An MMSE Based Block Diagonalization for Multiuser MIMO Downlink Channels with Other Cell Interference

In this paper, we develop a minimum mean-squared error (MMSE) based block diagonalization (BD) algorithm for multiuser multi-input multi-output (MIMO) broadcast systems where each user has more than one antenna in the presence of other cell interference (OCI). Unlike the conventional BD based multiuser MIMO transmission schemes which suffer from the noise enhancement problem as eliminating all multi-user interference (MUI) completely, the proposed scheme attempts to suppress the MUI with a consideration of the OCI plus noise and employs an additional residual interference suppression process based on an MMSE criterion. As a result, the proposed scheme improves the signal-to-interference-plus-noise ratio (SINR) at each user's receiver compared to conventional BD based schemes. Simulation results demonstrate that the sum rate performance of the proposed algorithm is always better than that of the conventional BD based algorithms for various OCI configurations.