《信息科学类专业英语》课件第13章

Lesson13About4G

(第十三课关于4G)

Vocabulary(词汇)ImportantSentences(重点句)QuestionsandAnswers(问答)Problems(问题)

Eachmajorevolutioninmobilephonetechnologyhasbeenmarkedbyageneration.Currentlythethirdgeneration,betterknownas3G,istakingtheworldbystorm.However,manyindustryexpertshavepredictedthat4Gisjustaroundthecorner,sowhatis4G?1MobileGenerations

Thefirstwaveofmobilephonetechnologywashardlymobilebytoday’sstandards.Phonesweresolargethattheywerebuiltintobriefcase-likecarriersforeasyportability.Aroundthesametime,carphonesmadetheirdebut,sotelecommunicationnetworksweregearedtowardsservicingboththesedevices.Thenetworkswerepurelyanalogue,andwerenowhereclosetothekindoftechnologythatisnowvisible.However,althoughthedeviceswereextremelycumbersome,theyheraldedtheageofthenewertechnologythatissoprevalenttoday.Thesecondgenerationofmobilephonetechnologyisstillvisibleinmobilesnow,becausethesecondmajorinnovationwastheintroductionoftheGlobalSystemforMobileCommunications.PopularlyknownasGSM,thisstandardssystemalloweduserstocarrytheirmobilesacrosscountriesandstillhavenetworkaccess.Thesecondgenerationofmobileswasconsiderablysmaller,asmobilecircuitrybecamemoresophisticated.2The3GRevolution

Oncemobilesbecameapracticalnecessity,andalmosteveryonehadone,thenextgreatinnovationwasturningamobilephoneintoaminiaturepersonalcomputer.GPRS(GeneralPacketRadioService)cameaboutduringthesecondgeneration,butthetrueproliferationofmobileInternetwasbroughtonbyEDGE(EnhancedDataRatesforGSMEvolution).Thenewadvancessparkedbetterconnectivity,betterdownloadspeedsandtheoverallimprovedavailabilityofmobiledatanetworks.Eachgenerationspannedaconsiderablenumberofyears.Therewereanumberofimprovementsandinnovationsthatwereintroduced,howeveronlythereallymajoronesweremarkedwithachangeingeneration.Mostofthesmalleronesreceivedanacknowledgmentbychangingthedecimalvalueofthegeneration.[1]3Whatis4G?

MobileInternetstillfeaturesasamajorfactorforinnovation,asitstillcannothopetorivalthePC-boundInternetexperience.4Gisgoingtointroducewirelesstechnologiestomainstreammobilephones.Since4Ghasnotbeenofficiallydefinedbyanyone,thereisalotofspeculationastowhatexactlywillconstitute4Gmobiletechnology.Therearevariouscontendersfortherole;twoofthefrontrunnersbeingWiMAXandLTE.

However,boththetechnologieshaveonecommonfactorwhichseemstounanimouslyheraldtheonsetof4G:orthogonalfrequency-divisionmultiplexingorOFDM.[2]4OFDM

Currently,thereareanumberofwaysthatdataistransferredfromdevicetodevice.CDMA(codedivisionmultipleaccess)isonepopulartechnology,andTDMA(timedivisionmultipleaccess)isasecond.CDMAtransfersanumberofdifferentdatapacketsononechannel,usingcodestodistinguishbetweendifferentreceivers.TDMA,ontheotherhand,againusesonechannelbutallotseachdifferentdatapacketatimeslot.OFDMdiffersfromthesetechnologiessignificantly;thechannelitselfisdividedintonarrowbands,anddatapacketsaresentthrougheachbandindividually.Thismethodprovestobemuchmoreefficientthanthepreviouslyusedtechnologies,henceitisconsideredtobeanintegralpartofthe4Grevolution.Readmore:/mobile/emerging-platforms/

articles/69017.aspx#ixzz0s2PVb72m5WiMAX

WiMAX,simplyput,isbroadbandonawirelessconnection.TheexistenceofWiMAXwillensurethathigh-speedInternetaccessisavailableanywhereausergoes.Thehardwareisstillinthedesignstages,becausetheadoptionofthistechnologywillentailahugeoverhaulofexistingtelecommunicationnetworks.High-speedInternetaccesswilldrasticallychangeauser’smobileInternetexperience.Asitstands,theuserisrestrictedtocertainwebinteractionslikeuploadingphotosorvideos,andmaybeupdatingablogonceinawhile.Thedatatransferratesprevalentareexorbitantandthereforedatatransferisseverelylimited.Theimplementationofhigh-speeddataaccessonmobilephoneswillfinallycatapultthemobilephoneintoseriouscontentioninthepersonalcomputersegment.6LTE:Long-TermEvolution

Developedbythe3GPP(ThirdGenerationPartnershipProject)group,LTEisanewwirelessbroadbandtechnologythatdiffersfromWiMAX.LTEplacesgreatemphasisonIPaddresses,sinceitiscloselybasedupontheTCP/IPnetworkingskeleton.TheideaistocreateenoughIPaddressessothateachdevicehasauniqueone.HoweverthemainfocusofLTEisthatitisshapinguptobehighperformanceineveryway.Thetechnologyisn’tfullydevelopedasyet,butthecharacteristicsthatareemergingpromisegreatthings:highpeakratesfordatatransmission,reducedlatencyandscalablebandwidth.

