无线网路技术的应用

校園無線網路技術與應用發展Sheng-TzongCheng

鄭憲宗stcheng@.tw.tw06-2757575ext.625297/30/20231Outline無線區域網路─IEEE802.11無線應用通訊協定─WAP7/30/20232成大資訊鄭憲宗無線區域網路通訊協定WirelessLocalAreaNetwork(IEEE802.11)7/30/20233成大資訊鄭憲宗無線區域網路標準-IEEE802.11SpecifiesasingleMediumAccessControl(MAC)sublayerand3PhysicalLayerSpecifications.Stationscanoperateintwoconfigurations:Ad-hocmodeInfrastructuremodeThreePHYspecificationsFrequencyHoppingSpreadSpectrum(FHSS).DirectSequenceSpreadSpectrum(DSSS).InfraredPHY.7/30/20234成大資訊鄭憲宗IEEE802.11規範IEEEProject802Charter:Local&MetropolitanAreaNetwork1Mbpsto100Mbpsandhigher2lowerlayersof7LayerOSIReferenceModelIEEE802.11WorkingGroupscope:Wirelessconnectivityforfixed,portableandmovingstationswithinalimitedareaAppeartohigherlayer(LLC)thesameasexisting802standardsApplicationLayerNetworkLayerMACPhysicalLayer...LLCIEEE802.11DataLinkLayer7/30/20235成大資訊鄭憲宗1997/6/26通過成為IEEE802系列標準IEEE802.11架構MediaAccessControlLogicalLinkControlInfraredPhysicalLayerFHSSPhysicalLayerDSSSPhysicalLayer7/30/20236成大資訊鄭憲宗AdHoc網路OneBasicServiceSetDirectedConnectionLimitedCoverageArea7/30/20237成大資訊鄭憲宗APBSSInfrastructure網路APBasicServiceSetExistingWiredLANDistributionSystemOtherLANsExtendServiceSet7/30/20238成大資訊鄭憲宗Infrastructure網路(cont.)AccessPointandMobileStationDistributedSystemInterconnectMultipleCellsviaAccessPointstoformasinglenetworkExtendsWirelessCoverageAreaMultipleBasicServiceSetsconnectedtogetherformanExtendedServiceSetAllowMobileStationtoaccessfixedresourceSupportRoamingforMobileStationsviaAccessPointPointCoordinationFunction,PowerManagement,TimeSynchronizationsupportthroughAccessPoint7/30/20239成大資訊鄭憲宗IEEE802.11ServicesProvidesserviceswiththefollowingfunctionality:roamingwithinaESS,multipledataratesinBSSsandPowerManagement.TheMACprotocolisCarrierSenseMultipleAccesswithCollisionAvoidance(CSMA/CA)MACservicesAssociationserviceAuthenticationserviceDistributionserviceIntegrationserviceDeauthentication/Deassociationservice7/30/202310成大資訊鄭憲宗SpreadSpectrumTechnologyDSSS（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2.5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。7/30/202311成大資訊鄭憲宗直接序列展頻（DSSS）7/30/202312成大資訊鄭憲宗跳頻展頻（FHSS）7/30/202313成大資訊鄭憲宗IEEE802.11TGaTheTGaisworkingonthehighdata-rateextensioninthe5GHzband,project802.11a,wasabletoproduceanewdraftstandardthathasthesupportofatleast80%ofthemembers.TGaislookingatacandidateforworldwidestandardization!7/30/202314成大資訊鄭憲宗IEEE802.11TGa(cont.)ThespecificationsofthePhysicalLayerencompassdataratesfrom6Mbit/supto54Mbit/s,with20MHzspacingbetweenadjacentchannels.Allimplementationsarerequiredtosupport6,12and24Mbit/s.Optionalextensionsarefor9,18,36,48and54Mbit/s.Themulti-ratemechanismoftheMACprotocolensuresthatalldevicescommunicatewitheachotheratthebestdatarateinthepresentchannel.7/30/202315成大資訊鄭憲宗IEEE802.11TGbTheTGbisworkingontheextensionofthe1and2Mbit/sdataratesinthe2.45GHzbandwith5.5and11Mbit/shasreachedatechnicalcompromisesolutiontoimprovetheco-existenceandinteroperabilitycharacteristicsbetweenoptions.Themulti-ratemechanismwarrantsthatthe11Mbit/soperationcanswitchbackto5.5Mbit/s.Stationsthatareevenfurthercouldswitchbacktothe2and1Mbit/scapabilitiesoftheDSSSmodulation.7/30/202316成大資訊鄭憲宗CSMA/CD(LAN)Senddataifthemediumissensed“idle”Ifcollideswithotherhost(s), thenbackoffforarandomnumberoftimesRe-senddatalater7/30/202317成大資訊鄭憲宗HiddenTerminalProblemBACdatadata7/30/202318成大資訊鄭憲宗SolutiontoHTPBACRequestGrant7/30/202319成大資訊鄭憲宗DetectionofCollisionBACRequestRequest7/30/202320成大資訊鄭憲宗BACRequestAisGrantAisGrantDCollisionAvoidance7/30/202321成大資訊鄭憲宗RTS/CTS/data/ACKandNAVsetting7/30/202322成大資訊鄭憲宗SomeIFSrelationshipsandbasicaccessmethod7/30/202323成大資訊鄭憲宗RandombackofftimeBackofftime=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7/30/202324成大資訊鄭憲宗AnexampleofexponentialincreaseofCW7/30/202325成大資訊鄭憲宗Backoffprocedure7/30/202326成大資訊鄭憲宗Transmissionofamulti-fragmentMPDUusingSIFS7/30/202327成大資訊鄭憲宗RTS/CTSwithfragmentedMSDU7/30/202328成大資訊鄭憲宗RTS/CTSwithtransmitterpriorityandmissedacknowledgment7/30/202329成大資訊鄭憲宗Directdata/ACKMPDU7/30/202330成大資訊鄭憲宗無線區域網路軟體技術架構WLANPlatformEmbeddedControlSoftwareWLANManagementUtilityNetworkApplicationsDSSSFHSSMediaAccessControlNetworkDriver(NDIS)SocketInterfaceMobileIPSNMPAgentSecurityDistributedServiceE-MailFileTransferRemoteAccessMobileDataDECTU-NIIorISMbandETSI7/30/202331成大資訊鄭憲宗無線應用通訊協定WirelessApplicationProtocol(WAP)7/30/202332成大資訊鄭憲宗無線上網趨勢日本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一7/30/202333成大資訊鄭憲宗無線上網趨勢(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)7/30/202334成大資訊鄭憲宗全球無線通訊用戶成長7/30/202335成大資訊鄭憲宗預估未來WAP手機的佔有率7/30/202336成大資訊鄭憲宗7/30/202337成大資訊鄭憲宗7/30/202338成大資訊鄭憲宗手持型元件之延革7/30/202339成大資訊鄭憲宗7/30/202340成大資訊鄭憲宗bringtheinternetcontentandadvancedservicesto後PC時代之userscreateaglobalwirelessprotocoltoworkacrossdifferingwirelessnetworktechnologies

