通信工程专业外文翻译--瑞利衰落环境下单蜂窝多载波DS-CDMA系统的频谱效率-豆柴文库

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外文原文

Spectralefficiencyofasingle-cellmulti-carrier
DS-CDMAsysteminRayleighfading
P.Varzakas,G.S.Tombras
LaboratoryofElectronics,DepartmentofPhysics,UniversityofAthens,GR-15784Athens,Greece
Received8June2005;receivedinrevisedform12September2005;accepted11March2006

Abstract:Thespectralefficiencyofamulti-carrierdirect-sequencecode-divisionmultiple-access(MC/DSCDMA)systemoperatinginaRayleighfadingenvironmentisinvestigatedandevaluatedintermsofthetheoreticallyachievablechannelcapacity(intheShannonsense)peruser,estimatedinanaveragesense.。Thisshortpapercoversoperationoftheconsideredsystemoverbroadcastcommunicationrandomlytime-varyingchannelsasapplicabletowirelessradionetworksandsingle-cellindoormobilesystemsandleadstothederivationofaclosed-formexpressionfortheachievedspectralefficiency.Furthermore,therelationbetweenthenumberoftheemployedsub-carriersandtheachievedspectralefficiencyisrevealed.

Keywords:Spectralefficiency;Channelcapacity;Multi-carriermodulation;Code-divisionmultipleaccess;Rayleighfading;

1.Introduction
Basedonorthogonalfrequency-divisionmultiplexing(OFDM),multi-carrierdirectsequencecode-divisionmultiple-access(MC/DS-CDMA)hasbeenproposedandinvestigatedinthecontextofhighdataratecommunicationovertime-variantchannels[1].InsuchaMC/DS-CDMAsystem,thedatasequence,multipliedbyaspreadingsequence,modulatesasetofNorthogonalfrequencycarriersratherthanasingleone,asitisthecaseinconventionalDS-CDMA.Inthispaper,weconsidertheoperationofasingle-cellMC/DS-CDMAsysteminaRayleighfadingenvironmentandevaluateitsspectralefficiencyintermsofthetheoreticallyachievablechannelcapacity(intheShannonsense)peruser,ontheconditionthatthisisestimatedinanaveragesense.Suchanapproachisjustifiedbythefactthatthespectralefficiencyachievedbyanymultipleaccesscommunicationsystemdependsonthephysicalmodelofthefadingradioenvironment,i.e.,onwhatisknownabouttheparticularfadingchannels.Forexample,ifnothingisknownforthefadingstatisticsofachannelthenitscountablecapacity(inbits/s)willbedictatedbytheminimumfades