A novel iterative receiver for coded MIMO OFDM systems

We propose a novel iterative receiver for coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Starting from the derivation of the optimal minimum mean squared error (MMSE) estimate of the transmitted data, we show that for BPSK and QPSK modulated signals, the soft estimate is a hyperbolic tangent function of the extrinsic information from the soft-input soft-output (SISO) decoder and the decision statistic from the detector. Compared with the conventional iterative receiver which computes the data estimate using only the decoder output, the proposed structure has significant performance gain, for example, it is 2.0 dB better for groupwise space time block coded (GSTBC) MIMO OFDM system at BER of 10^-6, and 1.5 dB better for vertical Bell Lab layered space-time (VBLAST) OFDM system at BER of 10^-5.