1. Department of Information Science and Technology, Qingdao University of Science and Technology, Qingdao, China
2. Guangxi Key Laboratory of Digital Infrastructure, Guangxi Information Center, Nanning, China
3. School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo, China
4. Department of Electrical and Computer Engineering, University of Victoria, Victoria, BC, Canada
5. School of Computing, Engineering and Mathematics, Western Sydney University, Kingswood, NSW, Australia