Outage performance of an energy-efficient relaying protocol over Nakagami fading channels

This paper proposes a new Clipped Gain (CG) relaying protocol that takes advantage of the first-hop channel state information available at the relay to efficiently use the transmit power. The CG allows the relay to transmit only when the first-hop signal-to-noise ratio(SNR) is above the outage threshold, otherwise, relay transmission is stopped as it leads in that case to an outage. Closed-form expressions of CG outage probability over Nakagami fading channels are derived. The outage performance of the CG protocol is compared to those of practical Amplify-and-forward protocols including Fixed Gain (FG) and Variable Gain (VG) protocols, and a Decode-and-forward (DF) protocol. Numerical results show that the CG outperforms the other practical AF protocols and even approaches DF outage performance at low SNR while maintaining low complexity of an AF protocol.