Joint Beamforming and Power Allocation for MIMO Two-Way Relaying Channels

We consider multi-input multi-output (MIMO), two way relaying channels where a pair of multi-antenna users wish to exchange information with the help of a non-regenerative, multi-antenna relay. We propose a joint beamforming and power allocation scheme for all nodes in the network in order to maximise the sum-rate, subject to a total network power constraint. The proposed beamformers first align the channel matrices of the user pair and then decompose the aligned channel matrix into parallel sub-channels. Sum-rate optimising power allocation is proposed to allocate power between all sub-channels and nodes. Simulation results justify that the proposed beamforming scheme significantly outperforms regenerative MIMO one-way relaying, under several different power allocation strategies.