A fast forward/backward semi-blind channel estimation for MIMO STC-OFDM systems

In the study, we propose an efficient subspace-based semiblind channel estimation for multiple-input-multiple-output (MIMO) space-time code (STC) orthogonal frequency-division multiplexing (OFDM) systems. We first proposed a forward-backward estimation (FBE) method which can improve the channel estimation accuracy by using both the forward and backward receiving data. Then, based on the symmetric property of the forward and backward smoothed correlation matrix, we develop a fast forward-backward (FFB) estimation method which estimates the noise subspace by performing eigen-decomposition of two half dimensionality sub-matrices obtained from the forward and backward smoothed correlation matrix. FFB achieves the same performance as the FBE but only requires one-fourth computation complexity of FBE. Computer simulations demonstrate the effectiveness and accuracy in channel estimation of the proposed FFB for the MIMO STC-OFDM systems.