校园无线网路技术与应用发展英文版

校园无线网路技术与应用发展英文版Outline無線區域網路─無線應用通訊協定─WAP3/20/20232無線區域網路通訊協定WirelessLocalAreaNetwork(IEEE802.11)3/20/20233無線區域網路標準SpecifiesasingleMediumAccessControl(MAC)sublayerand3PhysicalLayerSpecifications.Stationscanoperateintwoconfigurations:Ad-hocmodeInfrastructuremodeThreePHYspecificationsFrequencyHoppingSpreadSpectrum(FHSS).DirectSequenceSpreadSpectrum(DSSS).InfraredPHY.3/20/20234規範IEEEProject802Charter:Local&MetropolitanAreaNetwork1Mbpsto100Mbpsandhigher2lowerlayersof7LayerOSIReferenceModelIEEE802.11WorkingGroupscope:Wirelessconnectivityforfixed,portableandmovingstationswithinalimitedareaAppeartohigherlayer(LLC)thesameasexisting802standardsApplicationLayerNetworkLayerMACPhysicalLayer...LLCIEEE802.11DataLinkLayer3/20/202351997/6/26通過成為IEEE802系列標準架構MediaAccessControlLogicalLinkControlInfraredPhysicalLayerFHSSPhysicalLayerDSSSPhysicalLayer3/20/20236AdHoc網路OneBasicServiceSetDirectedConnectionLimitedCoverageArea3/20/20237APBSSInfrastructure網路APBasicServiceSetExistingWiredLANDistributionSystemOtherLANsExtendServiceSet3/20/20238Infrastructure網路(cont.)AccessPointandMobileStationDistributedSystemInterconnectMultipleCellsviaAccessPointstoformasinglenetworkExtendsWirelessCoverageAreaMultipleBasicServiceSetsconnectedtogetherformanExtendedServiceSetAllowMobileStationtoaccessfixedresourceSupportRoamingforMobileStationsviaAccessPointPointCoordinationFunction,PowerManagement,TimeSynchronizationsupportthroughAccessPoint3/20/20239IEEE802.11ServicesProvidesserviceswiththefollowingfunctionality:roamingwithinaESS,multipledataratesinBSSsandPowerManagement.TheMACprotocolisCarrierSenseMultipleAccesswithCollisionAvoidance(CSMA/CA)MACservicesAssociationserviceAuthenticationserviceDistributionserviceIntegrationserviceDeauthentication/Deassociationservice3/20/202310SpreadSpectrumTechnologyDSSS（DirectSequenceSpreadSpectrum）11channelsPN-code長度為11-bit展頻寬度為11MHzFHSS（FrequencyHoppingSpreadSpectrum）78hopsequences頻帶範圍為1MHz，跳頻的頻率為每秒次InfraredRay發展趨勢：DHSS往高速無線區域網路系統發展，適合辦公室環境使用；FHSS會往低價網路應用發展，提供SOHO及家庭應用、或周邊設備之無線網路連結。3/20/202311直接序列展頻（DSSS）3/20/202312跳頻展頻（FHSS）3/20/202313IEEE802.11TGaTheTGaisworkingonthehighdata-rateextensioninthe5GHzband,project802.11a,wasabletoproduceanewdraftstandardthathasthesupportofatleast80%ofthemembers.TGaislookingatacandidateforworldwidestandardization!3/20/202314IEEE802.11TGa(cont.)ThespecificationsofthePhysicalLayerencompassdataratesfrom6Mbit/supto54Mbit/s,with20MHzspacingbetweenadjacentchannels.Allimplementationsarerequiredtosupport6,12and24Mbit/s.Optionalextensionsarefor9,18,36,48and54Mbit/s.Themulti-ratemechanismoftheMACprotocolensuresthatalldevicescommunicatewitheachotheratthebestdatarateinthepresentchannel.3/20/202315IEEE802.11TGbTheTGbisworkingontheextensionofthe1and2Mbit/sdataratesinthe2.45GHzbandwith5.5and11Mbit/shasreachedatechnicalcompromisesolutiontoimprovetheco-existenceandinteroperabilitycharacteristicsbetweenoptions.Themulti-ratemechanismwarrantsthatthe11Mbit/s3/20/202316CSMA/CD(LAN)Senddataifthemediumissensed“idle”Ifcollideswithotherhost(s), thenbackoffforarandomnumberoftimesRe-senddatalater3/20/202317HiddenTerminalProblemBACdatadata3/20/202318SolutiontoHTPBACRequestGrant3/20/202319DetectionofCollisionBACRequestRequest3/20/202320BACRequestAisGrantAisGrantDCollisionAvoidance3/20/202321RTS/CTS/data/ACKandNAVsetting3/20/202322SomeIFSrelationshipsandbasicaccessmethod3/20/202323RandombackofftimeBackofftime=INT(CW*Random())*aSlotTimeINT(x):小於或等於x的最大整數CW(contentionwindowparameter):介於CWmin和Cwmax間的整數,CW依序遞增的順序為(7,15,31,63,127,255,255,255……)Random():介於0到1間的實數aSlotTime:傳送器開啟延遲+媒介傳遞延遲+媒介忙碌偵測反應時間3/20/202324AnexampleofexponentialincreaseofCW3/20/202325Backoffprocedure3/20/202326Transmissionofamulti-fragmentMPDUusingSIFS3/20/202327RTS/CTSwithfragmentedMSDU3/20/202328RTS/CTSwithtransmitterpriorityandmissedacknowledgment3/20/202329Directdata/ACKMPDU3/20/202330無線區域網路軟體技術架構WLANPlatformEmbeddedControlSoftwareWLANManagementUtilityNetworkApplicationsDSSSFHSSMediaAccessControlNetworkDriver(NDIS)SocketInterfaceMobileIPSNMPAgentSecurityDistributedServiceE-MailFileTransferRemoteAccessMobileDataDECTU-NIIorISMbandETSI3/20/202331無線應用通訊協定WirelessApplicationProtocol(WAP)3/20/202332無線上網趨勢日本NTT的DoCoMo

