A reduced CSI feedback approach for precoded MIMO-OFDM systems

To obtain the closed-loop capacity of a multiple-input and multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system, channel state information (CSI) is required at the transmitter. To reduce the data rate of CSI feedback, precoding matrix approach has been proposed for MIMO systems in flat fading channels. In this paper, we develop a novel approach for MIMO-OFDM systems in frequency-selective fading channels. The proposed approach exploits the correlation of frequency responses at different subchannels in MIMO-OFDM systems to reduce CSI feedback. It is not only flexible to multiple data stream transmission but also has better performance than the existing approaches.