Low-complexity approximate LMMSE channel estimation for OFDM systems

A low-complexity linear minimum mean square error (LMMSE) based channel estimator is proposed for orthogonal frequency-division multiplexing (OFDM) systems over frequency-selective channels. Using the law of a large number, we approximate the LMMSE estimator to reduce the numerical complexity of the channel estimation. Our estimator exhibits comparable performance with the LMMSE estimator at low SNR but suffers the performance floor due to the approximation, which are verified by numerical simulations.