Regularized channel inversion with quantized feedback in down-link multiuser channels

We consider regularized channel inversion (RI) precoding in the multiuser multiple input multiple output (Mu-MIMO) broadcast channels. To make the RI operate in quantized channel feedback condition, we analyze the quantization error variance and its effect on the signal to interference plus noise power ratio (SINR) of the user signals. The regularization parameter ¿ is optimized to balance the additive noise, the multiuser interference and the interference due to the quantization error and to maximize SINR. Analysis and simulations show that regularization enhances the performance of zero forcing beam forming (ZFBF) over the whole signal to noise power ratio (SNR) range. This is contrasting to the perfect channel status information (CSI) case, where the enhancement is observed in the low SNR region.