Energy efficiency optimization in energy harvesting cooperative relay systems

In future cellular systems, some energy harvesting (EH) powered relaying nodes may be deployed to achieve energy saving and quality of service (QoS) improvement, while base stations still get energy from power grid to ensure basic coverage requirements. In this paper, we focus on maximizing the energy efficiency (EE) of the non-EH source with the help of the EH decode-and-forward (DF) relaying nodes. Taking non-ideal circuit power into consideration, we first formulate the energy efficiency optimization problem of the relaying system and prove it is quasiconvex. And then we propose an energy-efficient transmission policy (EETP) with/without diversity by combining the power allocation and sleep mode in both the source and the relay. Numerical results show that the proposed scheme can help saving energy effectively while meeting the average throughput requirement.