Power optimization of Decode-and-forward assisted ARQ relaying

In this paper we investigate the performances of Decode-and-forward (DF) assisted by automatic repeat request (ARQ) relaying over Rayleigh fast fading channel. We derive a tight asymptotic approximation of the outage probability at high signal-to-noise ratio(SNR) regime. Furthermore we formulate an optimization problem aiming at achieving a target outage probability with an optimum allocation of the power budget depending on the relative position of the relay with regard to source and destination.