On the ergodic capacity of cooperative-diversity networks with decode-and-forward relaying over Nakagami-m fading channels

Cooperative diversity techniques have emerged as promising solutions to combat the deleterious effects caused by multipath fading. The main advantage of this technique is that the diversity gain can be achieved without installing multiple antennas at the transmitter or the receiver. In this paper, we study the ergodic capacity performance of cooperative communication systems with decode-and-forward (DF) relaying protocol over Nakagami-m fading channels. Specifically, the ergodic capacity over both independent identically distributed (i.i.d.) fading channels and independent non-identically distributed (i.n.d.) fading channels are investigated. We first explore the ergodic capacity over i.i.d. fading channels, and then derive the tight bounds for the ergodic capacity at the regime of low signal-to-noise (SNR) and high SNR, respectively. Further, we obtain an exact closed-form analytical expression of the ergodic capacity over i.n.d. fading channels. Finally, the Monte-Carlo simulations are provided to verify the tightness of the proposed bounds. The theoretical results obtained are instrumental to the future cooperative-diversity network modeling and design.