通信专业英语自选课文.docx
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通信专业英语自选课文.docx
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通信专业英语自选课文
Lesson1InternetofThings
Incomputing,theInternetofThingsreferstoanetworkofobjects,suchashouseholdappliances.Itisoftenaself-configuringwirelessnetwork.TheconceptoftheinternetofthingsisattributedtotheoriginalAuto-IDCenter,foundedin1999andbasedatthetimeinMIT[1].
Theideaisassimpleasitsapplicationisdifficult.Ifallcans,books,shoesorpartsofcarsareequippedwithminusculeidentifyingdevices,dailylifeonourplanetwillundergoatransformation.Thingslikerunningoutofstockorwastedproductswillnolongerexistaswewillknowexactlywhatisbeingconsumedontheothersideoftheglobe.Theftwillbeathingofthepastaswewillknowwhereaproductisatalltimes.Thesameappliestoparcelslostinthepost.
Ifallobjectsofdailylife,fromyogurttoanairplane,areequippedwithradiotags,theycanbeidentifiedandmanagedbycomputersinthesamewayhumanscan.[2]ThenextgenerationofInternetapplications(IPv6protocol)wouldbeabletoidentifymoreobjectsthanIPv4,whichiscurrentlyinuse.Thissystemwouldthereforebeabletoinstantaneouslyidentifyanykindofobject.[3]
TheInternetofobjectsshouldencode50to100,000billionobjectsandfollowthemovementofthoseobjects.Everyhumanbeingissurroundedby1,000to5,000objects.[4]
Alcatel-Lucenttouchatag[5]serviceandViolet'sMirrorgadgetprovideapragmaticconsumerorientedapproachtotheInternetofThingsbywhichanyonecaneasilylinkrealworlditemstotheonlineworldusingRFIDtags(andQRCodesincaseoftouchatag).
Universaladdressabilityofdumbthings
Analternativeview,fromtheworldoftheSemanticWeb[6]focusesinsteadonmakingall"things"(notjustthoseelectronic,smart,orRFID-enabled)addressablebytheexistingnamingprotocols,suchasURI.Theobjectsthemselvesdonotconverse,buttheymaynowbereferredtobyotheragents,suchaspowerfulcentralisedserversactingfortheirhumanowners.
Obviouslythesetwoapproachesconvergeasmoreobjectsbecomeprogressivelyaddressableandmoreintelligent.Thisisunlikelytohappeninanysituationshortofspime,andthetwoviewshavesignificantlydifferentimplicationsintheinterim.Inparticular,theuniversaladdressabilityapproachrapidlyincludesthingsthatcannothavecommunicationbehaviorsoftheirown,suchasabstractdatadocuments.
Trends,Characteristics
TheInternetofThingswilllikelybea"nondeterministic"andopennetwork(cyberspace?
)inwhichauto-organizedorintelligententities(Webservices,SOAcomponents),virtualobjects(avatars)willbeinteroperableandabletoactindependently(pursuingtheirownobjectivesorsharedones)dependingonthecontext,circumstancesorenvironments.ItwillhostAmbientintelligence(builtuponUbiquitouscomputing).
"Reallife"VSModel-drivenarchitecture
Itwillalsolikelybeeventdriven[7],bottom-upmade(basedonthecontextofprocessesandoperations,inreal-time)andwillconsideranysubsidiarylevel(seealso:
Event-drivenarchitecture).Therefore,modeldrivenandfunctionalapproacheswillcoexistwithnewonesabletotreatexceptionsandunusualevolutionofprocesses(Multi-agentsystems,B-ADSc,etc.).Actually,inthisinternet,themeaningofaneventwillnotnecessarybebasedon,eitheradeterministicorsyntacticmodelbutwillbebasedonthecontextoftheeventitself:
thiswillalsobeaSemanticWeb.Consequently,itwillnotnecessarilyneedcommonstandardsthatwouldnotbeabletoaddresseverycontextoruse:
someactors(services,components,avatars)willaccordinglybeself-referencedand,ifeverneeded,adaptivetoexistingcommonstandards(predictingeverythingwouldbenomorethandefininga"globalfinality"foreverythingthatisjustnotpossiblewithanyofthecurrenttop-downapproachesandstandardizations).
Chaoticorcomplexsystem ?
Insemi-openorclosedloops(i.e.valuechains,wheneveraglobalfinalitycanbesettled)itwillthereforebeconsideredandstudiedasaComplexsystemduetothehugeamountofdifferentandvariouslinks,interactions,betweenvarious,autonomousanddifferentactorsandduetoitscapacitytointegratenewactors.Attheoverallstage(fullopenloop)itwilllikelybeseenasachaoticenvironment(sincesystemshavealwaysfinality).
Timeconsiderations
InthisInternetofThings,madeofbillionsofparallelandsimultaneousevents,timewillnomorebeusedasacommonandlineardimension[8]butwilldependoneachentity(object,process,informationsystem,etc.).ThisInternetofThingswillbeaccordinglybasedonmassiveparallelITsystems(Parallelcomputing).
Notes
1.Dodson2003.TheAuto-IDCenterwasreplacedbytheAuto-IDLabsinOctober2003.Moreprecisely,EPCglobalwasformedasthesuccessororganizationtotheAuto-IDCenter,whileitssisterorganizationAuto-IDLabsmanagesandfundsresearchontheEPCtechnology.