於2/1999推出無線上網服務，一年內累積3百萬用戶，每週增加10萬人WAPForum於1997年成立，至1999年12月全世界有200家無線通訊事業成為會員(95%市場之相關業者投入)1999年，WAP是手機使用者最熱門話題之一3/20/202333無線上網趨勢(續)1999年在台灣銷售180萬隻手機前兩大廠─Motorola於2000上半年WAP手機佔40%，下半年100%投入；Nokia則佔30%。國內新上市的手機六到七成內建WAP功能台灣已超過1000萬人有行動手機，而PC上網人數約3至4百萬語音：數據─95%:5%(2000);40%:60%(2005)3/20/202334全球無線通訊用戶成長3/20/202335預估未來WAP手機的佔有率3/20/2023363/20/2023373/20/202338手持型元件之延革3/20/2023393/20/202340bringtheinternetcontentandadvancedservicesto後PC時代之userscreateaglobalwirelessprotocoltoworkacrossdifferingwirelessnetworktechnologiesenableapplicationstoscaleacrossavarietyoftransportoptionsanddevicetypesWhat’sWAPfor?3/20/202341WhatisdefinedinWAP?Micro-BrowserScriptingtoenhanceMScapabilitiesWTA/WTAIfortelephonefunctionality(e.g.callchains)ContentFormatsbusinesscard(vCard)calendarevent(vCalendar)LayeredTelecommunicationStack3/20/202342Comparison3/20/2023433/20/202344GoalsforWTP(WAPv1.1)acommoninterfacetophysicaltransportmechanismsprovideaport-basedabstractinterfacetoupperlayerprotocolsallowapplicationsdesignedindependentfromspecifictransportsextensibletoavarietyofdigitalwirelessnetworksandfuturetransportoptions3/20/202345GoalsforWTP(cont.)supportsconnection-oriented,transaction,anddatagrammodesoptimizefornarrowtomediumbandwidthchannelstobecapableofimplementationinalowmemoryfootprint,suitableforstandardorlow-IQhandsets3/20/202346RequirementsforWTPWTP/Cprovidesareliableconnection-orientedservicetotheupperlayerWTP/Tprovidesareliabletransaction-orientedservicesuitableforwebbrowsingWTP/Dprovidesadatagramservicelightweight:implementablein<=10Kb(lowmemory/computationalneeds)3/20/202347WTP/Dfeatures

