VBLAST Detection Algorithms Utilizing Soft Symbol Estimate and Noncircular CAI

We address the problem of error propagation inherent in the VBLAST detection process. To this end, two improved VBLAST schemes are proposed. The first one replaces hard decision with soft decision; whereas the other also utilizes soft symbol estimate, but in the meantime exploits the noncircular nature of the residual co-antenna interference (CAI) and noise, it involves refining the error criterion and nulling filter. Simulation results show that both schemes outperform their conventional counterpart and utilization of noncircular CAI significantly alleviates the error propagation problem and improves the performance of the VBLAST detection.