An iterative semi-blind channel estimation with decision-directed for OFDM systems in fading channels

For the purpose of suppressing noise and improving the accuracy of channel estimation, it is natural to consider adding pilots. However, this leads to more system overhead. An iterative semi-blind channel estimator is presented for orthogonal frequency-division multiplexing (OFDM) systems operating in frequency-selective channels. This proposed channel estimation adds pilots to the data symbols and hence does not require any additional bandwidth for its implementation. The price is equivalent to a loss in the signal to noise ratio (SNR) at the receiver input. For the purpose of improving the MSE performance, an iterative decision directed channel estimation is proposed. Simulation results give the performance comparison between the proposed iterative semi-blind channel estimation and the conventional channel estimation. The proposed channel estimation can save the overhead of OFDM systems, and by suitably choosing parameters it also can give a more accurate channel estimate than the conventional least-mean (LS) channel estimation.