Performance Analysis of Multi-Branch Decode-and-Forward Cooperative Diversity Networks over Nakagami-m Fading Channels

In this paper, the performances analysis of cooperative-diversity networks using adaptive decode-and-forward (DF) relaying over independent non-identical flat Nakagami-m fading channels is investigated. We derive closed-form expressions for the error probability, outage probability and average channel capacity, and analyze their dependence on the channel parameters. In adaptive DF relaying, among M relays that can participate, only C relays (C les M), with good channels to the source, decode and forward (retransmit) the source information to the destination. Then, the destination combines the direct and the indirect signals using maximum ratio combining (MRC) technique. We derive a closed-form expression for the the moment generating function (MGF) of the total signal-to-noise ratio (SNR) at the destination node. Then, we find a closed-form expression for the probability density function (PDF) of the total SNR at the destination. This PDF is used to derive the closed-form expressions of the performance metrics. Computer simulations are used to validate our analytical results. Results show the significant performance improvement due to the use of the adaptive DF cooperative diversity. Also, results indicate that increasing the number of relays will not always decrease the outage probability.