Decision-Aided, Pilot-Aided, Decision-Feedback Phase Estimation for Coherent Optical OFDM Systems

We propose two phase estimation methods for coherent optical orthogonal frequency-division multiplexing (OFDM) systems, the decision-aided (DA) plus pilot-aided (PA) scheme and DA plus decision feedback (DF) scheme. We further investigate the combinations of DA, PA, and DF in a simulated 40-Gb/s single polarization system.
${\rm DA}+{\rm PA}$
helps to increase the phase noise tolerance of DA and reduce the overhead of PA, while
${\rm DA}+{\rm DF}$
reduces the overhead to zero and achieves the best performance with one more step of estimation, compensation, and demodulation.