MMSE-Based Optimization of Perturbation Coefficients Quantization for Fiber Nonlinearity Mitigation

In perturbation-based digital fiber nonlinearity mitigation methods, such as pre-distortion and post-equalization, quantization of perturbation coefficients is employed to reduce the computational and implementation complexity. However, quantization introduces errors, which results in performance penalties. By analyzing the occurrence probability of the perturbation coefficients, an MMSE-based optimization of perturbation coefficients quantization is proposed and demonstrated in ultra-large-area-fiber transmission systems with a 36Gbd DP-16QAM modulation format. Compared to conventional uniform quantization schemes, a significant reduction in quantization errors has been realized for both the real and imaginary parts of the perturbation coefficients. Compared with the nonquantization case, computational term reduction by a factor of 50 is achieved in 2400 km ULAF transmission with < 0.2 dB Q degradation. For the same Q improvement, optimized quantization scheme further reduce the computational term by 50% compared to that of the uniform quantization method. We also analyze the tolerance to link dispersion.