Low-complexity RBD precoding method for downlink of multi-user MIMO system

Many practical downlink multi-user multiple-input multiple-output (MIMO) linear precoding methods have been proposed recently. The block diagonalisation (BD) method has more advantages when each user is equipped with multiple receive antennas. However, BD has poor performance at the low and medium SNR regime with no consideration of noise. Hence, the regularised block diagonalisation (RBD) method has been proposed, which also has a high computational complexity for using singular value decomposition to suppress multi-user interference and noise. Proposed is a novel method of Cholesky factorisation for the RBD method, which can reduce computational complexity effectively without performance loss. Analysis and simulation results show the effectiveness of the proposed method.