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. Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, China
3. School of Computer Science and Engineering, Nanyang Technological University, Jurong West, Singapore
4. Department of Electrical and Computer Engineering, Hong Kong University of Science and Technology, Sai Kung, Hong Kong