专业英语课程报告-下载

6/6专业英语课程报告-下载Modernmobilecommunicationtechnology

Innowhighlytheinformationizationsociety,theinformationandthecorrespondencehavebecomethemodernsociety“thelife”.Theinformationexchangemainlyreliesonthecomputercorrespondence,butcorrespondstakesthetransmissionmethod,withthesensingtechnology,thecomputertechnologyfusesmutually,hasbecometheinternationalsocietyandtheworldeconomicdevelopmentpowerfulengineinthe21stcentury.Inordertoadaptthetimerequest,thenewgenerationofmobilecommunicationtechnologyseasonableandlives,thenewgenerationofmobilecommunicationtechnologyisthepeoplesaidthatthirdgeneration'scorecharacteristicisthewidebandaddressingturnsonnon-gaproamingbetweentherigidnetworkandnumerousdifferentcommunicationssystem'sgainsthemultimediacommunicationservices.

Alongwiththetimeprogress,thetechnicalinnovation,people'sliferequest'senhancement,themobilecommunicationtechnologyrenewalspeedisquiteastonishing,almosteveryothertenyearmobilecommunicationtechnologyhasatransformationupdate,fromthe1980s“themobilephone”topresent's3Ghandset,duringhashadtwomobilecommunicationtechnologytransformation,transitsfrom1GAMPSto2GGSM,fromGSMtoIMT-2000(i.e.3Gtechnology).Knowsmodernonmethemobilecommunicationtechnologytohavethefollowingseveralaspectimportanttechnology:

1.widebandmodulationandmultipleaccesstechnique

Thewirelesshighspeeddatatransmissioncannotonlydependonthefrequencyspectrumconstantlytheexpansion,shouldbehigherthanthepresentnumbermagnitudeatleastinthefrequencyspectrumefficiency,mayusethreetechnologiesinthephysicallevel,namelyOFDM,UWBandfreetimemodulationcode.OFDMwithotherencodingmethod'sunion,nimblyOFDMandTDMA,FDMA,CDMA,SDMAcombinesthemultipleaccesstechnique.Inthe1960stheOFDMmulti-channeldatatransmissionhassucceededusesinKineplexandtheKathrynhighfrequencymilitary

channels.OFDMhasusedin1.6Mbit/shighbitratedigitalsubscriberline(HDSL),6Mbit/sasymmetricaldigitalsubscriberline(ADSL),100Mbit/sreallyhighspeedfiguresubscriber'sline(VDSL),digitalaudiofrequencybroadcastanddigitalvideobroadcastandsoon.OFDMapplieson5GHzprovides54Mbit/swirelesslocalnetworkIEEE802.11aandIEEE802.11g,highperformancethisregionnetworkHiperLAN/2andETSI-BRAN,butalsotakesmetropolitanareanetworkIEEE802.16andtheintegratedservicedigitbroadcast(ISDB-T)thestandard.Compareswiththesingleloadfrequencymodulationsystemservicepattern,theOFDMmodulationservicepatternneedstosolvetherelativelybigpeakevenpowerratio(PAPR,PeaktoAveragePowerRatio)andtothefrequencyshiftingandthephasenoisesensitivequestion.Highspeedmobilecommunication'sanotherrequestisunderthewidenoisebandwidth,mustdemodulatethesignal-to-noiseratiotoreduceasfaraspossible,thusincreasesthecoverarea.Mayadopttheanti-fadingthefullstartpowercontrolandthepilotfrequencyauxiliaryfasttrackdemodulationtechnology,likethefrequencyrangeanti-fading'sRakereceiveandthetracktechnology,theOFDMAtechnologywhichdeclinesfromthetimedomainandthefrequencyrangeresistancetimeandthefrequencyselectivity,thelinkauto-adaptedtechnology,theunioncodingtechnique.

2.frequencyspectrumusefactorlifttechnique

Thefundamentalresearchpointedout:IntheindependentRayleighscatteringchannel,thedatarateandtheantennaseveraltenthlinearrelationships,thecapacitymayreachShannon90%.Islaunchingandthereceivingendmayobtainthecapacityandthefrequencyspectrumefficiencygainbythemulti-antennadevelopmentchannelspace.TheMIMOtechnologymainlyincludesthespatialmultiplyingandthespacediversitytechnology,concurrentorthesalvosameinformationenhancesthetransmissionreliabilityontheindependentchannel.Receivesanddispatchesthebilateralspacediversityisthehigh-capacitywirelesscommunicationsystemusesoneoftechnical.BellLabfreetime'soppositeangleBLAST(D-BLAST)capacityincreasetoreceiveanddispatchthebilateralsmallestantennanumberinadministrativelevelsthefunction.Thecrosstimedomainwhichandtheairzone

