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兰州交通大学毕业设计（论文）I摘要CBTC（CommunicationBasedTrainControl，基于通信的列车控制）系统利用连续、大容量的车地双向可靠数据通信来实现列车控制信息、列车状态信息的无线传输，是先进的列车自动控制系统。通过CBTC系统可以减小行车间隔，安全、高效、可靠地实现全方位、多功能的列车控制，而且即使在发生故障的情况下也可以采用备用模式安全运行，从而保证了行车安全，提高了铁路线路的利用率。DCS（DigitalCommunicationSystem，数据通信系统）子系统实现车地之间双向、连续、高速、安全的信息交互，承载了直接关系到行车安全的重要数据信息，是CBTC系统的核心。论文从CBTC系统和DCS系统的发展历程及系统构成入手，对DCS系统的轨旁有线骨干网络和车地无线通信网络两大模块进行了详细的阐述，对网络的组网方式、协议配置、功能以及设备的性能做了详细的描述。提出以采用TCP/IP协议的以太网为轨旁骨干网络、以WLAN（WirelessLAN，无线局域网）为车地无线通信网络的数据传输系统作为DCS子系统的解决方案。论文对DCS系统可能受到的网络安全威胁从两方面进行了阐述，根据DCS系统的组网方式和协议结构，提出具有针对性的解决方案，并对与网络安全相关的频率规划和冗余设计做了简单说明。关键词：DCS，轨旁骨干网络，车地通信网络，WLAN，安全传输，接入认证兰州交通大学毕业设计（论文）IIAbstractTheCBTC(CommunicationBasedTrainControl)systemisanadvancedtrainautomaticcontrolsystemwhichmakesuseofbi-directional,big-capacitydigitalcommunicationbetweenwaysideandtrain,totransfertheinformationofthestatusofthetrain,aswellasthecontrollinginformation.ByusingCBTCsystem,wecanreducetheintervalbetweentrainsachievinghighround,multi-traincontrolsafely,efficientandreliably.Eveninthecaseoffailure,thestandbymodemaybeusedforsafeoperation.Thus,weensuretrafficsafetysothatimprovingtheutilizationoftherailwayline.ThecorepartofCBTCisDCS(DigitalCommunicationSystem)subsystem,whichachievetwo-way,continuous,high-speed,secureinformationexchangebetweenvehiclesanddestinations,carringimportantdatainformationrelavanttotrafficsafetydirectly.StartingfromdevelopmentprocessandsystemconfigurationofCBTCsystemandDCSsystem,IelaboratedtwomodulesincludingthewiredsidingsbackbonenetworkofDCSsystemandthewirelesscommunicationnetworkbetweentrainsanddestinations,thecompositionofthenetwork,configurationrequirements,function,andperformanceoftheequipment.Weproposeadatatransmissionsystem,asasolutionofDCSsubsystem,adoptingEthernetbasedonTCP/IPprotocolasterrestrialbackbonenetworkandWLAN(WirelessLocalAreaNet)asawirelesscommunicationnetwork.Inthearticle,networksecuritythreatsthatDCSsystemmaysufferaredescribedintwoways.AccordingtonetworkingandprotocolstructureofDCSsystems,weproposetargetedsolutions,andgiveabrifintroductionforfrequencyplanningandredundantdesignrelavanttonetworksecurity.KEYWORDS:DCS,Tracksidebackbonenetwork,Trainandterrestrialcommunicationsnetwork,WLAN,Securetransmission,Accessauthentication兰州交通大学毕业设计（论文）III目录1.绪论.............................................................................................................................11.1选题背景及意义.................................................................................................11.2基于通信的列车控制系统（CBTC）...............................................................11.2.1CBTC系统的出现....................................................................................11.2.2CBTC系统的结构....................................................................................21.3数据传输子系统（DCS）.................................................................................41.3.1DCS子系统的组成..................................................................................41.3.2DCS子系统的发展..................................................................................61.4论文主要内容及章节安排.................................................................................62.DCS系统网络............................................................................................................82.1轨旁骨干网络.....................................................................................................82.2轨旁数据接入网络.............................................................................................92.3车载数据通信网络...........................................................................................102.3.1车载网络系统的组成............................................................................102.3.2IEEE802.11标准....................................................................................112.3.3无线设备................................................................................................112.3.4无线覆盖................................................................................................122.3.5越区切换................................................................................................122.3.6无线网络冗余........................................................................................122.3.7无线抗干扰............................................................................................132.4车地双向通信网络...........................................................................................142.5DCS子系统对WLAN的要求.........................................................................162.6DCS子系统的性能...........................................................................................172.6.1网络的整体性能....................................................................................172.6.2系统的基本要求....................................................................................183.DCS子系统的安全传输设计..................................................................................203.1DCS子系统面临的安全威胁...........................................................................203.1.1轨旁骨干网络受到的安全威胁..