Research On The Digital Communication System Of The CBTC System For Metro Railway Transportation

The CBTC (Communication-Based Train Control) system is an advanced train control system which makes use of bi-directional, big-capacity digital communication between wayside and train, to transfer the information of the status of the train, as well as the controlling information. By using CBTC system, we can reduce the interval between trains, carry out more function, maximize the utilization of the rail transit infrastructure, and supply more safety. The channel, in which the data is transfered in the CBTC system, is called DCS (Digital Communication System). DCS is the core part of CBTC. At the begining, the paper introduced the onground backbone network and the wireless digital transfer system in the DCS, disscussed the function and characteristics of these two networks. Based on the background of metro railway transportation, the paper brought out a blue print of DCS, which used wired ethernet and WLAN(Wireless Local Area Net). The paper also took some methodologies to test the WLAN equipment.The paper then analysed the potential harm, which may be done by network intrusion, to the DCS. Some resolvents against the attack were introduced in the paper, especially the IPSec (Internet Protocol Security). The designing and implementation of a Security Device, which was based on real-time OS VxWorks and IPSec, was described in the paper. The SD can protect the DCS from network attacks.At last ,the paper established a model for DCS, and carried out a simulation.