Non-regenerative multi-antenna two-hop relaying under an asymmetric rate constraint

In this work, the combination of one-way and two-way relaying is examined in a scenario where two multi-antenna nodes exchange information under an asymmetric rate constraint via a half-duplex non-regenerative multi-antenna relay. Two-way relaying overcomes the multiplexing loss of one-way relaying, but additional optimizations are required to fulfill the asymmetric rate constraint. To enable the consideration of suboptimal low-complexity approaches, a hybrid one-way / two-way scheme is suggested which ensures that the asymmetric rate constraint can always be fulfilled. The optimization problem of maximizing the overall sum rate for the considered scenario is formulated and an approach for transceive filter and power optimization considering the asymmetric rate constraint is derived. Simulation results for different link qualities and rate constraints confirm the theoretical considerations and show that the proposed algorithm performs close to the upper bound in case of high asymmetric rate constraints or highly asymmetric channels.