enableapplicationstoscaleacrossavarietyoftransportoptionsanddevicetypesWhat’sWAPfor?7/30/202341成大資訊鄭憲宗WhatisdefinedinWAP?Micro-BrowserScriptingtoenhanceMScapabilitiesWTA/WTAIfortelephonefunctionality(e.g.callchains)ContentFormatsbusinesscard(vCard)calendarevent(vCalendar)LayeredTelecommunicationStack7/30/202342成大資訊鄭憲宗Comparison7/30/202343成大資訊鄭憲宗7/30/202344成大資訊鄭憲宗GoalsforWTP(WAPv1.1)acommoninterfacetophysicaltransportmechanismsprovideaport-basedabstractinterfacetoupperlayerprotocolsallowapplicationsdesignedindependentfromspecifictransportsextensibletoavarietyofdigitalwirelessnetworksandfuturetransportoptions7/30/202345成大資訊鄭憲宗GoalsforWTP(cont.)supportsconnection-oriented,transaction,anddatagrammodesoptimizefornarrowtomediumbandwidthchannelstobecapableofimplementationinalowmemoryfootprint,suitableforstandardorlow-IQhandsets7/30/202346成大資訊鄭憲宗RequirementsforWTPWTP/Cprovidesareliableconnection-orientedservicetotheupperlayerWTP/Tprovidesareliabletransaction-orientedservicesuitableforwebbrowsingWTP/Dprovidesadatagramservicelightweight:implementablein<=10Kb(lowmemory/computationalneeds)7/30/202347成大資訊鄭憲宗WTP/Dfeatures

