1. College of Microelectronics and Communication Engineering, Chongqing University, Chongqing, China
2. School of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing, China
3. Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services, University of Science and Technology Beijing, Beijing, China
4. Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada