Block Diagonalization with user antenna selection for multiuser MIMO systems

Multi-user MIMO (MU-MIMO) improves the system channel capacity by employing the transmission between a base station and multiple user terminals (UT). Block Diagonalization (BD) has been proposed in order to realize MU-MIMO broadcast. The BD algorithm cancels inter-user interference by creating the weights so that the channel matrixes for the other users are set to be zero matrixes. However, when the number of transmit antennas is equals to the total number of received antennas, the transmission rate by the BD algorithm is decreased. In this paper, we propose the antenna selection method to reduce the number of nulls for the other users except an intended user by the BD algorithm. It is verified that the proposed method is effective compared to the conventional BD algorithm, especially, when the number of users is increased with a low bit rate.