Improvement And Analysis On GSM-R Circuit Switch Data Transmission Under High Speed Environment

China train control system-level 3 is widely used in the high-speed railways across China, and data transmission between onboard and trackside in CTCS-3 system is provided by circuit switch data services of GSM-R network. Compared to low-speed or static conditions, data transmission under high-speed conditions is suffered from problems of frequently short interruptions, data error rate increasing and transmission abort issues due to some adverse effects, such as Doppler shift, fast changing multi-path effect, frequent handoff and other factors. It will affect the security and reliability of the train control system.According to the current situation of China, the paper deeply researches the characteristics of data transmission under high speed conditions, and proposes improvement strategy to enhance the reliability of data transmission. First of all, GSM-R circuit data transmission characteristics and the factors which affect data transmission under high-speed conditions are discussed. Then the test data collected from Zhengzhou-xi'an dedicated passenger line is counted to analyze the affection of circuit switch data transition from high speed. And the test results indicate that data transmission error rate of downlink and uplink will both be increased along with the increasing train speed, so the reliability of data transmission will be reduced. This paper proposes two improvement strategies in order to overcome the impact from high-speed, also to improve the reliability of data transmission. On one hand, MIMO technology is introduced to the railway area in order to improve the performance of the wireless channel, and a link level simulation model based on MIMO system under high speed railway is established, also the applicability and improved quality are analyzed according to the current network. On the other hand, the paper mainly focused on how to improve the current structure of CTCS-3 system. According to this issue, a solution of cross-connecting the GSM-R antennas of the CTCS-3 system in the different cabin, also applying dual redundant data transmission is proposed. Then, the advantages and disadvantages of the improved scheme are analyzed combining with the communication failure happened in Zhengzhou-xi'an dedicated passenger line.