(WDPinWAPv1.2)WTP/D(Datagram)providesaconnection-less,unreliabledatagramserviceWTP/DisreplacedbyUDPwhenusedoveranIPnetworklayer.usestheServicePrimitiveT-UnitData.req.ind7/30/202348成大資訊鄭憲宗WAPv1.2WirelessBearers: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)OtherServicesandApplications7/30/202349成大資訊鄭憲宗WTP/Tfeatures

(WTPinWAPv1.2)

WTP/T(Transaction)providesreliabledatatransferbasedonrequest/replyparadigmnoexplicitconnectionsetuporteardowndatacarriedinfirstpacketofprotocolexchangeseekstoreduce3-wayhandshakeoninitialrequest7/30/202350成大資訊鄭憲宗WTP/Tfeatures(cont.)

supportsretransmissionoflostpacketsselective-retransmissionsegmentation/re-assemblyportnumberaddressing(specifictoWTP/T)flowcontrolmessageoriented(notstream)supportsanAbortfunctionforoutstandingrequests7/30/202351成大資訊鄭憲宗WirelessSessionProtocol

WSP/BprovidesupperlayerswithsessionservicesandmanagementWSP/BProvidessemanticsandmechanismsbasedonHTTP1.1WSPprovidesmeansto:establishareliablesessionfromclienttoserveragreeoncommonlevelofprotocolfunctionalitybycapabilitynegotiationcompactencodingsuspendandresume7/30/202352成大資訊鄭憲宗WSPfeaturesHTTP1.1functionalityExchangeofclientandserversessionheadersInterruptmechanismfortransactionsinprocessContentPushfromservertoclientNegotiationformultiple,simultaneousasynchronoustransactions7/30/202353成大資訊鄭憲宗WTLSRecordProtocol

4recordprotocolclients:ThehandshakeprotocolThechangecipherspecprotocolThealertprotocolTheapplicationdataprotocolWTLSconnectionstate:theoperatingenvironmentforrecordprotocolcompression/encryptionalgorithmMACalgorithm--keys7/30/202354成大資訊鄭憲宗RecordProtocolUsage

HandshakeprotocolNegotiatesecureattributesofasecuresessionauthentication,securityparametersettingsChangecipherspecprotocolSignaltransitionsincipheringstrategiessentbeforeverifyingfinishedmessageAlertprotocolconveytheseverityofthemessageandadescriptionofthealert7/30/202355成大資訊鄭憲宗WirelessApplicationEnvironment

(WAE)

7/30/202356成大資訊鄭憲宗WAEComponentsArchitecture–Applicationmodel–Browser,Gateway,ContentServerWML(WirelessMarkupLanguage)–DisplaylanguageWMLScript–ScriptinglanguageContentFormats–Dataexchange7/30/202357成大資訊鄭憲宗WAEIn-DeviceArchitecture7/30/202358成大資訊鄭憲宗WML

Tag-basedbrowsinglanguage:Screenmanagement(text,images)Datainput(text,selectionlists,etc.)Hyperlinks&navigationsupportSyntax:W3CXML(SGMLderivative)InheritstechnologyfromHDMLandHTML7/30/202359成大資訊鄭憲宗WML(cont.)

CardmetaphorUserinteractionsaresplitintocardsNavigationoccursbetweencardsStatemanagementandvariablesReducenetworktrafficResultsinbettercachingExplicitinter-cardnavigationmodelHyperlinksUIEventhandlingHistory7/30/202360成大資訊鄭憲宗WMLExample

7/30/202361成大資訊鄭憲宗WMLScript

Scriptinglanguage:Procedurallogic,loops,conditionals,etc.Optimizedforsmall-memory,small-cpudevicesDerivedfromJavaScript™IntegratedwithWMLPowerfulextensionmechanismReducesoverallnetworktraffic7/30/202362成大資訊鄭憲宗WMLScript(cont.)

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