1. National Mobile Communications Research Laboratory, Southeast University, Nanjing, China
2. School of Computer Science and Communication Engineering and the Jiangsu Key Laboratory of Security Technology for Industrial Cyberspace, Jiangsu University, Zhenjiang, China
3. State Key Laboratory of Mobile Network and Mobile Multimedia Technology, Shenzhen, China
4. Centre for Telecommunications Studies, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil