Toward real-time adaptive low-rank LMMSE channel estimation of MIMO-OFDM systems

Abstract

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 subspaces of the frequency domain channels at the pilots and non-pilots subcarriers. By using subspace tracking, it is observed that practical LMMSE channel estimation of MIMO-OFDM systems can be feasible.