Channel estimation for D-BLAST OFDM systems

The Diagonal Bell Laboratories Layered Space-Time (D-BLAST) structure offers a low complexity solution to realize the attractive capacity of multiple-input and multiple-output (MIMO) systems. We apply D-BLAST in orthogonal frequency division multiplexing (OFDM) systems and address the issue of channel estimation. Different from other MIMO-OFDM, where symbols at all tones are always available for decision-directed channel estimation, in D-BLAST OFDM, we update estimated channel parameters each time a layer is detected with a least square (LS) approach, using a pieced combination of received signals at previous and current OFDM blocks. The initial estimate is further refined by a robust estimator to exploit the time correlation of channel parameters among OFDM blocks. Computer simulation results show the performance improvement over block-wise channel estimation. It is also shown that D-BLAST with proposed channel estimation is robust to fast fading of channel parameters.