Research Of Radio Interference Technology For Urban Rail Transit CBTC System

CBTC (Communications-Based Train Control) system has features of real-time bidirectional communication and so on, which is ideal for moving block system, CBTC system is the developing trend for urban rail transit control system. Currently, CBTC system uses ISM (Industrial Scientific Medical) band for wireless communication, it is vulnerable to be interfered by radio waves in the open electromagnetic environment. Therefore, there is important significance for the research of CBTC system radio interference technology, in order to insure safe and reliable operation of CBTC system.First of all, the development situation of CBTC system radio interference technology at home and abroad is summarized in this paper. Based on the analysis of the structure of urban rail transit, the feature of fixed block system, the feature of quasi-moving block system and the the feature of moving block system which is based on communication are compared and analyzed, then the structure of the CBTC system and the propagation modes which are based on free-space, the crack waveguide and the leaky coaxial cable are described in detail, radio wave propagation mechanism, path loss, wireless interference includes the interference of CBTC system devices, the interference of Bluetooth and the interference of WLAN for CBTC system are also explained in this paper.. Next, the solutions of CBTC system immunity performance test such as interference threshold test and space split test are proposed and designed, then the interference threshold results of co-channel, the first adjacent channel, the second adjacent channel, the third adjacent channel, free-space transmission mode, crack waveguide transmission mode and leaky coaxial cable transmission mode are obtained and analyzed. Finally, according to the NS2network simulation software which is based on the Linux operating system, single node fixed model, multi-node fixed model, multi-mobile node model are designed and achieved by using TCL language, the parameters about CBTC system communication status such as loss rate, total delay, throughput are shown directly by using AWK data analysis tool and Gnuplot drawing tool, then largest user interference tolerance in CBTC system under the same frequency interference are calculated at the end.