Joint Beamforming and Power Management for Nonregenerative MIMO Two-Way Relaying Channels

We consider multiple-input-multiple-output (MIMO) two-way relaying channels where a pair of multiantenna users wishes to exchange information with the help of a nonregenerative multiantenna relay. A low-complexity joint beamforming and power management scheme is proposed. The proposed beamformers first align the channel matrices of the user pair and then decompose the aligned channel into parallel subchannels. Two power management issues, i.e., power allocation and power control, are addressed in this paper. First, sum-rate optimizing power allocation is proposed to allocate power between all subchannels and nodes. Second, quality of service (QoS) satisfying power control is proposed to minimize the total transmission power in the network. Simulation results justify that the proposed joint beamforming and power management scheme delivers better sum-rate performance or consumes lower transmission power when compared with existing schemes.