1. School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, China
2. Department of Computer Science, Memorial University of Newfoundland, St. John's, NL, Canada
3. School of Cyberspace Science and Technology, Beijing Institute of Technology, Beijing, China
4. Department of Electrical and Computer Engineering, University of Windsor, Windsor, Canada
5. Future Network of Intelligence Institute (FNii) and the School of Science and Engineering, the Chinese University of Hong Kong, Shenzhen, China