1. School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing, China
2. Department of Computer Science and Engineering, University of Nevada, Reno, NV, USA
3. 4th System Department, North China Institute of Computing Technology, Beijing, China
4. Department of Electrical and Computer Engineering, University of Houston, Houston, TX, USA
5. School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia