Communication Technology 通信技术.docx

Communication Technology 通信技术.docx

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CommunicationTechnology通信技术

1Introduction

1.1Introductionoftheproject

Withthedevelopmentsofmodernsociety,communicationtechnologiesarebecomingmoreandmoreessentialtohumanbeings.Duringtheperiodfrom1920to2013,researchersmadeacomprehensiveimprovementinthefieldsofvoicequality,connectingspeed,communicatingsecurityandsoon.Inthisessay,themainbodyissubdividedintothreeaspects.Firstly,somecommunicationtechnologiesappliedinhistoryareshowninthefirstsessionfollowedbyanoverviewofthetechnologiesinmoderntimeswhichcoulddescribetheshiftfrom1Gto3G.Thenthesecondsectionismainlyfocusingonanalyzingtheadvantagesanddisadvantagesofeachcommunicationtechnology.Afterthat,aconclusionandapredictionispresentedtosumupthewholeinformationandtelltheimprovementsinthenearestfuturebriefly.

IntheprocessofworkingonthisprojectIcouldlearnagreatdealofknowledgevaluableforthefuturestudylessons,meanwhile,someinformationofhowtousetheresourcesinthelibraryorontheinternetwillbegained.WhatisthemostessentialisthatmyacademicknowledgeisnotsobroadasIchangedmymajorfromMicroelectronics（Undergraduate）toCommunicationEngineering（Postgraduate）,soIneedtochosethisprojecttoenrichmyknowledgethroughreadingseveralacademicjournalsandbooks.

1.2Backgroundinformationaboutcommunicationtechnologiesinhistory

Intheancientworld,communicationreferstothetransmissionofmessagesfromoneplacetotheotheranditsaimissendinginformation.Peopleusedtosendmessagesbyhorse,pigeon,semaphore,beaconsorengravingonstonepillars.Thesecanbesubdividedintotwocategories:

opticaldeliveryandnon-opticaldelivery.Opticaldeliverycontainsseveralmethodssuchasfirealarm,beacon,bodylanguage,whilenon-opticaldeliveryreferstotheconveyanceofinformationbyengravingonstonepillarsorsendingletterswhicharetransferredbyhorseandpigeon.（BamberGascoigne,1993）

Thecommunicationtechnologiesintheancientworldwereinefficient,especiallywhenthetraveldistancewasremoteandittakesmonthsorevenyearstosendalettertoothers.However,withthedevelopmentofmoderntechnologies,peoples’requestsonquickcontactresultedintheinvestmentofseveralnewcommunicationtechnologiessuchasTelecommunications.AccordingOxfordDictionaries（2013）andMerriam-WebsterDictionaries（2013）,Telecommunicationsrefertothetransmissionofdata,telephone,radioandsoonfromoneplacetotheotherbyusingtechnologicalmethods（electricalsignalsandelectromagneticwaves）.Alsothistechnologyhasseveraluniquecharacteristicssuchasthesignalswillnotbeinfluencedbytime,distanceandplace,whichimplicatesitcanprovidepeoplewitharapid,accurate,reliablecontactingmode.Duetoitsuniquefeatures,Telecommunicationsaredevelopingrapidlyandbeingwidelyused.

Itmustbepointedoutthatitiscommunicationtechnologiesshortenedthedistancebetweendifferentcountries,increasedtheefficiencyofeconomicandchangedpeople’slivingstylesgreatly.

1.3Anoverviewofcommunicationtechnologiesfrom1Gto3G

Thedevelopmentofmoderncommunicationcanbesubdividedintosixmainperiodsasfollows.Firstly,intheperiodsfrom1920to1940,communicationtechnologiesexperiencedaninitialdevelopment.Forexample,accordingtoRegisJ.B.（2007）,carphoneradiosystemwasfirstequippedintheStLouispoliceonJunethe17th1946beforeitwaswidelyusedinNorthAmericainthe1980s.Inthenexttwentyyears,thetelephonenetwork,whichwasfirstestablishedbyBillSystemequippedinpublicvehiclesaroundtheworld,whichimplicatedapublicusedmobilecommunicationservicehadappeared.ThenAmericanrealizedautomatictuningandautomaticconnectionfrom1960to1970.AccordingtoW.RaeYoung（1979）,BillLabinventedandrealizedtheAdvancedMobilePhoneSystemthatcanbeseenasthefirstgeneration.ItalsomeansaCellularMobileCommunicationNetworkwasestablished.OnthebasisofNetworks&Communications（2005）,theUKhaddevelopedanothercommunicationsystemcalledTACSwhichwasusedintheUKandIrelandin1983.Afterthat,itcanbeseenfromVijayK.G.（2002）,inaround1982,EuropeputforwardaGlobalSystemforMobileCommunicationsSystem（GSM）,whichhadbeenwidelyusedinmostEuropeancountriesintheworldasitcouldimprovethevoicequalityandincreasethenetworksecurity.Lastly,accordingtoPatilC.S.（2012）,attheendof20thcentury,AsiaandEuropepointedoutanewcommunicationsystemcalledW-CDMA,whileAmericanlaunchedCDMA2000.Thesetwosystemscannotonlytransmitvoice,butalsotransmitdigitalinformation,whichcouldprovidecitizenswithamoreconvenientandeasieraccesstowirelessapplications.

