Iterative decoding on soft information for virtual layered space-frequency receivers

In this paper, we propose an iteration scheme for the virtual layered space frequency communication architecture. The architecture enables the decoding of the transmitted orthogonal frequency division multiplexing (OFDM)-QPSK signals even if the number of spatial multiplexed layers is twice that of receiving antennas over multipath fading channels. In the proposed iteration scheme, the MAP decoder and detector exchange soft information on the virtual channel. Using the soft informations, the architecture achieves much higher performance with lower computational complexity compared to maximum likelihood detection (MLD) even when the punctured code is used. Consequently, a gain of 4.5 dB can be achieved at a BER of 10^-3 compared to that achieved with the MLD in the 4 × 2 MIMO-OFDM system when the rate 3/4 punctured code is used. The performance of the proposed architecture is verified by carrying out computer simulations.