Optimal transmission and feedback design for OFDM/MIMO systems in frequency selective fading channels with limited feedback

In this paper, we propose a systematic design framework to deal with the problem of partial CSIT feedback for MIMO-OFDM systems. Based on the framework, we obtain the optimal transmission and CSI feedback strategy given the limited CSI feedback constraint. We found that the design problem is very similar to the classical vector quantization problem with a modified distortion metric. We derive a computational efficient algorithm to search for the design of the optimal transmission and feedback strategy. We found that with a small number of bits for CSIT feedback, there is already significant capacity gain in the MIMO-OFDM systems. For illustration, we compare our proposed scheme with some regular adaptation schemes (designed for perfect CSIT). We found that systems designed for perfect CSIT performs poorly when the feedback channel can only support a limited number of bits. This justifies the importance of designing the system matched to the limited feedback constraint