(WDPinWAPv1.2)WTP/D(Datagram)providesaconnection-less,unreliabledatagramserviceWTP/DisreplacedbyUDPwhenusedoveranIPnetworklayer.usestheServicePrimitiveT-UnitData.req.ind3/20/202348WirelessBearers:SMSUSSDCSDIS-136CDMAIDENCDPDPDC-PGPRSWirelessApplicationEnvironment(WAE)WirelessSessionProtocol(WSP)WirelessTransactionProtocol(WTP)WirelessTransportLayerSecurity(WTLS)Datagrams(UDP/IP)Datagrams(WDP)OtherServicesandApplicationsWirelessBearers:SMSUSSDCSDIS-136CDMAIDENCDPDPDC-PGPRSWirelessApplicationEnvironment(WAE)WirelessSessionProtocol(WSP)WirelessTransactionProtocol(WTP)WirelessTransportLayerSecurity(WTLS)Datagrams(UDP/IP)Datagrams(WDP)OtherServicesandApplications3/20/202349WTP/Tfeatures

(WTPinWAPv1.2)

WTP/T(Transaction)providesreliabledatatransferbasedonrequest/replyparadigmnoexplicitconnectionsetuporteardowndatacarriedinfirstpacketofprotocolexchangeseekstoreduce3-wayhandshakeoninitialrequest3/20/202350WTP/Tfeatures(cont.)

supportsretransmissionoflostpacketsselective-retransmissionsegmentation/re-assemblyportnumberaddressing(specifictoWTP/T)flowcontrolmessageoriented(notstream)supportsanAbortfunctionforoutstandingrequests3/20/202351WirelessSessionProtocol

WSP/BprovidesupperlayerswithsessionservicesandmanagementWSPprovidesmeansto:establishareliablesessionfromclienttoserveragreeoncommonlevelofprotocolfunctionalitybycapabilitynegotiationcompactencodingsuspendandresume3/20/202352WSPfeaturesHTTP1.1functionalityExchangeofclientandserversessionheadersInterruptmechanismfortransactionsinprocessContentPushfromservertoclientNegotiationformultiple,simultaneousasynchronoustransactions3/20/202353WTLSRecordProtocol

4recordprotocolclients:ThehandshakeprotocolThechangecipherspecprotocolThealertprotocolTheapplicationdataprotocolWTLSconnectionstate:theoperatingenvironmentforrecordprotocolcompression/encryptionalgorithmMACalgorithm--keys3/20/202354RecordProtocolUsage

HandshakeprotocolNegotiatesecureattributesofasecuresessionauthentication,securityparametersettingsChangecipherspecprotocolSignaltransitionsincipheringstrategiessentbeforeverifyingfinishedmessageAlertprotocolconveytheseverityofthemessageandadescriptionofthealert3/20/202355WirelessApplicationEnvironment

(WAE)

AnInternet(WWW)programmingmodel

Vendor-controlledMMIInitialfocusonphonesSlowbearersSmallmemoryLimitedCPUSmallscreenLimitedinputmodel3/20/202356WAEComponentsArchitecture–Applicationmodel–Browser,Gateway,ContentServerWML(WirelessMarkupLanguage)–DisplaylanguageWMLScript–ScriptinglanguageContentFormats–Dataexchange3/20/202357WAEIn-DeviceArchitecture3/20/202358WML

Tag-basedbrowsinglanguage:Screenmanagement(text,images)Datainput(text,selectionlists,etc.)Hyperlinks&navigationsupportSyntax:W3CXML(SGMLderivative)InheritstechnologyfromHDMLandHTML3/20/202359WML(cont.)

CardmetaphorUserinteractionsaresplitintocardsNavigationoccursbetweencardsStatemanagementandvariablesReducenetworktrafficResultsinbettercachingExplicitinter-cardnavigationmodelHyperlinksUIEventhandlingHistory3/20/202360WMLExample

<?xmlversion="1.0"?><!DOCTYPEwmlPUBLIC"-//WAPFORUM//DTDWML1.1//EN"":///DTD/wml_1.1.xml"><wml> <cardid="main"> <dotype="accept"> <gohref="#ecard"/> </do> <p>Welcome!</p> </card> <cardid="ecard"> <dotype="accept"> <gohref="#ecardN=$(N);S=$(S)"/> </do> <p> Entername:<inputname="N"/> speed: <selectname="S"> <optionvalue="0">Fast</option> <optionvalue="1">Slow</option> </select> </p> </card></wml>3/20/202361WMLScript

Scriptinglanguage:Procedurallogic,loops