Common phase error mitigation based on decision directed data subcarriers in OFDM systems

In this paper, we propose a method using decision-directed data subcarriers to estimate and correct common phase error. This method involves two phases: estimating pilot CPE for the current symbol using pilot subcarriers and estimating the previous symbol’s CPE using data subcarriers. To derive the decision directed CPE, LLR values from the previous symbol’s data subcarriers are decoded, modulated, and compared with the previous symbol. And, threshold values specific to each QAM constellation were used to select data subcarriers, preventing CPE distortion from incorrectly detected data. The DD-CPE estimated from selected data subcarriers introduces a one-symbol delay but provides more accurate CPE values compared to pilot CPE due to the increased use of data subcarriers. Simulation results indicate that for HT-MM MCS7 frame, DD-CPE estimation gains 0.59dB compared to pilot CPE estimation but experiences a 0.35dB performance loss compared to the ideal genie CPE estimation.