarecentlybecamethelatestofseveralstartupstodebut11nchipswithaggressiveMIMOconfigurations,aimingatsupportforwholehomeWiFiandhighdefinitionvideo.AntessuggestedtheWiFiAllianceisworkingonasolutiontoletusersmixandmatchdifferentvariantsof11n.The11nstandardismuchricherthananythingwevehadtoworkwithbefore,coveringfromonetofourstreamproducts,Antessaid.Webelievethereisopportunityforfuturethreeandfourstreamproducts,butyouneedtohaveboththeclientandrouterproductstodelivertheperformanceandwethinkthatecosystemisprobablyayearormoreaway,headdedEndoftheroadfor11gInthemeantime,analystsexpectotherWiFiplayerssuchasBroadcomandMarvellmayrolltheirownsinglestreamproducts.Therewassomegoodlogicintheinitialleapoftheindustrytotwostreamproductsbecausetherewasasubstantialperformanceimprovement,butclearlyitleftopeningsatthelowerendforonestreamproducts,saidAntes.RedpineSignalsrecentlyreleasedan802.11nsinglestreammoduleforhandsetsandothersmallformfactordevices,saidFodale.Giventhecompetitivedynamicsofthismarket,Iwouldntbesurprisedtoseesimilarannouncementsfromotherchipsetvendorssoon,sheadded.AnteswouldnotdiscloseAtheroschippricing,buthesaidOEMscouldusetheAlignpartstobuildsystemsthathitthepricepointsofcurrent11groutersandgateways.

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