1. School of Information and Communication Engineering, University of Electronic Science and Technology of China, China and Department of Computer Science, St. Francis Xavier University, Nova Scotia, Canada
2. School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
3. School of Computer Science, Fudan University, Shanghai, China
4. School of Information and Communication Engineering, University of Electronic Science and Technology of China, China and Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada