《信息科學類專業(yè)英語》課件第13章

Lesson13About4G

(第十三課關于4G)

Vocabulary(詞匯)ImportantSentences(重點句)QuestionsandAnswers(問答)Problems(問題)

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即將到來。

2.

Markn.標志,分數(shù),痕跡,記號vt.做標記于,打分數(shù),標志vi.作記號。

3.

hardlyadv.剛剛,幾乎不,僅,嚴厲的,艱辛的。

4.

carriern.運送者,郵遞員,帶菌者,行李架,搬運器,航空母艦，[電]載波(信號)。

5.

analoguen.相似物,類似物，類似語;同源語，相似器官;相似體；類比,比擬；模擬(量,裝置,設備,系統(tǒng),計算機)。Vocabulary6.

heraldn.使者,傳令官,通報者,先驅,預兆vt.預報,宣布,傳達,歡呼。

7.

comeabout出現(xiàn)，發(fā)生。

8.

proliferationn.增殖,分芽繁殖。

9.

spann.跨度,跨距,范圍v.橫越。

10.

speculationn.思考，思索；構思；推測。

11.?unanimously

adv.無異議地;全體一致地。12.?onsetn.開始，開端，發(fā)生，肇始(尤指不快的事件);攻擊,襲擊;【醫(yī)】發(fā)病。

13.?overhaul

vt.徹底檢查,大修;趕上,追上;超越;徹底革新或改革。

14.?exorbitant

adj.過度的,極高的。

15.?catapult

n.(小孩玩的)彈弓;石弩，弩炮vt.用弩炮發(fā)射，猛力推出；猛力推動。[1]Eachgenerationspannedaconsiderablenumberofyears.Therewereanumberofimprovementsandinnovationsthatwereintroduced,howeveronlythereallymajoronesweremarkedwithachangeingeneration.Mostofthesmalleronesreceivedanacknowledgmentbychangingthedecimalvalueofthegeneration.

每一代都會跨越許多年。對于其間的一些改進和革新，僅把那些真正重要的進展用作換代的標志。多數(shù)受到承認的較小的進展則用小數(shù)表示。注意，最后的句子的謂語(weremarked)省略了。ImportantSentences

[2]However,boththetechnologieshaveonecommonfactorwhichseemstounanimouslyheraldtheonsetof4G:orthogonalfrequency-divisionmultiplexingorOFDM.

但是兩種技術有一個共同的要素，這個要素看來無異議地預示著4G的有力開端，這就是正交頻分復用，或者OFDM。(1)

Whichiswrongaboutmobilegenerations?()

A.

Eachmajorevolutioninmobilephonetechnologyhasbeenmarkedbyageneration.

B.

Thesecondgenerationofmobilephonetechnologyisstillvisibleinmobilesnow.

C.

GPRS(GeneralPacketRadioService)isonetechnologyof3G.

D.

Whatexactlywillconstitute4Gmobiletechnologyhasnotbeenofficiallydefined.QuestionsandAnswers(2)

Whichiswrongabout4G?()

A.

WiMAXandLTEarethecontendersfor4G.

B.

OFDMunani