1. The School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100084, China
2. The Institute of Science and Technology for Opto-electronic Information, Yantai University, Yantai Shandong 264005, China
3. Department of Information and Communication, Shanxi Metallurgical Geotechnical Engineering Investigation Co., Ltd., Taiyuan, Shanxi 030002, China