1. Computer Science, Old Dominion University, 6042 Norfolk, Virginia, United States, 23529 (e-mail: c1wang@odu.edu)
2. Computer Science, Old Dominion University, 6042 Norfolk, Virginia, United States, (e-mail: yxiao002@odu.edu)
3. Computer Science Department, University of Delaware College of Engineering, 137751 Newark, Delaware, United States, (e-mail: xgao@udel.edu)
4. computer science, Shenzhen Institutes of Advanced Technology, 85411 Shenzhen, GUANGDONG, China, 518055 (e-mail: li.li@siat.ac.cn)
5. N/A, Huawei US R&D, Santa Clara, California, United States, (e-mail: jwang86@yahoo.com)