1. School of Internet of Things, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, P. R. China
2. Key Laboratory of Ministry of Education, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, P. R. China
3. Xuzhou XCMG Excavator Machinery Co., Ltd., Xuzhou, Jiangsu 221100, P. R. China
4. College of Telecommunications & Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, P. R. China