2021 Volume 10 Issue 5 Pages 212-218
This letter proposes a new precoding design scheme to improve the null-space expansion (NSE) for multi-user massive MIMO systems. In NSE, steering many nulls based on past channel state information (CSI) significantly improves inter-user interference (IUI) suppression capability in a time-varying channel environment. However, extensive nullification consumes a part of the degree of freedom (DoF) resulting in the degradation of the desired signal gain. Our new proposal predicts the desired user’s channel state and derives the precoding weight to compensate for that loss. Computer simulation verifies the improved signal-to-interference-plus-noise power ratio (SINR) performance.