英文原文 附录二Word文件下载.docx

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Review

Thispaperexploresthestate-of-the-artresearchanddevelopmentofUWBapplicationsinmanysectors,includingtheconstructionindustry.Thispaperwillprovideinsightsintothetechnologyfortheun-initiatedreaderwithoutinvolvingdetailedtechnologicalandarithmeticaspectsofUWB.Todoso,thispaperfirstintroducesthekeyconceptsbehindUWBandprovidesabriefhistoricalperspective.Itthensumma-sizestheUWB’stechnicalfeatureswhichenableitsopopularinindustry.Finally,anumberofUWBapplicationexamplesinmanysectors,includingconstruction,arepresentedtoanalyzeandhighlighttheimpactontheindustryperformance.UWBtechnologyisexpectedtobecomeaveryimportantcomponentandhaveprofoundimpactinubiquitouscomputinginthenearfuture.

INRTODUCTION

ThispaperprovidesanintroductiontoUWBtechnology.ItpresentsUWBsystem’sprincipleswhichcharacterizethefunctionandcompositionofUWBsystemandbriefhistoryofUWBtechnology.Moreover,theUWB’stechnicalfeaturesaresummarizedtofacilitateprofoundunderstandingUWB’spopularity.SpecificemphasisisgiventotheUWBtechnology’sapplicationsinvariousindustriesincludingtheconstructionindustry.

DefinitionofuseofUWBsystems

UWBwirelesscommunicationsoffersaradicallydistinctapproachtowirelesscommunicationcomparedtotraditionalnarrowbandsystems.AccordingtotheFCC,UWBisanysignalthathasafractionalbandwidthequaltoorgreaterthan0.20orhasabandwidthequaltoorgreaterthan500MHz（Breed2005）.

UWBtechnologiescantransmitextremelyshortandlowpowerelectro-magneticpulses.Theradiospectrumspreadsoveraverywidebandwidth（Shenetal.2008）.Duetoitsshortpulseradiofrequency（RF）waveformsandlargebandwidth,UWBprovidesfinetimeresolutionandprovidesgoodpotentialforapplicationinrangingandpositioningandwellimmunitytomultipatheffects.

ThetagsinUWBtrackingsystemdecidethelocalizationdimensionality,receptionbythreeormorereceiverspermitsaccurate2Dlocalization,whilereceptionbyfourormorereceiversallowsforpre-cise3Dlocalization.Ifonlyoneortworeceiverscanreceiveatagtransmission,proximitydetectioncanalsobereadilyaccomplished（Khouryetal.2009）.

Commerciallyexistingultrawidebandsystems（seeprinciplelayoutillustratedinFig.1）includethefollowing（Teizeretal.2008;

Girettietal.2009）:

▶Processingcomputerandhubincludingagraphicaluserinterface;

▶MinimumoffourUWBreceiversatdifferentheightlevelstorecordreal-timethree-dimensionalsignaldatainafieldofviewof90°

（mid-gain）,60°

（highgain）,andomni-directional;

▶CAT-5eshieldedwires（wirespotentiallytobereplacedwithawirelesssignaltransmission）;

▶Low-andhigh-poweredUWBtags（approvedforsafeusebyFCC:

5mW,1W）withdifferentemittingsignalrefreshratesof1,15,30,or60Hz,includingonereferencetag.

▶TheUWBsystemoperatesasfollows:

asetof3ormorereceiversarepositionedatknowncoordinatesabouttheperipheryoftheareatobemonitored.Short-pulseRFemissionsfromtagsaresubsequentlyreceivedbyeitherall,orasubset,ofthesesensorsandprocessedbythecentralhub’sCPU.Atypicaltagemissionconsistsofashortburst,includedasetofdataforIDpurposes,repeatedatgivenfrequency（limitedbetween1and60Hz）.Timedifferencesofarrival（TDOA）ofthetagburstatthevariousreceiversaremeasuredandsentbacktothecentralprocessinghub.Calibration（i.e.signalspeedmeasuring）isperformedatsystemstartupbymonitoringdatafromareferencetag,whichhasbeenplacedattheknownlocation.Every

receiverobtainsitspowerfromthecentralprocessinghubviastandardCAT-5cables,whicharealsousedtocarrydatabacktothehubforsubsequentprocessing（Girettietal.2009）

AbriefhistoryofUWB

Althoughrecentlyconcernedextensiveresearchinterest,UWBtechnology’sorigincandatebacktoworkintheearly1960sontime-domainelectromagneticwavepropagation.BennettandRoss

summarizedUWB’searlyapplicationinaseminalpaper（Bennettetal.1978）.RosswasthefirstresearchertodemonstrateanUWBcommunicationsystemin1986.Thefirst（1973）fundamentallandmarkpatentonUWBcommunicationssystemssimplyreferredtothetechno-logyas“base-bandpulse”（Ross1973;

Barrett2000）.Theterm“UWB”originatedwiththeDefenseAdvancedResearchProjectsAgency（DARPA）inaradarstudyundertakenin1990,servingasaconvenientmeansfordiscriminatingbetweenconventionalradarandthoseutilizingshort-pulsewaveformshavingalargefractionalbandwidth（Fontana2004）.

