1. Innovative Information Industry Research Center (IIIRC), School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China
2. Shenzhen Key Laboratory of Internet Information Collaboration, School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China
3. Department of Computer Science and Information Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan
4. Department of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan