1. School of Computer and Information Technology, Engineering Research Center of Network Management Technology for High Speed Railway of Ministry of Education, Beijing Jiaotong University, Beijing, China
2. Department of Electrical and Computer Engineering, University of Victoria, Victoria, Canada
3. InfoLab21, School of Computing and Communications, Lancaster University, Lancaster, U.K.
4. Beijing National Research Center for Information Science and Technology, China
5. Department of Electrical and Computer Engineering, Hong Kong University of Science and Technology (HKUST), Hong Kong