expansionsignalconstitutesusingMIMOmayalsoresistthemulti-diameterdisturbance.V-BLASTsystemwhenindoor24~34dB,thefrequencyspectrumusefactoris20~40bit/s/Hz.Butlaunchesandthereceivingenduses16antennas,when30dB,thefrequencyspectrumusefactorincreasesto60~70bit/s/Hz.Thesmartantennaautomatictrackingneedsthesignalandtheauto-adaptedfreetimeprocessingalgorithm,producesthedimensionalorientationwavebeamusingtheantennaarray,causesthemainwavebeamalignmentsubscribersignaldirectionofarrivalthroughthedigitalsignalprocessingtechnology,thesidelobeorzerofallsthealignmentunwantedsignaldirectionofarrival.Theauto-adaptedarrayantennas(AAA,AdaptiveArrayAntennas)disturbsthecounter-balancebalancer(ICE,InterferenceCancelingEqualizer)tobepossibletoreducedisturbsandcutstheemissivepower.

3.softwareradiotechnology

Thesoftwareradiotechnologyisinthehardwareplatformthroughthesoftwareeditionbyaterminalimplementationdifferentsysteminmanykindsofcommunicationservices.Itusesthedigitalsignalprocessinglanguagedescriptiontelecommunicationpart,downloadsthedigitalsignalprocessinghardwarebythesoftwareroutine(DSPH,DigitalSignalPocessingHardware).Byhasthegeneralopeningwirelessstructure(OWA,OpenWirelessArchitecture),compatiblemanykindsofpatternsbetweenmanykindsoftechnicalstandardsseamlesscut.UWBisalsocalledthepulsetoberadio,themodulationusesthepulsewidthinthenanosecondlevelfastriseandthedroppulse,thepulsecoverfrequencyspectrumfromthecocurrenttotheluckyhertz,doesnotneedintheradiofrequencywhichtheconventionnarrowbandfrequencymodulationneedstotransform,afterpulseformation,maydeliverdirectlytotheantennalaunch.

4.networksecurityandQoS

QoSdividesintowirelessandthewiredsidetwoparts,wirelessside'sQoSinvolvestheradioresourcemanagementandthedispatch,theadmissioncontrolandthemobilitymanagementandsoon,themobilitymanagementmainlyincludestheterminalmobility,individualmobilityandservicemobility.Wiredside'sQoSinvolvesbasedontheIPdiffSerdiscriminationserviceandtheRSVPend-to-end

resourcesreservationmechanism.MechanismmapsthewirelesssideIPdiffSerIPtheQoS.Networksecurityincludingnetworkturningonsecurity,corenetworksecurity,applicationsecurity,safetymechanismvisibilityandconfigurable.

Intheabovemodernmobilecommunicationkeytechnologies'sfoundation,hashadthelandhoneycombmobilecommunication,thesatellitecommunicationaswellasthewirelessInternetcommunication,thesemailingaddresscausedthecorrespondenceappearancetohavethehugechange,usedthedigitaltechniquethemodernwirelesscommunicationalreadytopermeatethenationaleconomyeachdomainandpeople'sdailylife,forthisreason,weneededtocarethatitstrendofdevelopment,hopeditdevelopedtowardmoreandmoreconvenientpeople'slife'sdirection,willletnowushavealookatthemodernmobilecommunicationthefuturetrendofdevelopment.Modernmobilecommunicationtechnologicaldevelopmentsevennewtendencies:First,mobilitymanagementalreadyfromterminalmanagementtoindividualmanagementandintelligentmanagementdevelopment;Second,networkalreadyfromsynchronizeddigitalcircuittoasynchronousdigitalgroupingandasynchronoustransfermode(ATM)development;Thethree,software'sdevelopmentsactuatedfromthealgorithmtotheprocedure-orientedandfacethegoaltendencydevelopment;Thefour,informationprocessinghavedevelopedfromthevoicetothedataandtheimage;Thefive,wirelessfrequencyspectrumprocessingalreadyfromnarrowbandsimulationtothenarrowbandCDMAdevelopment;Thesix,computershavedevelopedfromcentralprocessingtothedistributionalserverandintellectualizedprocessing;Theseven,semiconductordeviceshavedevelopedfromeachchip16,000,000,000,000/150MHzspeedVLSIto0.5/350MHzspeedVLSIand2,000,000,000,000,000/550MHzspeedVLSI.

