Energy Efficiency Analysis of Two-Way DF Relay System With Non-Ideal Power Amplifiers

The energy efficiency (EE) problem of a two-way decode-and-forward relay system with three nodes is studied. The maximization of the EE is done by jointly optimizing the transmission time and power of each node, assuming non-ideal power amplifiers (PAs) and considering that data to be delivered is delay constrained. Theoretical analysis and numerical results show that the joint optimization of both parameters provides better EE than the equal allocation of time with independent optimization of transmission power. Moreover, it is observed that the use of non-ideal PAs and the increase in the downlink-to-uplink data ratio decrease the EE of the relay system under study.