1. School of Electronic Information, Beijing Information Technology College, Beijing, China
2. School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China
3. School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin, China
4. School of Electrical and Electronic Engineering, Nanyang Technological University, Jurong West, Singapore
5. PetroChina Research Institute of Petroleum Exploration and Development, Beijing, China
6. Department of Communication Engineering, Communication University of China, Beijing, China