1. School of Information and Communication, Guilin University of Electronic Technology, Guilin, China
2. School of Automation, Guangdong University of Technology, Guangzhou, China
3. State Key Laboratory of Internet of Things for Smart City and the Department of Computer and Information Science, University of Macau, Macau, China
4. Guangxi Key Laboratory of Multimedia Communications and Network Technology, School of Computer, Electronics and Information, Guangxi University, Nanning, China