Energy efficiency and sum-rate maximization in MIMO two-way relay networks

This paper compares energy efficiency of a multiple-input multiple-output two-way relay network while applying two different precoder design methods. The cooperation part of this study consists of a single amplify and forward (AF) two-way relay node equipped with multiple antennas. In order to compare the efficiency of the proposed schemes, energy efficiency (EE) is defined as the ratio of total bits of transmitted data to the total amount of consumed energy. In the first scenario, transceivers precoders are designed based on EE-maximization under some constraints on the transmit power of each node and quality of service (QoS) guarantee. The second scenario introduces an energy efficient precoder design at the transceiver nodes which maximizes total sum-rate under transmit power and QoS constraints. Additionally, an appropriate relay precoder matrix is designed in order to eliminate self-interference by applying zero-forcing (ZF) criterion in both scenarios. Two alternating algorithms are proposed to optimize transceivers and relay precoder matrices simultaneously. Simulation results are provided in order to evaluate and compare the performance of the proposed schemes which imply the efficiency of EE-maximization method.