TheearlyUWBsystemsweredesignedformilitary,lowprobabilityofdetectionradar,andcommunicationsapplications（Fontana2004）.Until1994,themajorityoftheworkwasperformedunderUSgovernmentprograms.WiththerulingsoftheFEDERALCommunicationsCommission（FCC）undertheU.S.government,after1994,therehasbeenanincreaseinnongovernmentalrelatedresearchandanincreaseinthenumberofUWBgovernmentagenciesandcompaniesthataregreatlyacceleratingthedevelopmentofUWBtechnology（Breed2005）（Teizeretal.2007）.In2002,theFCCapprovedtheunrestricteduseoflow-poweredUWBsystemsandtags[5milliwatts（mW）].Byfar,asoneoftheearliestcivilianapplicationsofUWB,Fontanaetal.[（Fontanaetal.2003）]utilizedUWBforaccurateassetslocalization.Firsttimeofarrival（TOA）measurementwasadoptedtoachievethepositionaccuracyofbetterthanonefoot.OtherearlyresearchincludedFontana（Fontana2004）andParketal（Parketal.2004）.Fontanadiscussedrecenttechniquesforthegenerationandreceptionofshort-pulseelectromagneticwaveformsandexaminedanumberofrecentlydevelopedUWBsystemsinthecommunications,radar,andprecision-positioningfields.ParketaldevelopedaUWBGPRsystemfordetectingsmallobjectsburiedunderground.

Owingtotheconsiderationaboutpotentialinterferencetoexistingandfutureplannedservices,theprocessofestablishingrulesofUWBfrequencyrangeisusuallytime-consuming.Atpresentfewcountriesandareas,suchasUSA,Euro-pe,haveestablishedtherules,howeverinmanyothercountries,UWBdeviceshaveyettobeapproved（Allenetal.2005;

Teizeretal.2008）.

IntheU.S.A.,theFederalCommunicationsCommission（FCC）hasmandatedthatUWBradiotransmissioncanlegallyoperateintherangefrom3.1GHzto10.6GHz（Fontana2004）（FCCNEWS）（Ingrametal.2004）.

IntheU.S.A.,theFederalCommunicationsCommission（FCC）hasmandatedthatUWBradiotransmissioncanlegallyoperateintherangefrom3.1GHzto10.6GHz（Fontana2004）（FCCNEWS）（Ingrametal.2004）.

UWB’stechnicalfeatures

Therearesomedistinctiveadvantagesofshort-rangehigh-bandwidthUWBwhicharesummarizedbelow（Bensky2004）（Fontanaetal.2003;

Teizeretal.2008;

Girettietal.2009）（Khouryetal.2009）:

▶highimmunitytointerferencefromotherradiosystems;

▶highmultipathimmunity,duetotheuseofveryshortUWBpulses,capableofdiscriminatingbetweendirectandtime-orthogonalreflectedwaves;

▶highdatarate;

▶highlocalizationaccuracy（forboth2Dand3D）,duetothereliabilityoftheTDOA（timedifferenceofarrival）algorithmimplemented;

▶extremelylowdutycycles,whichtranslatesintolowaverageprimepowerrequirementsallowingtagstoworkautonomouslyforyear,idealforbattery-operatedequipmentandwithoutfrequentrechargingneeds;

▶cantrackmultipleresourceatthesametime,realtimeandthree-deimensionally;

▶canworkinindoorandoutdoorenvironmentsatthesametime,reducingtheinstallationcostofmultiplesen-singunitstoaminimum;

▶longerindoorrangethanotherhighratecommunicationssystems,duetothehighpeak-to-averagepowerratio;

▶lighterweight,theweightforeachtagislessthan12g;

▶updaterateofRFsignalofeachtagcanbeupto60Hz;

▶needn’tcalibration.

ApplicationsofUWBinindustry

SinceUWBtechnologyhasshowntopossessuniqueadvantagesforprecisionlocalizationapplications,anumberofscientificandtechnicaldomainshavebenefitedfromUWB’ssuccessfulapplication,suchasmilitaryaffairs,medicaltreatmentandengineering.

UWBtechnologyisveryusefulformilitaryapplication.Becauseaveryshortdurationpulseimpliesalargeband,thepowerisspreadovernumerousfrequenciesinsteadofbeingconcentrated.Theresultantpowerspectraldensityisverylowandtheprobabilityofdetectionandinterceptionisverylow.

InthefieldofhighpowerUWBtechnology（electromagneticdetection）formilitaryapplication,animpulseUWBradarhavethefollowingfeatures:

▶Abilitytodetectthroughobstaclesandindensemedia;

▶Improvementoftheradarrangersolution;

▶Improvedclutterrejection;

▶Improveddetectionoflowflyingtargets;

▶Improveddetectionof（stealthornot）target;

▶Improvedrecognition（orevenidentification）oftargets;

▶Targetimagerymadepossible,usingaSyntheticApertureRadarmode（SAR）,whichgivesahighcross-rangeresolutionaddedtothehighrangersolution;

▶Accesstolowpulserepetitionfrequencymodewithoutrange-velocityambiguity.

AnexperimentalUWBradarwasdeveloped,calledPULSAR,toassessthebenefitofUWBconcerningthedetectionoftargetsmaskedbyvegetation,oranti-tankmines.

InthefieldoflowpowerUWBtechnologyformilitaryapplication,wirelesscommunicationsandlocalization-identificationaretwomajorapplicationfields.Twotechnicalapproachescan

beinvestigatedinwirelesscommunications.ThefirstapproachisutilizingUWBasradiolinkbetweenbodyandweapon/headdevicestotransmitdataorvideobetweenthecameraonthe

weaponsystemand