For More Energy-Efficient Dual-Hop DF Relaying Power-Line Communication Systems

Energy efficiency in multihop cooperative power-line communication (PLC) systems has recently received considerable attention in the literature. In order to make such systems more energy efficient, this paper proposes a relaying technique equipped with energy-harvesting capabilities. More specifically, we consider a dual-hop decode-and-forward (DF) broadband PLC relaying system in which the relay exploits the high noise inherent in PLC channels to further enhance energy efficiency; this system will be referred to as DF with energy harvesting (DF-EH). This study deploys, particularly, the time-switching relaying protocol for energy harvesting. An accurate analytical expression for the energy efficiency and a closed-form expression for the average outage probability of the proposed system are derived and then verified with Monte Carlo simulations. For the sake of comparison and to highlight the achievable gains, we also analyze the energy-efficiency performances and the average outage probabilities of the conventional DF relaying system, i.e., without energy harvesting, as well as that of the direct-link approach. Furthermore, various frequency selection and power allocation strategies, namely, optimal frequency selection, random frequency selection, and equal power allocation, exploiting the multiple power cables, are studied. Then, the impact of several system parameters such as the energy-harvesting time factor, various idle power consumption profiles, relay location, power allocation as well as different noise scenarios are examined. The results reveal that the proposed DF-EH system is able to provide energy efficiency improvements of more than 30% compared to the conventional DF relaying scheme. It is also shown that the proposed system with optimal frequency selection performs better at low SNR, whereas at high SNR the equal power allocation based system will have the best performance.