AbstractFromtheconceptofthenetworkuniversity,wededuceitsthreebasicinfrastructures：theeducationcenterstation,thehighspeedbackboneandtheuserterminalnetwork.wepointoutthattheremotelearningonlineathomewillbethemostimportantstudyingmodelinthefuture，sotheHomeNetwillbeanecessaryinfrastructureplatformforremotelearning,inthispaperwediscussthestructure,thekeytechnologiesandconnectionmediaofHomeNet.
KeywordsnetworkuniversityremotelearningHomeNet
1．TheBackground
Withtheextensionofinternetinapplicationarea,fromacademies,enterprisestothegovernmentdepartments,thenetworkreachesvariableaspectsofoursociety.Fromknowledgelearning,messageobtainingtoe-commerce,thedigitalnetworkisallprovedastrongpushingstrength.Withnetwork,thedifferenceoftimeandspaceareeliminated,theexchangeandcommunicationamongpeople,theresourcessharingarebecomingmuchmoreeasier,basedonthat,moreandmoreapplicationsaredeveloped,andoneofwhichisthenetworkuniversityandremotelearningwhichwillbeagreatrevolutiontothetraditionalteachingandlearningway.Peoplecanstudyonline,exchangethoughtsinteractivelywithteachersandschoolmatesthroughnetworkratherthanspecialclassroomsinthecampus,thiswillprovideachancetolearnknowledgeallthelifeforthosewhoareinworkorcan’tgointocolleges,perhapsthenetworkuniversitywillbethemostimportantmodeltostudyinanotlongfuture.
Thenetworkuniversityconsistsofthreeinfrastructures:theeducationcenterstationswhichincludemultimediacourseware,soundandimagematerialetc.,thehighspeedbackboneanduserterminalnetwork.Ourgovernmenthasmadetheremotelearningastrategytopromotethequalityofthenation,theCERNET2.5GBPSbackboneareinconstruction,andtheeducationcenterstationshavealreadybeenimplementedsuccessfullyinsomecampuses,sothekeytoemployingtheremotelearningprojectliesinthethirdpart---theuserterminalnetwork.
Thenetworkbringsusgreatflexibilitytostudyonline,nodoubt,themostoftenplaceforpeopletolearnisathome,andwiththedevelopmentoflifestandard,manyfamilieswillhavemorethanonesetofcomputerandHDTVsets,andstudyisnotonlythethingofchildren,butalsotheneedofparents,andadditionally,remotemedicaltreatment,orderingonline,homeautomationcontrollingareallthefuturerequirementsinthefamily[1],soitisanecessaryconditiontodigitalizedthefamiliesintheinformationsocietytoconstructaperfectHomeNet(hometerminalnetwork)whichprovideallabovefunctions,inthefollowingsections,wewilldiscussthestructure,thekeytechnologiesandaccessmediaofHomeNet.
2.TheKeyTechnologiesinHomeNet
ThehomenetworkisaspecialLAN,inlogicalstructure,theyhavesomeresemblance,butthehomenetworkhasitsownspecialfeaturesinapplicationenvironment,operationalfunctionsandsystemphysicalconstruction.Theimplementofhomenetworkrequiresseveralkeytechnologiestosupportasfollowing[2]:theembodiedoperatesystemandembodiedcustomIC(ASIC),APIlevelinteroperablespecifications,thefinaluseinterfacedesignandaccesstechnology.
2.1Therearevariousdevicesathome,andthedifferencebetweenthemislargeincontrollingmodel,computationabilityandintelligentlevel.Mostofthemarelessperformanceproductsexceptafewsuchascomputers,thus,toenablethewholehomenetwork,theembodiedOSandICisthekerneltechnologies.CurrentprevailingembodiedOSareWINDOWSCE,3COMPalmOS,JAVA2,JAVA2MicroEdition,Pjava,EjavaandourownembodiedHopenOSdesignedbyKAISICooperation.TheembodiedICincludesLonWorks’NeuronICsandIntel’smicrocontrollerssuchas8051familyandthelike.
