1. School of Information and Electrical Engineering, Hebei University of Engineering, Handan, China
2. School of Information and Control Engineering, China University of Mining and Technology, Xuzhou, China
3. Department of Communication Engineering, Beijing Electronics Science and Technology Institute, Beijing, China
4. School of Electronics, Electrical Engineering and Computer Science, Queen’s University Belfast, Belfast, U.K
5. Department of Electrical and Computer Engineering, University of Houston, Houston, TX, USA