Zhao Yuan, born in 1979. He received his M. S. and B.S. degrees from Communication University of China in 2004 and 2001, respectively. He is now a Ph. D candidate in Beijing University of Posts and Tel- ecommunications. His current research interests in- clude cooperative communications, network coding, and broadcast/multicast. To whom correspondence should be addressed. E-mail: yzhaocq@ gmail, com