Linear Precoding for Space-Time Coded MIMO Systems using Partial Channel State Information

We address the problem of designing a linear precoder for space-time coded multiple-input multiple-output (MIMO) system with partial knowledge of channel state information at the transmitter (CSIT), subject to a total transmit power constraint. Assuming an uncorrelated flat-fading channel and using a maximum-likelihood detector at the receiver, we show that the derived precoder is a function of the noise variance, the eigenvalues of the estimated channel matrix and the eigenvalues of the codeword error matrix. From the results derived herein, it is observed that the power allocation on the eigenvalues of the precoder follows the water-pouring policy. Simulation results are provided to illustrate the significant performance gain achieved by using the proposed precoder even at moderate to large CSIT errors