Adaptive low-rank MIMO-OFDM channel estimation

For the practical LMMSE channel estimation of MIMO-OFDM systems, the high computational complexity of LMMSE needs to be eliminated. In this study, we develop a low-complexity, generalized low-rank LMMSE channel estimator for MIMO-OFDM systems using comb-type pilots. The estimator utilizes the relationship between the sub-spaces of the frequency domain channels at the pilots and non-pilots subcarriers. By then using subspace tracking, if is observed that practical LMMSE channel estimation of MIMO-OFDM systems can be feasible.