校园无线网路技术与应用发展-英文版

校園無線網路技術與應用發展Sheng-TzongCheng

鄭憲宗stcheng@.tw.tw10/8/20231Outline無線區域網路─IEEE802.11無線應用通訊協定─WAP10/8/20232成大資訊鄭憲宗無線區域網路通訊協定WirelessLocalAreaNetwork(IEEE802.11)10/8/20233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.10/8/20234成大資訊鄭憲宗IEEE802.11規範IEEEProject802Charter:Local&MetropolitanAreaNetwork1Mbpsto100Mbpsandhigher2lowerlayersof7LayerOSIReferenceModelIEEE802.11WorkingGroupscope:Wirelessconnectivityforfixed,portableandmovingstationswithinalimitedareaAppeartohigherlayer(LLC)thesameasexisting802standardsApplicationLayerNetworkLayerMACPhysicalLayer...LLCIEEE802.11DataLinkLayer10/8/20235成大資訊鄭憲宗1997/6/26通過成為IEEE802系列標準IEEE802.11架構MediaAccessControlLogicalLinkControlInfraredPhysicalLayerFHSSPhysicalLayerDSSSPhysicalLayer10/8/20236成大資訊鄭憲宗AdHoc網路OneBasicServiceSetDirectedConnectionLimitedCoverageArea10/8/20237成大資訊鄭憲宗APBSSInfrastructure網路APBasicServiceSetExistingWiredLANDistributionSystemOtherLANsExtendServiceSet10/8/20238成大資訊鄭憲宗Infrastructure網路(cont.)AccessPointandMobileStationDistributedSystemInterconnectMultipleCellsviaAccessPointstoformasinglenetworkExtendsWirelessCoverageAreaMultipleBasicServiceSetsconnectedtogetherformanExtendedServiceSetAllowMobileStationtoaccessfixedresourceSupportRoamingforMobileStationsviaAccessPointPointCoordinationFunction,PowerManagement,TimeSynchronizationsupportthroughAccessPoint10/8/20239成大資訊鄭憲宗IEEE802.11ServicesProvidesserviceswiththefollowingfunctionality:roamingwithinaESS,multipledataratesinBSSsandPowerManagement.TheMACprotocolisCarrierSenseMultipleAccesswithCollisionAvoidance(CSMA/CA)MACservicesAssociationserviceAuthenticationserviceDistributionserviceIntegrationserviceDeauthentication/Deassociationservice10/8/202310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。10/8/202311成大資訊鄭憲宗直接序列展頻（DSSS）10/8/202312成大資訊鄭憲宗跳頻展頻（FHSS）10/8/202313成大資訊鄭憲宗IEEE802.11TGaTheTGaisworkingonthehighdata-rateextensioninthe5GHzband,project802.11a,wasabletoproduceanewdraftstandardthathasthesupportofatleast80%ofthemembers.TGaislookingatacandidateforworldwidestandardization!10/8/202314成大資訊鄭憲宗IEEE802.11TGa(cont.)ThespecificationsofthePhysicalLayerencompassdataratesfrom6Mbit/supto54Mbit/s,with20MHzspacingbetweenadjacentchannels.Allimplementationsarerequiredtosupport6,12and24Mbit/s.Optionalextensionsarefor9,18,36,48and54Mbit/s.Themulti-ratemechanismoftheMACprotocolensuresthatalldevicescommunicatewitheachotheratthebestdatarateinthepresentchannel.10/8/202315成大資訊鄭憲宗IEEE802.11TGbTheTGbisworkingontheextensionofthe1and2Mbit/sdataratesinthe2.45GHzbandwith5.5and11Mbit/shasreachedatechnicalcompromisesolutiontoimprovetheco-existenceandinteroperabilitycharacteristicsbetweenoptions.Themulti-ratemechanismwarrantsthatthe11Mbit/soperationcanswitchbackto5.5Mbit/s.Stationsthatareevenfurthercouldswitchbacktothe2and1Mbit/scapabilitiesoftheDSSSmodulation.10/8/202316成大資訊鄭憲宗CSMA/CD(LAN)Senddataifthemediumissensed“idle”Ifcollideswithotherhost(s), thenbackoffforarandomnumberoftimesRe-senddatalater10/8/202317成大資訊鄭憲宗HiddenTerminalProblemBACdatadata10/8/202318成大資訊鄭憲宗SolutiontoHTPBACRequestGrant10/8/202319成大資訊鄭憲宗DetectionofCollisionBACRequestRequest10/8/202320成大資訊鄭憲宗BACRequestAisGrantAisGrantDCollisionAvoidance10/8/202321成大資訊鄭憲宗RTS/CTS/data/ACKandNAVsetting10/8/202322成大資訊鄭憲宗SomeIFSrelationshipsandbasicaccessmethod10/8/202323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10/8/202324成大資訊鄭憲宗AnexampleofexponentialincreaseofCW10/8/202325成大資訊鄭憲宗Backoffprocedure10/8/202326成大資訊鄭憲宗Transmissionofamulti-fragmentMPDUusingSIFS10/8/202327成大資訊鄭憲宗RTS/CTSwithfragmentedMSDU10/8/202328成大資訊鄭憲宗RTS/CTSwithtransmitterpriorityandmissedacknowledgment10/8/202329成大資訊鄭憲宗Directdata/ACKMPDU10/8/202330成大資訊鄭憲宗無線區域網路軟體技術架構WLANPlatformEmbeddedControlSoftwareWLANManagementUtilityNetworkApplicationsDSSSFHSSMediaAccessControlNetworkDriver(NDIS)SocketInterfaceMobileIPSNMPAgentSecurityDistributedServiceE-MailFileTransferRemoteAccessMobileDataDECTU-NIIorISMbandETSI10/8/202331成大資訊鄭憲宗無線應用通訊協定WirelessApplicationProtocol(WAP)10/8/202332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一10/8/202333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)10/8/202334成大資訊鄭憲宗全球無線通訊用戶成長10/8/202335成大資訊鄭憲宗預估未來WAP手機的佔有率10/8/202336成大資訊鄭憲宗10/8/202337成大資訊鄭憲宗10/8/202338成大資訊鄭憲宗手持型元件之延革10/8/202339成大資訊鄭憲宗10/8/202340成大資訊鄭憲宗bringtheinternetcontentandadvancedservicesto後PC時代之userscreateaglobalwirelessprotocoltoworkacrossdifferingwirelessnetworktechnologies

