1. State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, P.R. China
2. School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, P.R. China
3. Beijing Engineering Research Center of High-Speed Railway Broadband Mobile Communications, Beijing Jiaotong University, Beijing, P.R. China
4. Beijing Key Laboratory of Intelligent Traffic Data Safety and Privacy Protection Technology, Beijing Jiaotong University, Beijing, P.R. China