中文摘要：

Tian Xinguang was born in 1976. He received the B.S., M.S. and Ph.D. degrees in 1998, 2001 and 2005, respectively. He is an assistant professor in Beijing Jiaotong University. His main research interests are digital signal processing and information security. E-mail： tianxinguang@163.com Liu Xin was born in 1969. She now is Ph.D. and an assistant professor in Beijing Jiaotong University. Her research interests include signal processing and network communications. Chen ttong was born in 1968. She now is a senior engineer in Beijing Jiaotong University. Her research interests include computer application and network communication Duan Miyi was born in 1953. He received the Ph.D. degree in computer science from Magdeburg University, Germany, in 1995. He now is a professor and Ph.D. supervisor in Institute of Computing Technol- ogy, Chinese Academy of Sciences. He is a senior mumber of the China Computer Federation. His research interests include wireless telecommunication and network security.