Application Of IEEE 802.11n Protocol In Communications-Based Train Control System

In September 1999, IEEE declares CBTC(Communications Based Train Control) as a continuous, automatic train control system utilizing high-resolution, train location determination independent of track circuits; continuous, high capacity, bi-directional train-to-wayside data communications; and train borne and wayside processors capable of implementing vital functions. This system ensures fast and secure trains’operations and is becoming mainstream trend to modern train control system. With fast development on wireless communication technology, wireless LAN protocol IEEE 802.11b has been applied into the use of train control system. This system not only satisfies the need of train communication, but also simplifies construction difficulties、system maintenance and update in future.We have put forward the scheme that is the implementation of IEEE802.11n protocol in CBTC system in this paper. We have carefully studied the possible problems and the proper schemes during the process of the implementation.First, in chapter 2 and chapter 3 some key technologies in PHY and MAC layer have been studied, which bring better ability of resisting noises and high data speed. It seems this implementation is quite promising.Then, possible problems have been carefully studied when put the IEEE802.11n protocol into practice. On the basis of former deep analysis, we get the network infrastructure and wireless devices needed, such as antenna etc. According to the train’s fast running speed, the communication based train control system has stiff requirements to system delay and data rate speed, so a quick roaming scheme is designed to satisfy the system needs. From the simulation results about association delay and data loss rate by Matlab, the roaming scheme that the paper has proposed can well improve system performance on association delay and data loss rate. The simulation results also set a good reference to future use of IEEE 802.11n protocol and current application of IEEE 802.11b/g protocol.In the end of this paper, main study contents and future prospects in this field to be researched in the future are summarized.