通信工程 毕业设计外文文献翻译：超宽带系统的数据通信文档格式.docx

通信工程 毕业设计外文文献翻译：超宽带系统的数据通信文档格式.docx

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10240FlandersCt.SanDiegoCA92121

E-mail:

{gopal.racherla,jason.ellis,susan.lin,david.furuno}@Website:

luwb

ABSTRACT

Ultra-Widebandt（UWB）isaradiotransmissionschemethatusesextremelylowpowerpulsesofradioenergyspreadacrossawidespectrumoffrequencies.UWBhasseveraladvantagesoverconventionalcontinuouswaveradiocommunicationsincludingpotentialsupportforhighdatarates,robustnesstomultipathinterferenceandfading.WepresentanoverviewofUWBtechnologyanditsuseindatacommunicationsandnetworking.WelookatdesignconsiderationsforUWBbasednetworksatvariouslayersoftheprotocolstack.

1.INTRODUCTION

Ultra-Wideband[1-6]一alsoknownasbasebandorimpulseradio一isacarrier-freeradiotransmissionthatusesnarrow,extremelylowpowerpulsesofradioenergyspreadacrossawidespectrumoffrequencies.UWBhasrecentlygainedagreatdealofinterestduetotherecentFederalCommunicationsCommission（FCC）ReportandOrderwhichallocatestheUWBband一7.5GHzofunlicensedspectrumforindoorandoutdoorcommunicationapplications.UWBcommunicationsarerequiredtohavea-10dBfractionalbandwidthofmorethan20%ora-10dBbandwidthofmorethan

500MHz[7].ItisimportanttonotethattheFCChasnotdefinedaspecificmodulationschemetobeused.UWBsystemsofferthepromiseofhighdatarate,lowsusceptibility

tomultipathfading,hightransmissionsecuritylowprimepowerrequirements,lowcost,andsimpledesign[1,2,5,6].UWBhasbeenusedinmilitaryapplicationsforthepastseveralyearsforground-penetratingprecisionradarapplicationsandsecurecommunications[3,8].Forthepastfewyears,UWBhasbeendevelopedforcommercialapplications[1,2,5,6].WiththerecentFCC[7]reportandorderforthe

useofUWBtechnology,therehasbeenanaddedimpetustothisendeavor.OthernotableUWBapplicationsincludecollisionavoidanceradar,tagging/identification;

geolocation[9]anddatacommunicationsinpersonalareanetworks（PAN）andlocalareanetwork（LAN）environments.

UWBpresentsagreatopportunityfordatacommunicationsfortoday'

smedia-richconsumerelectronicsandhomeentertainmentsystemsthatrunonbatterypoweredhandhelddevices.Itcanformthebasisofalowcost,lowpowerandveryhighdataratesolutionasawireless"

cablereplacement"

technologyforcomputer-to-peripherals,peripherals-to-peripheralsanddigitalhomenetworkingapplications.AveryusefulattributeofUWBtechnologyisitsabilitytoperformprecisiongeo-locationwhichcanaidinad-hocormeshnetworkingwheretheoperationsofthemobilehostsbenefitbyknowingthelocationoftheotherhosts.UWBtechnologypromisestofillthevoidleftbyestablishedstandardslikeBluetoothand802.11a/b/g.

ThereareseveralfuturechallengestothewideadoptionofUWBforwirelessdatacommunicationsincludingtheinfancyofthetechnologyinthecommercialarena,lackofreliable

channelmodels,theearlystagesofstandardizationeffortandlackoflow-costsystemonchip（SoC）implementations.Inthispaper,welookatUWBtechnologyfordatacommunicationsandinsideaUWBphysical（PHY）layercharacteristics.Wealsobrieflyintroduceotherrelatedwirelessstandardssuchas802.11[10],802.15.3[11-13]Bluetooth[14],HomeRF[15]andHIPERLAN[16]andpresentabriefsynopsisoftheregulatoryeffortworldwidewithspecialemphasisontheFCC.WealsopresentthedesignconsiderationsforUWBbaseddatanetworking.

2.ULTRA-WIDEBANDTECHNOLOGY

ThebasicwaveformthatemployedinaUWBsystemisanapproximationtoanimpulse,suchasthatshowninFig.1.Theshortdurationofthepulseisassociatedwithlargeinherentbandwidth;

hence,thenomenclature"

Ultra-Wideband"

.TypicalattributesofUWBwaveformsaresummarizedinTable1.

Fig.1.UWBwaveformexample.

ThehighspectralcontentoftheUWBwaveformgivesrisetooneoftheprimaryadvantagesUWBoperationforcommunicationswhereaUWBsystemisrobustagainstmultipathfading[17]andnarrowbandinterference[18].Inmultipathfading,wherethetransmittedradiofrequency（rt）signalcanreflectoffobjectsinitstransmissionpathandcancausedestructiveinterferencesatthereceiver,alossofreceptioncanoccur.This

Table1:

CharacteristicsofTypicalUWBSystemsFractionalBandwidth>

20%

PulseWidth0.1-2as

PulseRepetitionFrequency1kHz-2GHzAverageTransmittedPower<

1mW

effectisparticularlyproblematicindoorswheretherearemanyreflectingsurfaces.Inthefrequencydomain,multipathisshownasfrequencyselectivefading.BecauseUWBcommunicationssystemsspreadsthetransmitteddataoverabroadfrequencybandifd