Underthistendency'sguidance,themobileservicerapiddevelopment,itsatisfiedthepeopleinanytime,anyplacetocarryonthecorrespondencewithanyindividualthedesire.Themobilecommunicationrealizesinthefuturetheidealperson-to-personcommunicationservicewaythatmustbetaken.Intheinformationsupporttechnology,themarketcompetitionandunderthedemandcombinedaction,themobilecommunicationtechnology'sdevelopmentisprogressesbyleapsand

bounds,presentsthefollowingseveralgeneraltrends:1)networkservicedigitization,grouping;2)networkingwideband;3)networkingintellectualization;4)higherfrequencyband;5)moreeffectiveusefrequency;6)eachkindofnetworktendsthefusion.Theunderstanding,graspsthesetendencieshasthevitalpracticalsignificancetothemobilecommunicationoperatorandtheequipmentmanufacturer.

译文：

现代移动通信技术

在当今高度信息化的社会，信息和通信已成为现代社会的“命脉”。信息的交流主要依赖于计算机通信，而通信作为传输手段，与传感技术、计算机技术

相互融合，已成为21世纪国际社会和世界经济发展的强大动力。为了适应时代的要求，新的一代移动通信技术应时而生，新的一代移动通信技术即人们称之第三代的核心特征是宽带寻址接入到固定网和众多不同通信系统间的无隙缝漫游，获取多媒体通信业务。

随着时代的进步、科技的创新、人们的生活要求的提高，移动通信技术更

新换代速度相当惊人，差不多每隔十年移动通信技术就发生一次变革性换代，

从上个世纪80年代的“大哥大”到现在的3G手机，其间发生了两次移动通信技术的变革，从1G的AMPS过渡到2G的GSM，从GSM到IMT-2000（即3G技术）。就我所知现代的移动通信技术有以下几方面的重要技术：

1、宽带调制和多址技术

无线高速数据传输不能一味仅靠频谱的扩展，应在频谱效率上至少高于目

前一个数量级，可在物理层采用三项技术，即OFDM、UWB和空时调制编码。OFDM与其他编码方式的结合，灵活把OFDM与

TDMA、FDMA、CDMA、SDMA组合成多址技术。20世纪60年代OFDM的多路数据传输已成功用于Kineplex和Kathryn高频军事通信系统。OFDM已用于1.6Mbit/s高比特率数字用户线（HDSL），6Mbit/s不对称数字用户线（ADSL），100Mbit/s甚高速数字用户线（VDSL），数字音频广播和数字视频广播等。OFDM应用于5GHz上提供54Mbit/s无线本地网IEEE802.11a和

IEEE802.11g，高性能本地域网络HiperLAN/2和ETSI-BRAN，还作为城域网IEEE802.16和集成业务数字广播（ISDB-T）标准。与单载频调制制式相比，OFDM调制制式要解决相对大的峰均功率比（PAPR，PeaktoAveragePowerRatio）和对频率位移和相位噪声敏感的问题。高速移动通信的另一要求是在宽噪声带宽下，所需解调信噪比应尽可能降低，从而增加覆盖面积。可采取抗

衰落的快速发射功率控制和导频辅助快速跟踪相干解调技术，如频域抗衰落的Rake接收和跟踪技术，从时域和频域抵抗时间和频率选择性衰落的OFDMA技术，链路自适应技术，联合编码技术。

2、频谱利用率提升技术

理论研究指出：在独立Rayleigh散射信道中，数据速率与天线数成线性关系，容量可达Shannon的90%。在发射和接收端以多天线开发信道空间可取得容量和频谱效率的增益。MIMO技术主要包括空间复用和空间分集技术，在独立信道上并发或连发相同信息来提高传输可靠性。收发双方的空间分集是高

容量无线通信系统采用技术之一。贝尔实验室分层次空时的对角BLAST（D-BLAST）容量的增加为收发双方最小天线数的函数。利用MIMO所构成的跨时域和空域的扩展信号还可以抵抗多径干扰。V-BLAST系统在室内24～34dB时，频谱利用率为20～40bit/s/Hz。而发射和接收端均采用16天线，在30dB时，频谱利用率增至60～70bit/s/Hz。智能天线自动跟踪所需信号和自适应空时处理算法，利用天线阵产生空间定向波束，通过数字信号处理技术使主波束对准

用户信号到达方向，旁瓣或零陷对准干扰信号到达方向。自适应阵列天线（AAA，AdaptiveArrayAntennas）中干扰抵消均衡器（ICE，InterferenceCancelingEqualizer）可减少干扰和降低发射功率