Turbo Demodulation for LDPC-coded High-order QAM in Presence of Transmitter Angular Skew

We analyze demodulation methods for high-order QAM formats in the presence of quadrature angular skew caused by imperfect biasing of the transmitter. Proposed turbo demodulation improves skew tolerance of up to 33-degree angle for an SNR penalty of 1 dB for 1024QAM.