Outage Behavior of MIMO Channels with Partial Feedback and Minimum Multiplexing Gains

The diversity-multiplexing (D-M) tradeoff over a multiantenna channel with resolution-constrained feedback is characterized. The concept of minimum guaranteed multiplexing gain in the forward link is introduced and shown to significantly influence the optimal D-M tradeoff. It is demonstrated that rate adaptation is important in obtaining a high diversity gain even at high rates. The class of extended approximately universal codes is shown to be tradeoff optimal. With codes from this class, the optimal D-M tradeoff is achievable by the combination of a feedback-dependent power controller and only two codebooks. Two novel lower bounds to the optimal D-M tradeoff based on Gaussian coding arguments are presented. These bounds are only asymptotically tight, but can quickly approach the optimal tradeoff even with moderate codeword lengths