Codebook-Based Quantized MIMO Feedback for Closed-Loop Transmit Precoding

Advanced quantization schemes are proposed for closed-loop transmit precoding over correlated multiple-input multiple-output (MIMO) channels in this work. Unlike the conventional schemes that directly quantize the MIMO channel covariance matrix and feed back each quantized matrix element, the proposed schemes quantize the channel covariance matrix by exploiting the common rank-one codebook shared by mobile stations and base stations. Compared to the conventional quantization schemes, the proposed quantization schemes can achieve comparable throughput performance with more than 50% overhead reduction at the cost of affordable increase in computational complexity.