Lattice Reduction-Aided Preprocessing and Detection Techniques for MU-MIMO in Broadcast Channel

Block diagonalization (BD) is one of the most effective preprocessing techniques for multiuser multi-input multi-output (MU-MIMO) systems. By using BD the MU-MIMO broadcast channel can be decomposed into multiple parallel independent SU-MIMO channels through two singular value decomposition (SVD) operations. Complex lattice reduction (CLR) is another technique that aims to enforce orthogonality between the columns of the channel matrix and reduce its size as well. In this paper, only the first SVD is adopted to obtain parallel SU-MIMO channels with zero interference, the orthogonalization and size-reduction work are left for the CLR algorithm so that a modification of the channel matrix is carried out, resulting in a better precoding and detection performances. Simulation results show that the proposed algorithm greatly outperforms conventional BD detection and linear precoding techniques.