A New Precoding Scheme for Constructive Superposition of Interfering Signals in Multiuser MIMO Systems

In a multiuser multiple-input-multiple-output system, handling inherent co-channel interference has been a major problem for reliable transmission. Most previous closed-form linear precoding schemes are based on channel inversion (CI). Several extended studies have attempted to retain power gain from already existing interference, instead of nulling it while still based on CI. However, there has not been a study on manipulating the interference to maximize the gain. In this letter, we propose a new precoding scheme for a base station to manipulate both a desired signal and interfering signals such that the desired signal can be superimposed with the interfering signals. In our approach, a Jacobian-based algorithm is applied to improve the performance. Simulation results demonstrate that the proposed scheme achieves improved robustness. Furthermore, we show that robustness becomes stronger with an increasing number of co-scheduled users in the phase-shift keying-based systems.