Subspace Blind MIMO-OFDM Channel Estimation With Short Averaging Periods: Performance Analysis

Among all blind channel estimation problems, subspace-based algorithms are attractive due to its fast-converging nature. It primarily exploits the orthogonality structure of the noise and signal subspaces by applying a signal-noise space decomposition to the correlation matrix of the received signal. In practice, the correlation matrix is unknown and must be estimated through time averaging over multiple time samples. To this end, the wireless channel must be time-invariant over a sufficient time interval, which may pose a problem for wideband applications. The authors proposed a novel subspace-based blind channel estimation algorithm with short time averaging periods, as obtained by exploiting the frequency correlation among adjacent OFDM subcarriers.