Abstract:The overlapping frequency domain equalization (O-FDE) in digital signal processing (DSP) is frequently employed to provide dispersion compensation in long-distance coherent fiber optical communications. However, the change in overlapping symbol length that occurs during the processing of the O-FDE algorithm will typically be influenced by the decision and zero filling of the last subblock, which is harmful to the robustness of the O-FDE algorithm. In this study, with a thorough robustness analysis on changing overlapping symbol length, we present a novel method for decision and zero filling of the last subblock and examine the correspondingly resulting error vector magnitude (EVM) and symbol error ratio (SER) under different values of optical signal-to-noise ratio (OSNR), chromatic dispersion, and overlapped symbol lengths.