Low-Complexity Nonlinear Interference Estimation Using WRP1-Aided Coarse Step-size Power Profile Estimation

As an emerging optical performance monitoring (OPM) technique, power profile estimation (PPE) has gained significant research attention for its ability to reveal the longitudinal signal power evolution along optical fibers. Among its various applications, nonlinear interference (NLI) noise estimation is particularly promising. In this paper, we propose a low-complexity NLI noise estimation method based on coarse step-size PPE combined with the weighted first-order regular perturbation model (WRP1). The WRP1 model accounts for the correlation between neighboring symbols in the nonlinear operator, thereby mitigating the inaccuracies introduced by coarse step-size power estimation and enhancing overall NLI estimation performance. The proposed method is validated through numerical simulations over a 1000 km transmission system and experimental demonstrations over 500 km and 1200 km optical links. The results demonstrate that the proposed method achieves an estimation error of less than 0.5 dB in both the nonlinear signal-to-noise ratio (SNR_NL) and OSNR penalty, which is comparable to that of conventional fine step-size approaches. Meanwhile, it reduces computational complexity by over 90%, providing a highly efficient solution for practical PPE-enabled NLI estimation.