Reduced-rank LS Channel Estimation for MIMO-OFDM Systems

In this paper reduced-rank least–squares (rr-LS) channel estimation for MIMO-OFDM systems is presented. Conventional LS solution is firstly introduced and a low complexity per-subcarrier based version derived. Then, estimation mean square error is shown to improve when a reduced-rank approach is adopted. In that case, MIMO channel estimation is refined in time domain by setting to the real value the length of the estimated channel. It results that rr-LS represents a convenient choice performing close to the linear MMSE solution.