1. Jiangsu Key Laboratory of Wireless Communications, and the Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks, Ministry of Education, Nanjing University of Posts and Telecommunications, Nanjing, China
2. Department of Electrical and Electronic Engineering, University of Warwick, Coventry, U.K.
3. School of Electronics and Communication Engineering, Sun Yat-sen University (Shenzhen), Shenzhen, China
4. Information Systems Technology and Design Pillar, Singapore University of Technology and Design, Tampines, Singapore