Conditions for Cooperative Transmission on Rayleigh Fading Channels

We consider a system of two nodes transmitting to an access point on quasi-static Rayleigh fading channels. We use signal-to-noise ratio (SNR) thresholds to characterize the requirements of each node, in terms of throughput and reliability, and we study their impact on outage probability. Given the average quality of the uplink channels, we formulate conditions on the SNR thresholds for decode-and-forward cooperation to be beneficial; that is, for nodes to experience an improvement in their outage probabilities if they switch from non-cooperative to cooperative transmission. We derive analytical bounds and propose tight approximations, which can be applied by the nodes to make decisions in favor or against cooperation.