1. Engineering Research Center of Network Management Technology for High Speed Railway of Ministry of Education, School of Computer and Information Technology, the Collaborative Innovation Center of Railway Traffic Safety, and the National Engineering Research Center of Advanced Network Technologies, Beijing Jiaotong University, Beijing, China
2. Beijing National Research Center for Information Science and Technology and the Department of Electronic Engineering, Tsinghua University, Beijing, China
3. School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, Australia
4. Department of Electrical and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China