1. Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan
2. Institute of Systems and Information Engineering, University of Tsukuba, Ibaraki, Japan
3. Department of Computer Science, National Yang Ming Chiao Tung University (NYCU), Hsinchu, Taiwan
4. Department of Information and Communication Technology, University of Agder (UiA), Grimstad, Norway