Linear Precoding Based on Correlation Rotation for the Multi-User MIMO Downlink

This paper investigates the potential of exploiting interference power in order to enhance the performance of multiple input multiple output (MIMO) broadcast systems using phase shift keying (PSK) modulation. Towards this end, the proposed linear precoding aims at adaptively rotating, rather than zeroing, the correlation between the MIMO sub-streams depending on the transmitted data, so that the signal of interfering transmissions 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). It is shown by means of theoretical analysis and simulations that by using interference as a source of green energy the proposed technique outperforms conventional precoding.