LAUSR

In this paper, a power-efficient amplification factor (PEAF) is proposed for reducing the power consumption of the relay station and improving the overall system performance in dual-hop amplify-and-forward (AF) relay networks. In comparison to the conventional amplification factor, the PEAF is designed by minimizing the total transmission power whereas maintaining the required quality of service. Moreover, in accordance with the PEAF scheme, exact closed-form expressions of the probability density function and the cumulative distribution function of the received signal-to-noise ratio are derived with one-way and two-way relaying over Nakagami- ${m}$ frequency-selective fading channels. Monte Carlo simulation is executed to verify these mathematical expressions. Simulation results show that the relay system with the proposed PEAF possesses a lower outage probability and higher energy efficiency in comparison with counterparts of the conventional variable-gain AF relaying.