On the DMT-Optimality of Nondynamic DF Relaying in Asymmetric Nakagami Fading Channels

The optimality of nondynamic DF relaying over a general three-node Nakagami fading channel in terms of the diversity-multiplexing tradeoff (DMT) is established. In particular, when the fading of the relay-source link is less severe than that of the relay-destination link, both orthogonal and nonorthogonal DF protocols are shown to be DMT-optimal over certain ranges of the multiplexing gains. It is also shown that when the multiplexing gains are sufficiently high, the DMT of the DF protocols is completely independent of the statistical properties of the relay-destination link.