1. Engineering Research Center of Network Management Technology for High Speed Railway of Ministry of Education, School of Computer and Information Technology, Beijing Jiaotong University, Beijing, China
2. State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China
3. Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, China
4. Department of Electrical and Computer Engineering, The Hong Kong University of Science and Technology (HKUST), Hong Kong