On throughput gains by exploiting green interference power in the multi-user MIMO downlink

A sum rate and throughput enhancing closed form precoding scheme is proposed for multiple input multiple output (MIMO) broadcast systems. The technique proposed utilizes interference judiciously to enhance the received signal energy and improve performance. Instead of completely eliminating interference as in conventional precoders, the proposed adapts the angle of correlation between the MIMO sub-channels, so that interference is aligned to the signal of interest at each receive antenna. By doing so, the co-channel interference (CCI) is always kept constructive and the received signal to interference-plus-noise ratio (SINR) delivered to the mobile units (MUs) is enhanced without the need to invest additional signal power per transmitted symbol at the MIMO base station (BS). By exploiting this important source of green signal power, the presented results and analysis demonstrate significant benefits in the performance of the MIMO downlink.