SMSE precoder design in a multiuser MISO system with limited feedback

We design an end-to-end linear transceiver in the downlink of a multi-user (MU) multiple input single output (MISO) system with quantized channel state information at the transmitter (CSIT). The design minimizes the sum mean squared error (SMSE) under a sum power constraint. The contribution of this paper is two-fold. First, unlike previous approaches, we quantize the channels using mean squared inner product (MSIP) vector quantization (VQ) and derive an SMSE-based algorithm that considers MSIP quantization error as an integral component of the whole system. This decreases the bit error rate (BER) at high signal-to-noise ratio (SNR) and outperforms previously derived MU MISO linear transceivers that exist in the limited feedback literature. Second, we show analytically why the BER, in the high SNR regime, increases if quantization error is not considered.