2.2APIisapplicationprograminterface,duetothemediaisvariousinthenetworkphysicallayer,inordertogettheinteroperabilityontheprograminterfacelayer,APIleverinteroperablespecificationsmustbedefined,it’sthefoundationtodevelophomenetworkapplication,itshieldstheunderlayerprotocols,andprovideaidenticalinterfacetoapplicationdeveloper.ThecurrentAPIsareMicrosoftUPnP,SUNJINI,HomePNP,HomeAPIandsoon.
2.3Userinterface(UI)determinestheeasydegreeofoperation,andthenbringaboutthesystem’sfinaluserecognition.TotheHOMENETinterface,itsapplicationenvironmentandspecialuseobjectsdecidethefollowingfeatures[3]:
Usability:theusersofhomenetworkarevariouspeople,theage’sdisparityfromyoungtoold,theculturelevelandrelativetechnologyisdifferentfromeachother,sotheusabilityofHomeNetisveryimportanttodevelopthehomenetworkmarket,thustheUImustprovideaflexible,simpleandintuitionalinterfacetothegeneralusercollective.
Mobility:HomeNetisaheterogenousnetwork,itconsistsofdigitalsubnetwork,A/Vsubnetworkandcontrolsubnetwork.WhenalltheelectronicsathomeareconnectedbyHOMENET,usersshouldconfigure,control,manageandcheckthenetworkperformanceandequipmentstatusfromdifferentaccesspoints.
Scalability:Duetotheeconomics,technologyandmarketelements,theprocessofHOMENETconstructionisnotaninstantprocedure,butisaaccumulatingone,sothetopologystructuremustfacilitatethesystemupgradeandmaintenance,andtheUIshouldprovidetheproperinterfacetothenewpluggedequipment.
2.4AccesssectionistheconnectionbetweeninternetandHomeNet,accesstechnologycanbespanidedintotwotypes:wireandwirelessways,thewirewayincludesModem,HFC/CableModem,FFTHandxDSLtechnologies,thewirelesswayincludesWAP,LDMSandsoon.TraditionalModemtechnologyhaslowtransmissionrate,withthehomenetworkwidespreads,theaccesstechnologywilltransfertoCableModemandxDSLtechnology,andintheend,theFTTHandWAPtechnologywillbethepreferselection.
3.HomeNetLogicalLayerArchitecture
Figure1showstheHOMENETlogicalarchitecture,thewholesystemconsistsoffivelayers:physicalmedialayer,protocollayer,APIlayer,APPlayer(applicationprogram)andUI(userinterface)layer.Thespecificationsoftheunderlyingtwolayershasbeendistributedandusedinpractices.
Figure1HomeNetarchitecture
TheAPIlayeristhekeyofHomeNet,thetechnologiesofitisthehotissueofhomenetworkdevelopment,theHomeAPIandJinispecificationsdistributedin1999.ThefourthlayerAPPisasetofapplicationsoverthethird.ThefifthlayerisUI,itisasetofvariousinterfacetools,itisnotlimitedtoPC,butalsoincludesemergentbuttons,helpswitches,remotecontrollingdevicesandothervisualinterfaces.
TheHomeNetprotocolscanbespanidedintothreetypes:underlayerprotocols(media,protocollayers),APIprotocolsandUIspecifications.InUIlayer,withoutproperdistributedspecifications,withthemarketenlargingandtheincrementofuserrequirement,itisnecessarytostandardizetheUIdesign.Fromtheviewofzone,theHomeNetspecificationsaredistributedbyAmerica,EuropeandJapan,suchasJapan’sHBS,Europe’sBatiBUS,EuropeHomeSystemandEIB,America’sX10,CEBusandlonWorks.Addition,someworkgroupalsodistributedspecificationssuchasHAVI’sIEEE1394,Bluetooth,HPNP,HomeAPIandJini[4][5].
