1. School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China
2. China United Network Communications Corporation, Beijing, China
3. Shaanxi Key Laboratory of Information Communication Network and Security, Xi’an University of Posts and Telecommunications, Xi’an, China
4. School of Communications and Electronics Engineering, East China Normal University, Shanghai, China
5. School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
6. Information Systems Technology and Design Pillar, Singapore University of Technology and Design, Tampines, Singapore