Control overhead reduction method employing frequency correlation for MU-MIMO-OFDM THP with user scheduling

This paper proposes a method for control overhead reduction by employing frequency correlation for MU-MIMO-OFDM THP with semi-orthogonal user selection (SUS). The feature of the proposed approach is to reduce the control overhead generated by subcarrier-based user selection results by limiting the sub-carriers according to the frequency correlation. The motivation behind this approach comes from the fact that the same user selection results could be applicable to neighboring subcarriers by increasing the frequency correlation. A simple theoretical formula containing a parameter for a power delay profile is adopted to facilitate the derivation of the frequency correlation. Frequency correlation is achieved by generating the power delay profile by averaging the channel state information (CSI) over multiple transmit antennas with the aid of MU-MIMO. Moreover, our efficient method, which ensures the benefit of ordering by reusing the SUS results for the ordering calculation, is adopted to coordinate SUS and THP ordering. The effectiveness of the proposed method is demonstrated in terms of both system capacity and control overhead reduction by comparing it with the subcarrier-based approach.