1. Tianyuan Ruixin Communication Technology Co. LtdXi'an710071People's Republic of China
2. Xi'an University of Posts and TelecommunicationsXi'an710121People's Republic of China
3. School of Electronics and InformationNorthwestern Polytechnical UniversityXi'an710071People's Republic of China
4. Department of Electronic and Electrical EngineeringThe University of SheffieldMappin StreetSheffieldS1 3JDUK
5. Department of Systems and Computer EngineeringCarleton UniversityOttawaONCanada