1. State Key Laboratory of Rail Traffic Control and Safety, Key Laboratory of Railway Industry of Broadband Mobile Information Communications, School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, China
2. State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China
3. School of Information Engineering, Zhengzhou University, Zhengzhou, China
4. Department of Electronic Systems, Faculty of Engineering and Science, Aalborg University, Aalborg, Denmark