1. Research Center for Convergence Networks and Ubiquitous Services, University of Science and Technology Beijing (USTB), Beijing 100083, China
2. State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing China
3. Offshore Oil Engineering Co., Ltd Engineering Company, Tianjin China
4. Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang China
5. Department of Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne, UK