CBTC列车安全定位中通信中断时间的研究

通信中断的存在会对目前城市轨道交通的CBTC列车安全定位产生影响,进而影响列车安全间隔距离。CBTC车地通信系统大多采用无线局域网技术。越区切换中断是导致通信中断的主要原因,根据IEEE 802.11协议的越区切换流程,本文推导出越区切换中断时间与列车速度的关系表达式,在此基础上根据安全定位的实现方法和移动闭塞系统中列车安全间隔距离的计算方法,推导出通信中断时间与影响安全定位的因素之一——估计的运行距离及列车运行安全间隔之间的关系表达式。建立两列列车追踪运行模型,仿真不同通信中断时间下两列车的追踪间隔距离。采用此关系表达式进行理论计算的结果与仿真结果验证了通信中断时间与估计的运行距离及列车运行安全间隔的关系表达式是合理的。

Research on Time of Communication Interruption in Safe Positioning of CBTC Train

Interruption of communication will influene safety of CBTC train positioning,thus resulting in affecting the safe headway.The wireless local area network(WLAN) technology is adopted in most CBTC train-wayside communication systems.Handover is the main factor which leads to interruption of communication.According to the procedure of handover specified in IEEE 802.11,the relational expression between the time of handover interruption and the train speed was deduced.Then relational expression between the time of communication interruption and the estimated train running distance & safe headway was derived.The two consecutive trains tracing model was established to simulate the headways between the two consecutive trains corresponding to different periods of time of communication interruption.Calculation and simulation results verify the rationality of the relational expression between the time of communication interruption and the estimated train running distance & safe headway.