To whom correspondence should be addressed. E-mail: lw. bupt@ gmail.com Liu Wei, born in 1984. He received his B.S. degree from School of Telecommunication Engineering of Beijing University of Posts and Telecommunications in 2006. He is currently working towards the M.S. degree in communication and infonnation systems in Beijing Uni- versity of Posts and Telecommunications. His research in- terests lie in the areas of wireless communications and networking, including the routing protocol design and perfonnance analysis for wireless communication networks, with a special emphasis on wireless mobile relay networks for reliable, energy-efficient and cooperative communications.