QRD-Based Precoded MIMO-OFDM Systems with Reduced Feedback

A QRD-based preceded MIMO-OFDM system with reduced feedback is proposed. Unlike the conventional preceding schemes in which the receiver has to feed back information about the channel frequency response of each carrier to the transmitter, the proposed system converts the MIMO-OFDM channel into layered channels by effectively exploiting the QR decomposition of the time-domain channel impulse response matrix. As a result, the receiver in the proposed system only needs to feed back information about one preceding matrix, regardless of the total number of carriers. Furthermore, a computationally efficient implementation scheme is devised for the proposed system. Analytical and simulation results show that the proposed scheme can achieve impressive BER performance compared to the conventional schemes, yet with considerably reduced feedback.