1. School of Computer Science, Guangzhou University, Guangzhou, China
2. School of Information Science and Technology, Institute of Mobile Communications, Southwest Jiaotong University, Chengdu, China
3. School of Electronics, Electrical Engineering and Computer Science, Queen’s University Belfast, Belfast, U.K
4. School of Electronic Engineering and Computer Science, Queen Mary University of London, London, U.K
5. Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece