1. Beijing Key Laboratory of Network System Architecture and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
2. College of Information Science and Electronic Engineering, Zhejiang Key Laboratory of Information Processing Communication and Networking, Zhejiang University, Zhejiang, China
3. Faculty of Applied Science, School of Engineering, The University of British Columbia, Kelowna, Canada
4. Beijing Laboratory of Advanced Information Networks, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China