Linear Dispersion Codes for MIMO Channels with Limited Feedback

In this paper, we propose linear dispersion codes (LDCs) for multiple-input multiple-output (MIMO) channels with a prescribed amount of feedback. The proposed scheme selects the LDC from a set of LDCs that minimizes the error probability based on the instantaneous channel conditions. The determination of the best set of LDCs, i.e., the one that minimizes the average error probability, is described as a constrained optimization problem. While this problem appears to be intractable in general, for certain parameters we present good sets of LDCs, obtained from an iterative optimization algorithm. Results are given for rate-one LDCs only, but this restriction can be removed. Computer simulations show that the proposed schemes outperform previously reported comparable schemes for the same number of feedback bits.