Iterative Biased MMSE Detections for DSTTD-OFDM Systems Over Time-Varying Multipath Channels

In this paper, the authors propose iterative Biased Minimum-Mean-Squared-Error (BMMSE) detection schemes for Double Space-Time Transmit Diversity (DSTTD)-Orthogonal Frequency Division Multiplexing (OFDM) systems over time-varying multipath channels. The time-varying effects cause Inter-Carrier Interference (ICI) and destroy the orthogonality of each STTD unit, considerably degrading system performance. To mitigate these impairments, they first estimate all transmitted symbols temporarily using Sorted-QR-Decomposition (SQRD)-based Decision-Feedback Detection (DFD) considering the partial ICIs. Next, the significantly dominant ICI terms are eliminated with the help of the estimated symbols in the previous step.