1. Xi’an Key Laboratory of Advanced Control and Intelligent Process, School of Automation, Xi’an University of Posts and Telecommunications, Xi’an, China
2. School of Communications and Information Engineering, Xi’an University of Posts and Telecommunications, Xi’an, China
3. Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM, USA
4. Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland