SINR balancing for non-regenerative two-way relay networks with interference neutralization

In this paper we consider a multi-pair two-way relaying network with two types of relays, namely, smart multi-antenna amplify and forward relays and dumb repeaters. The smart relays are able to perform adaptive linear precoding while the dumb repeaters are only able to forward the received signals. Utilizing an interference neutralization scheme, a closed-form transmit strategy can be computed for our scenario. We derive necessary and sufficient conditions for the feasibility of interference neutralization. This provides interesting insights how to choose system parameters like the number of antennas and the number of relays. When the SINR balancing problem is considered, simulation results show that the interference neutralization solution provides a balance between the computational complexity and the performance when compared to optimal transmit strategies.