Linear Selective Channel Inversion Technique for Multi-User MIMO Systems

Multi-user MIMO systems have the potential to combine the high capacity achievable with MIMO processing with the benefits of space-division multiple access. Although recent theoretical results show that the sum capacity grows linearly with the minimum of the number of antennas and users, the sum rate of channel inversion does not due to the large spread in the singular values of the channel matrix. In this paper, we introduce a suitably modified channel inversion technique which randomises the phases of the channel to mitigate the impact of the ill-conditioned channel and obtains near-sum-capacity of the multi-user MIMO systems. The proposed technique not only achieves significant improvement over conventional linear precoding techniques at all signal-to-noise ratios (SNRs) but also outperforms the convolutional precoder at low SNRs.