1. Key Laboratory of Information and Communication Systems, Ministry of Information Industry, and Laboratory of Optoelectronic Measurement Technology and Instrument, Ministry of Education, Beijing Information Science and Technology University, Beijing, China
2. Key Laboratory of Modern Measurement and Control Technology, Ministry of Education, and School of Information and Communication Engineering, Beijing Information Science and Technology University, Beijing, China
3. College of Telecommunications and Information Engineerning, Nanjing University of Posts and Telecommunications, Nanjing, China
4. Department of Engineering, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, U.K.
5. Faculty of Electrical Engineering and Information Technology, RWTH Aachen University, Aachen, Germany