With the deployment of technologies, Communication Based Train Control (CBTC) system has been widely applied in rail transportation. The bidirectional train-way communication is one of its key technologies. One main application is taking the use of wireless communication of IEEE 802.11.But because of its character of radio and working frequency on ISM band, the interference is unavoidable. Hence, the research of 802.11 interference in CBTC system, and the system performance under interference, is meaningful to analyze the system.In the thesis, firstly, combined with IEEE 802.11, the topology of CBTC system, the path of the data stream, and the characteristic of the wireless channel are expatiated. Whereas the powerful function of module and convenient simulation of wireless channel, the tool of OPNET is chosen. By the analysis of the radio wave transmission and its large scale and small scale path loss in open space, it gets an transmission mode fitted for the radio environment of rail traffic.Secondly, it specifies the several interferences that may effect on the system.