enableapplicationstoscaleacrossavarietyoftransportoptionsanddevicetypesWhat’sWAPfor?10/8/202341成大資訊鄭憲宗WhatisdefinedinWAP?Micro-BrowserScriptingtoenhanceMScapabilitiesWTA/WTAIfortelephonefunctionality(e.g.callchains)ContentFormatsbusinesscard(vCard)calendarevent(vCalendar)LayeredTelecommunicationStack10/8/202342成大資訊鄭憲宗Comparison10/8/202343成大資訊鄭憲宗10/8/202344成大資訊鄭憲宗GoalsforWTP(WAPv1.1)acommoninterfacetophysicaltransportmechanismsprovideaport-basedabstractinterfacetoupperlayerprotocolsallowapplicationsdesignedindependentfromspecifictransportsextensibletoavarietyofdigitalwirelessnetworksandfuturetransportoptions10/8/202345成大資訊鄭憲宗GoalsforWTP(cont.)supportsconnection-oriented,transaction,anddatagrammodesoptimizefornarrowtomediumbandwidthchannelstobecapableofimplementationinalowmemoryfootprint,suitableforstandardorlow-IQhandsets10/8/202346成大資訊鄭憲宗RequirementsforWTPWTP/Cprovidesareliableconnection-orientedservicetotheupperlayerWTP/Tprovidesareliabletransaction-orientedservicesuitableforwebbrowsingWTP/Dprovidesadatagramservicelightweight:implementablein<=10Kb(lowmemory/computationalneeds)10/8/202347成大資訊鄭憲宗WTP/Dfeatures

(WDPinWAPv1.2)WTP/D(Datagram)providesaconnection-less,unreliabledatagramserviceWTP/DisreplacedbyUDPwhenusedoveranIPnetworklayer.usestheServicePrimitiveT-UnitData.req.ind10/8/202348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)OtherServicesandApplications10/8/202349成大資訊鄭憲宗WTP/Tfeatures

(WTPinWAPv1.2)

WTP/T(Transaction)providesreliabledatatransferbasedonrequest/replyparadigmnoexplicitconnectionsetuporteardowndatacarriedinfirstpacketofprotocolexchangeseekstoreduce3-wayhandshakeoninitialrequest10/8/202350成大資訊鄭憲宗WTP/Tfeatures(cont.)

supportsretransmissionoflostpacketsselective-retransmissionsegmentation/re-assemblyportnumberaddressing(specifictoWTP/T)flowcontrolmessageoriented(notstream)supportsanAbortfunctionforoutstandingrequests10/8/202351成大資訊鄭憲宗WirelessSessionProtocol

WSP/BprovidesupperlayerswithsessionservicesandmanagementWSP/BProvidessemanticsandmechanismsbasedonHTTP1.1WSPprovidesmeansto:establishareliablesessionfromclienttoserveragreeoncommonlevelofprotocolfunctionalitybycapabilitynegotiationcompactencodingsuspendandresume10/8/202352成大資訊鄭憲宗WSPfeaturesHTTP1.1functionalityExchangeofclientandserversessionheadersInterruptmechanismfortransactionsinprocessContentPushfromservertoclientNegotiationformultiple,simultaneousasynchronoustransactions10/8/202353成大資訊鄭憲宗WTLSRecordProtocol

4recordprotocolclients:ThehandshakeprotocolThechangecipherspecprotocolThealertprotocolTheapplicationdataprotocolWTLSconnectionstate:theoperatingenvironmentforrecordprotocolcompression/encryptionalgorithmMACalgorithm--keys10/8/202354成大資訊鄭憲宗RecordProtocolUsage

HandshakeprotocolNegotiatesecureattributesofasecuresessionauthentication,securityparametersettingsChangecipherspecprotocolSignaltransitionsincipheringstrategiessentbeforeverifyingfinishedmessageAlertprotocolconveytheseverityofthemessageandadescriptionofthealert10/8/202355成大資訊鄭憲宗WirelessApplicationEnvironment

(WAE)

AnInternet(WWW)programmingmodel

Vendor-controlledMMIInitialfocusonphonesSlowbearersSmallmemoryLimitedCPUSmallscreenLimitedinputmodel10/8/202356成大資訊鄭憲宗WAEComponents

Architecture–Applicationmodel–Browser,Gateway,ContentServerWML(WirelessMarkupLanguage)–Displaylanguage

WMLScript–ScriptinglanguageContentFormats–Dataexchange10/8/202357成大資訊鄭憲宗WAEIn-DeviceArchitecture10/8/202358成大資訊鄭憲宗WML

Tag-basedbrowsinglanguage:Screenmanagement(text,images)Datainput(text,selectionlists,etc.)Hyperlinks&navigationsupportSyntax:W3CXML(SGMLderivative)InheritstechnologyfromHDMLandHTML10/8/202359成大資訊鄭憲宗WML(cont.)

CardmetaphorUserinteractionsaresplitintocardsNavigationoccursbetweencardsStatemanagementandvariablesReducenetworktrafficResultsinbettercachingExplicitinter-cardnavigationmodelHyperlinksUIEventhandlingHistory10/8/202360成大資訊鄭憲宗WMLExample

<?xml

version="1.0"?><!DOCTYPEwmlPUBLIC"-//WAPFORUM//DTDWML1.1//EN""/DTD/wml_1.1.xml"><wml> <card

id="main"> <do

type="accept"> <go

href="#ecard"/> </do> <p>Welcome!</p> </card> <card

id="ecard"> <do

type="accept"> <go

href="#ecardN=$(N);S=$(S)"/> </do> <p> Entername:<inputname="N"/> speed: <selectname="S"> <option

value="0">Fast</option> <option

value="1">Slow</option> </select> </p> </card></wml>10/8/202361成大資訊鄭憲宗WMLScript

Scriptinglanguage:Procedurallogic,loops,conditionals,etc.Optimizedforsmall-memory,small-cpudevicesDerivedfromJavaScript™IntegratedwithWMLPowerfulextensionmechanismReducesoveral