Transmit Power Minimization for Outage-Constrained Relay Selection over Rayleigh-Fading Channels

This letter studies the relay selection scheme for dual-hop decode-and-forward (DF) relay networks over Rayleigh fading channels. In particular, we first provide the problem formulation that minimizes the total transmit power consumption under the constraints of maximum tolerable outage probability and limited power when relay k cooperates. We then derive a closed-form expression of optimal power allocation that solves this optimization problem. Based on the derived closed-form expression, we can quickly select the best relay that consumes the minimum power during the cooperation of transmission.