I. Introduction
The train operation dispatching command system (TDCS) has experienced rapid development in recent years by the aid of information technology and it has covered China Railway Corporation, 18 railway bureaus and nearly 8000 stations and realized transparent command, real-time adjustment and centralized control of train operation [1]. The train operation density is gradually increasing and tracking intervals gradually decreasing along with the train speed-raise for multiple times. As services and functions of the TDCS are constantly extended and strengthened, dispatching command is increasingly depending on TDCS and it becomes difficult to fulfill train dispatch without the system. Consequently, it requires a higher level of stability, reliability and security of the TDCS [2] [3].