Jointly Optimal Precoding/Postcoding for Colored MIMO Systems

The problem of designing a jointly optimal linear precoder and decoder for a multiple-input multiple-output (MIMO) channel has received much interest recently. However, most existing works only deal with white input signal. When the input signal is colored, prewhitening and its inverse operation are often applied prior to precoding and after decoding, respectively. Consequently, the precoder and decoder are no longer optimal with respect to the original colored signal. In this paper, we propose a closed-form solution for optimal linear precoder and decoder for colored input signal. Our approach is based on minimizing the symbol mean squared error under an average output power constraint, and is applicable to both MIMO flat fading and frequency selective fading channels. Simulations show the advantage of our solution over prewhitening-based method