4.TheConnectScenariosandMedia
Thereareseveralcommunicationmediaathomeasfollowing:TP(twistedpair),TL(telephoneline),xDSL,CableModem,FB(fiber),PL(powerline)andwirelesstrsmission(IEEE802.11,HomeRF,Bluetooth).TP,TLandPLarecurrentprevailingmediainHomeNet,FB,xDSL,CableModemandwirelessmediawilldominateinthefuture.
Theimplementofconnectionscenariosarerelativecloselytothecommunicationmedia.ThetworulesmustbeobservedinHOMENETconstruction,thefirstistheusabilityandtheanotheristhereasonablecost.DuetoHOMENET’Svariousfunctionsandeachfamily’saffordingability,theconnectionscenarioswillalsobevarious.Inthefollowingsections,wediscussetherandfastethernetwork,homeTLnetwork,PLnetworkandwirelessnetwork.
Etherandfastethernetwork:ethernetworkisoftenusedinpractice,simplicityandreliabilityisitsadvantage,andthecostislowerthanotherscenarios.Thecompatibilityofitmakesitconvenienttoupgradefrom10mpbsto100mpbsand1000mpbsethernetwork,anditbenefitsusersfromprotectingtheoriginalinvestigates,sothisisapreferredscenarioinconstructingHomeNet.
TLHomeNet:HomeTLtechnologymakesitpossibletobuildahighspeednetworkathomebyusealreadyexistingtelephonelines.The10mpbsTLspecificationhasbeendistributedinHomePNA2.0,adigitalproductcanbeeasilylinkedtothenetworkbyainterfacemodulewhichconnectsthetelephonelineplugandtheproduct.Addition,thexDSLtechnologyextendsthePLcommunicationband,andmakestheTLHOMENETcanaffordthemultimediaapplications.
PLnetwork:thisscenariointerconnectsthehomedigitaldevicesbyubiquitouspowerlines,itsbiggestadvantageisthatmostoftheelectronicproductshavebeenlinkedtoPLs.AlthoughtheoldPLnetwork(X-10)havedifficultiestocarryhighspeeddatainformation,thenewtechnologyhasimplementedhighspeeddatatransmission.
Wirelessnetwork:theadvantagesofitoverwirenetworklieinflexibility,mobilityandeasyconstructing.Thetechnologymaturityofthewirelessnetworkhasbeenprovedintheapplicationsofrestaurantcommunicationandstockexchangeinformationtransmission,butthedefectisitshighcostinconstructionandthenarrowcommunicationband.Withtheappearingofnewtechnologies,thewirelessnetworkwilldominatetheHomeNetmarketinthefutureduetoitsabovetributes.
5.TheEnd
Therearestillalotthingstodotospreadthehomenetworkcurrently:firstofallisthedevelopmentofembodiedOSandIC,thenwithouttheinteroperablespecificationsthedifferentdevicescannotcommunicateeachotherdirectly,andtheintegrationofHomeNetbecomescomplicatedduetomuchmoreprotocolsintheunderlays,somucheffortsshouldbetakentoimplementthedreamofremotelearningonline,orderingonlineandsoonthroughtheHomeNet.
References
[1]MAURYWRIGHT:"Home-automationNetworksmaturewhilethePCindustrychasesanewhomeLAN",EDNJUNE4,1998.
[2]Zhongxichang,HomedigitaldevicesPCWORLDCHINA,JAN3,2000NO.1
[3]Caojiuxinect.,TheTechnologyandDesignStrategyofHomeNetUserInterfaceMINI-MICROSYSTEM,2000
[4]HomeAutomationNetworkStandardsandSpecs–AlliancesandWorkingGroups.http://www.hometoys.com
[5]KennethP.Wacs,PH.D.IntroductiontotheCEBUS®communicationsprotocol.HTINewsArticles1999
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