1. School of Computer and Information Engineering, Chuzhou University, Chuzhou, China
2. Department of Communications and Networking, School of Electrical Engineering, Aalto University, Espoo, Finland
3. Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland
4. School of Information and Technology, Kunming University, Kunming, China
5. School of Systems Information Science, Future University Hakodate, Hakodate, Japan