Estimation of Input-Decision Correlation (IDC) for Block-Iterative Generalized Decision Feedback Equalizer

Block-iterative generalized decision feedback equalizer (BI-GDFE) is capable of attaining close to the performance of minimum mean-square-error based iterative soft interference cancellation (MMSE-SIC) receivers with a significant lower complexity. The BI-GDFE however requires an accurate estimate of input-decision correlation (IDC), which is a statistical reliability metric of earlier-made decisions. Till date, the BI-GDFE receiver is applicable only to PSK modulations due to the absence of a methodology to estimate the IDC for higher order modulations. In this paper, we establish the relationship between the MMSE-SIC and BI-GDFE receivers, and propose an algorithm to determine the IDC from the unconditional MMSE-SIC (U-MMSE-SIC). Simulation results show that the BER performance of BI-GDFE with our generated IDC values achieves close to that of MMSE-SIC receivers