1. School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo, China
2. College of Computer Science and Electronic Engineering, Hunan University, Changsha, China
3. School of Information Science and Electrical Engineering, Shandong Jiaotong University, Jinan, China
4. Department of Electronics and Information Engineering Central China Normal University, Wuha, China
5. Department of Engineering, Manchester Metropolitan University, Manchester, U.K.