2.CommissionoftheEuropeanCommunities(2009-06-18)."InternetofThings—AnactionplanforEurope"(pdf).http:
//ec.europa.eu/information_society/policy/rfid/documents/commiot2009.pdf.
3.Waldner2008.
4.Waldner2007
5.
6.DanBrickleyetal.,c.2001
7.PhilippeGAUTIER,« RFIDetacquisitiondedonnéesévènementielles :
retoursd'expériencechezBénédicta »,pages94à96,Systèmesd'InformationetManagement-revuetrimestrielleN°2Vol.12,2007,ISSN1260-4984/ISBN9782747212908,éditionsESKA.[1]
8.JanuszBucki,"L'organisationetletemps"(inFrench)
Lesson2WirelessNetwork
Wirelessnetworkreferstoanytypeofcomputernetworkthatiswireless,andiscommonlyassociatedwithatelecommunicationsnetworkwhoseinterconnectionsbetweennodesisimplementedwithouttheuseofwires.[1]Wirelesstelecommunicationsnetworksaregenerallyimplementedwithsometypeofremoteinformationtransmissionsystemthatuseselectromagneticwaves,suchasradiowaves,forthecarrierandthisimplementationusuallytakesplaceatthephysicallevelor"layer"ofthenetwork.[2]
Types
WirelessPAN
WirelessPersonalAreaNetworks(WPANs)interconnectdeviceswithinarelativelysmallarea,generallywithinreachofaperson.Forexample,BluetoothprovidesaWPANforinterconnectingaheadsettoalaptop.ZigBeealsosupportsWPANapplications.[3]
∙Wi-Fi:
Wi-Fiisincreasinglyusedasasynonymfor802.11WLANs,althoughitistechnicallyacertificationofinteroperabilitybetween802.11devices.
∙FixedWirelessData:
Thisimplementspointtopointlinksbetweencomputersornetworksattwolocations,oftenusingdedicatedmicrowaveorlaserbeamsoverlineofsightpaths.Itisoftenusedincitiestoconnectnetworksintwoormorebuildingswithoutphysicallywiringthebuildingstogether.
WirelessMAN
WirelessMetropolitanareanetworksareatypeofwirelessnetworkthatconnectsseveralWirelessLANs.
∙WiMAXisthetermusedtorefertowirelessMANsandiscoveredinIEEE802.16d/802.16e.
WirelessWAN
WirelessWideAreaNetworksarewirelessnetworksthattypicallycoverlargeoutdoorareas.Thesenetworkscanbeusedtoconnectbranchofficesofbusinessorasapublicinternetaccesssystem.Theyareusuallydeployedonthe2.4 GHzband.AtypicalsystemisaspertheonedeployedbyGaiacomWirelessNetworkscontainsbasestationgateways,accesspointsandwirelessbridgingrelays.Otherconfigurationsaremeshsystemswhereeachaccesspointactsasarelayalso.Whencombinedwithrenewableenergysystemssuchasphoto-voltaicsolarpanelsorwindsystemstheycanbestandalonesystems.
Mobiledevicesnetworks
Withthedevelopmentofsmartphones,cellulartelephonenetworksroutinelycarrydatainadditiontotelephoneconversations:
∙GlobalSystemforMobileCommunications(GSM):
TheGSMnetworkisdividedintothreemajorsystems:
theswitchingsystem,thebasestationsystem,andtheoperationandsupportsystem.Thecellphoneconnectstothebasesystemstationwhichthenconnectstotheoperationandsupportstation;itthenconnectstotheswitchingstationwherethecallistransferredtowhereitneedstogo.GSMisthemostcommonstandardandisusedforamajorityofcellphones.[4]
∙PersonalCommunicationsService(PCS):
PCSisaradiobandthatcanbeusedbymobilephonesinNorthAmericaandSouthAsia.SprinthappenedtobethefirstservicetosetupaPCS.
∙D-AMPS:
DigitalAdvancedMobilePhoneService,anupgradedversionofAMPS,isbeingphasedoutduetoadvancementintechnology.ThenewerGSMnetworksarereplacingtheoldersystem.
Seealsomobiletelecommunications.
Uses
WirelessnetworkshavehadasignificantimpactontheworldasfarbackasWorldWarII.Throughtheuseofwirelessnetworks,informationcouldbesentoverseasorbehindenemylineseasily,efficientlyandmorereliably.Sincethen,wirelessnetworkshavecontinuedtodevelopandtheiruseshavegrownsignificantly.Cellularphonesarepartofhugewirelessnetworksystems.Peopleusethesephonesdailytocommunicatewithoneanother.Sendinginformationoverseasispossiblethroughwirelessnetworksystemsusingsatellitesandothersignalstocommunicateacrosstheworld.Emergencyservicessuchasthepolicedepartmentutilizewirelessnetworkstocommunicateimportantinformationquickly.Peopleandbusinessesusewirelessnetworkstosendandsharedataquicklywhetheritbeinasmallofficebuildingoracrosstheworld.[5]
AnotherimportantuseforwirelessnetworksisasaninexpensiveandrapidwaytobeconnectedtotheInternetincountriesandregionswherethetelecominfrastructureispoororthereisalackofresources,asinmostdevelopingcountries.
Compatibilityissuesalsoarisewhendealingwithwirelessnetworks.Differentco
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