1. College of Internet of Things, Nanjing University of Posts and Telecommunications, Nanjing, China
2. College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, China
3. Faculty of Electrical Engineering and Information Technology, RWTH Aachen University, Aachen, Germany
4. International Research Institute of Disaster Science, Tohoku University, Sendai, Japan