1. Shaanxi Key Laboratory of Information Communication Network and Security, School of Communications and Information Engineering, Xi’an University of Posts and Telecommunications, Xi’an, China
2. Department of Electrical and Computer Engineering, University of Windsor, Windsor, ON, Canada
3. Information Systems Technology and Design Pillar, Singapore University of Technology and Design, Singapore
4. School of Electrical and Electronic Engineering, The University of Manchester, Manchester, U.K.