A novel low complexity soft-decision demapper for QPSK 8PSK demodulation of DVB-S2 systems

This paper provides an efficient low complexity soft-decision demapper algorithm for computing the log-likelihood-ratios (LLRs) of the 8PSK demodulations in the DVB-S2 standard. The proposed method has linear complexity, avoids the multiple square operations in the classical method and reduces the number of compare-select operations by half compared to traditional LLR computation algorithms. The demapper using the proposed method has been verified on Altera FPGA.