1. School of Management, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
2. Jiangsu Key Laboratory of Wireless Communications, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
3. Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks, Nanjing University of Posts and Telecommunications, Ministry of Education, Nanjing 210003, China
4. School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
5. School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210003, China