Optimal power control for DF cooperative transmission over Rayleigh-fading channels

This paper studies the optimal power allocation required by the source and destination nodes for dual-hop decode-and-forward (DF) relay networks over Rayleigh fading channels. In particular, we first provide the problem formulation that minimizes the expected total transmit power consumption of DF cooperative transmission under the constraints of maximum tolerable outage probability and limited power. We then derive the optimal power allocation due to the convex nature. Meanwhile, the approximately optimal power allocation is provided in the closed-form expression. Based on these results, we further analyze the performance of DF cooperative transmission in comparison to existing transmission schemes.