1&2.WLAN基础和主要协议

MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.无线WLAN概述和主要协议MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.内容安排•SpreadSpectrum基础•无线局域网•其它无线网络标准•IEEE802.11MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.SpreadSpectrum基础MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.•信号能量的单位：Watts/Decibels30dBm=1000mw(1Watt)27dBm=500mw24dBm=250mw20dBm=100mw(2.4Ghz无线局域网标准)18dBm=63mw17dBm=50mw14dBm=25mw10dBm=10mw7dBm=5mw0dBm=1mw-80dBm=.00000001mw(无线局域网接收门限)无线能量MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.无线传输带宽•传输和处理数据的能力带宽的单位：kHz/MHz在通常的调制方式中：1Hz=1bit带宽越大，传输数据的能力越强，速度越快理想状态的信号传输的数据可用带宽全部带宽MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.无线电通讯•窄波段通讯(NarrowBand)传送方和接收方在单一频点上工作要求终端用户许可证•频谱传播技术(SpreadSpectrum)当今最广泛使用的无线网络技术源于军用技术的宽波段通讯方式两种频谱传播技术扩谱跳频技术直序扩频技术•红外线(Infrared)高频通讯很少有商业化无线网络的应用需要直视环境,通讯距离有限MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.频谱传播技术的历史•诞生于1942年，发明人HedyLamar和GeorgeAntheil•美国国家专利号2,292,387•第一个军事应用案例：1962年古巴导弹事件MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.频谱传播技术•FCC1985年认可的三个商用通讯频率902MHz,2.4GHz,5.15GHz通讯频率段902MHz在美洲和澳洲开放使用2.4GHz在全球范围内开放使用•无需客户端许可证，所有用户工作于同一频段双向的无线通讯收发双方使用同一通讯频率•频率资源共享，但资源日益缺乏各国指定相关的无线电管理美国FCC通信委员会ITU国际电信联盟MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.频谱传播技术基础•频谱传播技术的特性传播信号的带宽远远大于数据信号的带宽能量散布在一个很宽的频率上自动协调信号带宽和信号噪声比数据信号和扩频模式整合•包含两部分信号无线载波信号数据信号两种信号整合的方式称为信号的调制MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.国际无线电无线频谱管理体系•InernationalTelecommunicationsUnion•RadiocommunicationSector(ITU-R)••WorldAdministrativeRadioConferences(WARC)•协调各管理区域RegionA:美洲RegionB:西欧RegionC:东欧和北亚RegionD:非洲RegionE:亚洲和澳洲各国政府控制和管理本地无线电频谱MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.2.4G公用频段ChannelFreq(GHz)AmericaEMEAIsraelChinaJapan12.412XXXX22.417XXXX32.422XXXXX42.427XXXXX52.432XXXXX62.437XXXXX72.442XXXXX82.447XXXXX92.452XXXXX102.457XXXX112.462XXXX122.467XX132.472xX142.484xMOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.5GHz公用频段RegulatoryDomainBand(GHz)#ofChannelChannelnumberCenterFreqAmerica/EMEAU-NIILower436,40,44,485180520052205240America/EMEAU-NIIMiddle452,56,60,645260528053005320America/EMEAU-NIINew11100,104,108,112,116,120,124,128,132,136,14055005520554055605580560056205640566056805700America/EMEAU-NIIUpper5.725-5.8254149,153,157,1615745576557855805AmericaISM5.725-5.85011655825MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.无线局域网MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.IEEE802.11标准定义到介质存取控制层采用以态网的架构MAC–电能，安全等TCPIPLLC–802.2FH,DS,IR,CCK(b),OFDM(a)应用层表示层会话层传输层网络层逻辑链路层介质存取控制层物理层网络操作系统(NOS)802.11MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.第二层桥架构网络协议(SPX/IPXTCP/IP)接口(e.g.NDIS)无线链接层无线物理层客户端应用系统网络协议(SPX/IPXTCP/IP)接口(e.g.NDIS)链接层物理层桥功能无线链接层有线链接层无线物理层有线物理层移动设备服务器AccessPoint客户端应用系统IEEE802.11IEEE802.3MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.无线网络的拓扑结构•Ad-HOC(对等结构)•客户端网络存取点•无线网桥•无线中继器•中心点无线局域网MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.Ad-HOC(对等结构)MOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveowners.©Motorola,Inc.2008.客户端网络存取点(胖AP架构)WANMOTOROLAandtheStylizedMLogoareregisteredintheUSPatent&TrademarkOffice.Allotherproductorservicenamesarethepropertyoftheirrespectiveo