1. School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China
2. School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China and with the Henan International Joint Laboratory of Intelligent Health Information System, the National Telemedicine Center, the National Engineering Laboratory for Internet Medical Systems and Applications, Zhengzhou 450001, China, and the School of Electrical Engineering, Korea University, Seoul 02841, Korea
3. National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China, and also with the Purple Mountain Laboratories, Nanjing 211100, China
4. School of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, China
5. Department of Applied Informatics, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland, and also with the Departement of Engineering, Nottingham Trent University, Nottingham NG1 4FQ, UK