1. School of Cyber Engineering, Xidian University, 47905 Xian, Shaanxi, China, (e-mail: Xuyangjing91@163.com)
2. School of Cyber Engineering, Xidian University, 47905 Xian, Shaanxi, China, (e-mail: 1299634339@qq.com)
3. Department of Communications and Networking, Aalto University, Espoo, Helsinki area, Finland, (e-mail: zhengyan.pz@gmail.com)
4. ECE, University of Alberta, Edmonton, Alberta, Canada, (e-mail: wpedrycz@ualberta.ca)