1. Engineering Research Center of Digital Forensics, Ministry of Education, the School of Computer Science, Nanjing University of Information Science and Technology, Nanjing, China
2. Institute of Artificial Intelligence, Guangzhou University, Guangzhou, China
3. National Engineering Research Center for Mobile Network Technologies, Beijing University of Posts and Telecommunications, Beijing, China
4. Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, USA