1. Department of Computer Science and Engineering, The Chinese University of Hong Kong
2. Department of Computer Science and Engineering, The Chinese University of Hong Kong: michael, wzong
3. Xian Institute of Space Radio Technology, 150 Wei Qu West Street, Changan District, P.O. Box 165, Xian, 710100 PRC
4. School of Electrical & Electronic Engineering, Newcastle University, UK
5. Department of Electrical and Electronic Engineering, UCL, London, UK