2TheFirstGeneration

2.1Definitionofthe1stGeneration

Thereisnotanaccuratedefinitionofthe1stGeneration.However,accordingtoGeography-dictionary（2008）,YourDictionary（2013）andPatilC.S.（2012）,thefirstGenerationreferstotheCellularMobileCommunicationnetworkwhichmakesuseofanalogueradiotechnologies.

2.2The1stGeneration

TheFirstGenerationcellulartechnologyisbasedonFDMA（frequencydivisionmultipleaccess）whichcandividethecommunicationbandintodifferentchannels.Eachofthemcouldbeappliedtotransmitdigitaldataproducedbyonecertainconversationonthemobilephonethatmeansthecellularsystemprovidesspecialfrequencyfordifferentuser.

AccordingtoPatilC.S.（2012）,theFirstGenerationcellulartechnologysuchasAMPSofferedaspecialfrequencytoeachcustomer,sowiththerisingnumberofusers,thebandwidthshouldincreaseeither.Thatistosay,theefficiencyofthetransmissionbetweencellcentreandusersislow.Also,ithasnosecuritymethodtopreventtheconversationfrombeingeavesdroppedbycriminals.AccordingtoJamesGuyton（2000）,comparedwith2Gand3G,theFirstGenerationhasalowerfrequencyandalongerwavelength,whichmeansitalsohasahigherrateofbeinginterferedbythenoise.

Accordingtotheopinionsmentionedabove,differentideascanbeseenfromthreeauthors.DissimilarfromJamesG.,PatilC.S.（2012）isfocusingonthefieldsofcustomers.Ittoldusthat1Gcannotsatisfygeneralpeople’sdesireasitcouldnotcontinueworkingwhenthenumberofcustomersisenormous.PatilC.S.comparedtheanaloguetechnologywiththedigitaloneinthefieldsofefficiencyandsecurity.SimilarwithPatilC.S.,JamesG.alsocomparedtheoldtechnology（1G）withtheadvancedtechnology（2Gand3G）intheareaofnoisecancelling.Thoroughseveraldisadvantagesofthe1stGenerationarepresentedcouldimplicate1Gmustbereplacedbyothersystem,someadvantagesofitshouldnotbeneglected.Forinstance,1Gisthefirstsuccessfulstandardnetworktechnology.Comparedtoearliertechnologieswhichreliesonwiredconnectiontomaketelephonecalls,1Gprovidesuserswitharealfreedomandmobility,whichensurethemcommunicatewiththeotherswhileintheoutside.Also,withthehelpof1G,theefficiencyofmilitaryactions,scientificresearchesandcommercialexchangeascendedquitealot.

3TheSecondGerneration

3.1Definitionofthe2edGeneration

AccordingtoMotorolasolutions（2013）,OxifordDictionary（2013）,PatilC.S.（2012）,andJamesG.（2000）,theSecondGenerationreferstocommunicationtechnologiesbasedonthedigitalmobilecommunicationsstandardordigitalmodulationtechnology.

3.2The2edGeneration

Comparedwiththe1Gbasedonanaloguetechnologywhichcanonlytransfervoice,theSecond-generationwirelesstelephonetechnologyisonthebasisofdigitaltechnologiesenablingthetransmissionofvoiceanddigitaldata.SystembasedonthedigitaltechnologyConvertedthefigure,text,soundintobinarycodewhichcanbetransferredtotheothersystemthoughseveralprocedurelikeprocessingcompressing,decodingandsoon.

AccordingtoMotorolasolutions（2013）,the2edGenerationlaunchedinthe1990sthatcanbedividedintoaroundfivecategoriesincludingGSM,PCS,IDEN,TDMAandCDMA.Thismobiletechnologyimprovedsignificantlyincomparisontothepriortechnology,e.g.theprioronecanonlysentvoiceinformationbutthefollowingtechniqueenablethetramsmissionofshortmessage（SMS）.PatilC.S.（2012）statesthatthesystemof2Gisoverthreetimesthecapabilityof3Ganditprovidesamoreefficienttransmissionprocess.However,itsabilityofviewinglargewebsiteandsendingemailneedtobeimproved.IntheviewofJamesG.（2000）,theSecondGenerationtechnologyensureabettersecurityenvironmentwhenmakephonecallstotheotherandalongercelllife.HealsopointsoutthatthethreemaintypesintheworldareTDMA,GSMandCDMA.

Accordingtotheopinionsmentionedabove,differentideascanbeseenfromthreeauthors.AsimilaropinioncanbeseenfromJamesG.andPatilC.S..ThatisthespeedofsearchingtheInternetisnotsatisfying,whichcouldinduceaninefficienttransmissionofemail.Anotherauthorjustconcentratesonthebenefitsof2Gsuchasitenablespeopletosendshortmessagestotheotherbutnotmentioningitsdefects.ThroughtheSecondGenerationissuccessfulinmostcountriesintheworldanditisstillwildlyusedinseveralregions,somedefectsimplicatedthatitneedsdevelopmentsinthefieldsofstandardunificationandlengtheningthebandwidth.

4TheThirdGeneration

4.1Definitionofthe3rdGeneration

TheThirdGenerationisthethirdgenerationofmobilecommunicationstandardregulatedbyITU（InternationalTelephoneUnion）.The3rdGenerationisfocusingonprovidingpeoplewithfastinternetaccessandmultimediaservicewithwhichpeopleca