1. School of Information Science and Technology, Southwest Jiaotong University, Chengdu, China
2. Institute of Intelligent Systems, National Yang Ming Chiao Tung University, Tainan City, Taiwan
3. Center for Intelligent Networking and Communications (CINC), University of Electronic Science and Technology of China, Chengdu, China
4. School of Computer Science and Engineering, Nanyang Technological University, Jurong West, Singapore
5. Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, Canada