A Study of Real-Time Data Transmission Model of Train-to-Ground Control in High-Speed Railways

CBTC (Communication Based Train Control) will be based on mobile communication, which the key problem is how to support reliability of control data transmission to improve track utilization and enhance train safety. This paper proposed a kind of real-time transmission model for high speed train end-to-end control data operation, which based on circuit switched data service by traditional wireless network access to transmit simultaneous instructions between the train operation control system and locomotive. In order to support this end-to-end real-time data application, we have studied a circuit domain latency model and improved a Simple Tunnel Protocol technology to accelerate data service which is easy to be implemented in the network. We have analyzed the performance under different service pressure by using MMPP (Markov Modulation Poisson Process) to describe service traffic pattern and employed a priority scheduling algorithm to estimate approximate service latency. The system simulation showed that data transmission latency should be reduced in busy time by the way of service priority scheduling. Although it might introduce extra traffic expenses and require reservation certain protection circuit, the average standby time probability could be cut down significantly.