Cooperative interference mitigation with partial CSI in multi-user dual-hop MISO relay channels

This paper considers cooperative eigen beamforming with the use of partial channel information (e.g., transmit correlation) to maximize achievable sum-rate of multi-user dual-hop multiple-input single-output relay channels. By exploiting the transmit correlation in a cooperative manner, the proposed scheme selects a pair of users whose transmit correlation have the largest phase difference of the desired and interference channel from the relay. It is analytically shown that the achievable sum-rate of selected two-users is maximized when the principal eigenvectors of the transmit correlation matrix of the desired and interference channel from the relay are orthogonal to each other. By generating an eigen-beam by the principal eigenvector of the transmit correlation matrix of own desired channel, the proposed scheme can provide the achievable sum-rate comparable to the full channel information-based minimum mean square error beamforming scheme in correlated channel environments. Finally, the proposed scheme is verified by computer simulation.