MU-MIMO Precoding Performance Conditioned by Inter-user Angular Separation

Linear Precoding (LP) schemes are already used in Long Term Evolution (LTE) Multi-User Multiple-Input-Multiple-Output (MU-MIMO) systems. They have low complexity but do not work well in strongly correlated channels, i.e., for closely separated users. Alternatives to LP schemes, like Non-Linear Precoding (NLP) and hybrid precoding schemes were proposed in the standardization phase for 3rd Generation Partnership Project (3GPP) 5G New Radio (NR). The purpose of this paper is to analyze the performance of the existing precoding schemes in spatially correlated MU-MIMO channels, accounting for the angular separation between the users. Although NLP schemes show better results, their complexity is high and as such, hybrid schemes, which combine LP with NLP, can be used to reduce complexity without degrading too much the performance.