AnimportantfeatureofLTEistheabilitytoco-existharmoniouslywithpreviousarchitectures.ThereforeaLTE-enablednetworkcanpassdatabackandforthfromaCDMAnetworkseamlessly.7iPhone4G

HotontheheelsoftheiPadrelease,iPhone4Ghandsetshavebeenrumouredforreleasethissummer.Everyyear,sincethefirstiPhonehandsetwaslaunched,therehasbeenanewversionofthephonereleasedregularly.Thisyearpromisestobenodifferent.Speculationisrifethatthe4GtackedontheendofthenewiPhonemeansthatthehandsetmayjustbe4Genabled.Theargumentposedhereisthatthe3Gmodelwasactuallythesecondphone,soitisprobablynotaversionnumberaspreviouslythought.

Applehasn’tconfirmedordeniedanythingasyet;thenewiPhonemaynotbe4Gatall,butanHD(highdefinition)model.ThisscenarioiscertainlymorecredibleastheimprovementsrequiredfortheiPhonetomeritthe4Gtagwillbequitesubstantial.84GisMAGIC

4Gnetworksarestillinthefluidstagesofdevelopment.Asofnow,itissometimesreferredtoasMAGIC(Mobilemultimedia,Anytime/any-where,Globalmobilitysupport,IntegratedwirelessandCustomizedpersonalservice)–whichbodeswellforamobilephoneuser.Itwillbeinterestingtowatchthetechnologiesunfoldoverthecourseofthenextfewmonths.1.

aroundthecorner即将到来。

2.

Markn.标志,分数,痕迹,记号vt.做标记于,打分数,标志vi.作记号。

3.

hardlyadv.刚刚,几乎不,仅,严厉的,艰辛的。

4.

carriern.运送者,邮递员,带菌者,行李架,搬运器,航空母舰，[电]载波(信号)。

5.

analoguen.相似物,类似物，类似语;同源语，相似器官;相似体；类比,比拟；模拟(量,装置,设备,系统,计算机)。Vocabulary6.

heraldn.使者,传令官,通报者,先驱,预兆vt.预报,宣布,传达,欢呼。

7.

comeabout出现，发生。

8.

proliferationn.增殖,分芽繁殖。

9.

spann.跨度,跨距,范围v.横越。

10.

speculationn.思考，思索；构思；推测。

11. unanimously

adv.无异议地;全体一致地。12. onsetn.开始，开端，发生，肇始(尤指不快的事件);攻击,袭击;【医】发病。

13. overhaul

vt.彻底检查,大修;赶上,追上;超越;彻底革新或改革。

14. exorbitant

adj.过度的,极高的。

15. catapult

n.(小孩玩的)弹弓;石弩，弩炮vt.用弩炮发射，猛力推出；猛力推动。[1]Eachgenerationspannedaconsiderablenumberofyears.Therewereanumberofimprovementsandinnovationsthatwereintroduced,howeveronlythereallymajoronesweremarkedwithachangeingeneration.Mostofthesmalleronesreceivedanacknowledgmentbychangingthedecimalvalueofthegeneration.

每一代都会跨越许多年。对于其间的一些改进和革新，仅把那些真正重要的进展用作换代的标志。多数受到承认的较小的进展则用小数表示。注意，最后的句子的谓语(weremarked)省略了。ImportantSentences

[2]However,boththetechnologieshaveonecommonfactorwhichseemstounanimouslyheraldtheonsetof4G:orthogonalfrequency-divisionmultiplexingorOFDM.

但是两种技术有一个共同的要素，这个要素看来无异议地预示着4G的有力开端，这就是正交频分复用，或者OFDM。(1)

Whichiswrongaboutmobilegenerations?()

A.

Eachmajorevolutioninmobilephonetechnologyhasbeenmarkedbyageneration.

B.

Thesecondgenerationofmobilephonetechnologyisstillvisibleinmobilesnow.

C.

GPRS(GeneralPacketRadioService)isonetechnologyof3G.

D.

Whatexactlywillconstitute4Gmobiletechnologyhasnotbeenofficiallydefined.QuestionsandAnswers(2)

Whichiswrongabout4G?()

A.

WiMAXandLTEarethecontendersfor4G.

B.

OFDMunani