Channel estimation accuracy has a significant impact on the performance of multiple-input multiple-output (MIMO) wireless communication systems due to cochannel interferences in MIMO channels. An improved channel estimation algorithm is presented in this paper for MIMO systems using orthogonal frequency division multiplexing (OFDM) technique based on the least squares (LS) algorithm. The proposed algorithm employs the noise correlation in order to improve the LS estimator by estimating and suppressing the noise in signal subspace. Without knowledge of the statistical parameters of channel, the new proposed algorithm attains a significant improvement in performance in comparison with that of the regular LS estimator and is also robust to the number of antennas in transmit and receive sides.

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