1. College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, 47854 Nanjing, Jiangsu, China, (e-mail: yalewang@nuaa.edu.cn)
2. College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China, (e-mail: chwang@nuaa.edu.cn)
3. EEECS, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom of Great Britain and Northern Ireland, BT3 9DT (e-mail: cgu01@qub.ac.uk)
4. College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China, (e-mail: yijun.cui@nuaa.edu.cn)
5. ECIT, Queens University Belfast, Belfast, Antrim, United Kingdom of Great Britain and Northern Ireland, BT39DT (e-mail: m.oneill@ecit.qub.ac.uk)
6. College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China, 211106 (e-mail: liuweiqiang@nuaa.edu.cn)