Energy Efficiency Optimization for SWIPT-Enabled Cooperative Relay Networks in the Presence of Interfering Transmitter

Recently, energy harvesting via radio frequency (RF) signals has gained significant attention from academe and industry as a suitable solution to powering energy constrained relay nodes in cooperative networks. The ability to maximize the energy efficiency of such cooperative networks is still a critical issue because an inefficient cooperative network can affect certain requirements for the system quality of service (QoS). In this letter, we study the energy efficiency performance of a simultaneous wireless information and power transfer (SWIPT)-enabled cooperative relay network in the presence of an interfering transmitter (IT). The SWIPT-enabled relay network is subjected to interference, which affects the quality of the signal received at both the relay node and the destination node. We consider two scenarios: 1) when the RF energy that the relay can harvest from the interference signal is assumed to be negligible and 2) when the relay harvests the RF energy from both the source and the IT transmissions. We derived the optimal transmitted source's power for each scenario and obtained the suboptimal power splitting and energy consumed factors by running extensive simulations. Then, we proposed a new energy-saving power splitting relaying (ES-PSR) protocol.