Xu Chao-Nong Ph.D. candidate at Institute of Computing Technology, Chinese Academy of Sciences. His research interests include wireless sensor networks and embedded system.E-mail: xu_chaonong@ict.ac.cn. ZHAO Lei Ph. D. candidate at Institute of Computing Technology, Chinese Academy of Sciences. His research interests include wireless sensor network and VLSI design. XU Yong-Jun Ph.D. candidate at Institute of Computing Technology, Chinese Academy of Sciences. His research interests include wireless sensor networks and low power system.E-mail: xyj@ict.ac.cn. LI Xiao-Wei Professor at Institute of Computing Technology, Chinese Academy of Sciences. His research interests include VLSIO/SC testing and embedded system.E-mail: lxw@ict.ac.cn.