nothing much. The basic ideas behind cooperative communication can be traced back to the ground breaking work of Cover and El Gamal on the information theoretic properties of the relay channel. This work analysed the capacity of the three-node network consisting of a source, a destination, and a relay. It was assumed that all nodes operate in the same band, so the system can be decomposed into a broadcast channel from the viewpoint of the source and a multiple access channel from the viewpoint of the destination. Many ideas that appeared later in the cooperation literature were first exposited in. However, in many respects the cooperative communication we consider is different from the relay channel. First, recent developments are motivated by the concept of diversity in a fading channel, while Cover and El Gamal mostly analyse capacity in an additive white Gaussian noise channel.