Xu Chaonong received his B.S. and M.S. degrees in Computer Sciences in 1998 and 2001 respectively, both from Hefei University of Technology, China, and his Ph.D. degree from the Institute of Computing Technology, Chinese Academy of Sciences in 2007, also in Computer Science. Dr. Xu joined Tsinghua University as a Postdoctoral Research Associate in 2007. He is now a lecturer in China University of Petroleum, Beijing, China. His research interests include embedded system and wireless sensor networks.To whom correspondence should be addressed. E-mail: cwangzg@cup.edu.cn