On the optimality of frequency-domain equalization in DFT-spread MIMO-OFDM systems

In this paper, we compare linear receivers for DFTspread MIMO-OFDM Systems. It is proven mathematically and illustrated by numerical simulations that the advanced DFT RAKE receiver with linear multiuser detection is equivalent to the popular frequency-domain equalization (FDE) with IDFT despreading. This result holds also for multi-antenna systems. As a consequence, broadband wireless transmission chains with high diversity can be implemented with low complexity at the receiving end. The benefit of using the minimum mean-square error (MMSE) criterion in the FDE is also illustrated.