Time-Domain Compression Based Analog Feedback for MIMO-OFDM Systems

We investigate the analog feedback of channel state information (CSI) in multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) based wideband wireless communication systems. In MIMO-OFDM systems, the amount of CSI to be fed back grows prohibitively with the number of subcarriers. A straightforward way of reducing the overhead is to feed back a sampled version of the CSI. But sampling based feedback suffers from the aliasing effect in some scenarios. We proved that the aliasing effect can not be eliminated unless the system feeds back more subcarrier channel matrices than the length of the time-domain channel impulse response. To improve the feedback quality and cope with the aliasing problem, we make use of the sparsity of the time-domain channel impulse response and propose a time-domain compression based analog feedback scheme. The proposed scheme overcomes the the aliasing problem, and achieves good performance.