Mitigating the Impact of Noise on Nonlinear Frequency Division Multiplexing

Abstract

In the past years, nonlinear frequency division multiplexing (NFDM) has been investigated as a potentially revolutionary technique for nonlinear optical fiber communication. However, while NFDM is able to exploit the Kerr nonlinearity, its performance lags behind that of conventional systems. In this work, we first highlight that current implementations of NFDM are strongly suboptimal, and, consequently, oversensitive to noise: the modulation does not ensure a large minimum distance between waveforms, while the detection is not tailored to the statistics of noise. Next, we discuss improved detections strategies and modulation techniques, proposing some effective approaches able to improve NFDM. Different flavors of NFDM are compared through simulations, showing that (i) the NFDM performance can be significantly improved by employing more effective detection strategies, with a 5.6 dB gain in Q-factor obtained with the best strategy compared to the standard strategy; (ii) an additional gain of 2.7 dB is obtained by means of a simple power-tilt modulation strategy, bringing the total gain with respect to standard NFDM to 8.3 dB; and (iii) under some parameters range (rate efficiency η≤30%), the combination of improved modulation and detection allows NFDM to outperform conventional systems using electronic dispersion compensation.

Serial and parallel convolutional neural network schemes for NFDM signals

“…Nonlinear frequency division multiplexing (NFDM) is a multiplexing technique borrowed from orthogonal frequency division multiplexing (OFDM) in convectional fibre optic communication, in which the linear spectrum of OFDM is replaced by a nonlinear spectrum 3 and becoming popular in recent years 6 , 37 – 41 . The modulation is usually applied to the continuous part of the nonlinear spectrum directly, but modulating (b-modulation) has also been used as it results in pulses with well defined temporal windows 7 , 42 – 46 .…”

Serial and Parallel Convolutional Neural Network Designs for NFDM Signals

“…Nonlinear frequency division multiplexing (NFDM) is a multiplexing technique borrowed from orthogonal frequency division multiplexing (OFDM) in convectional fibre optic communication with a replacement of the linear spectrum with a nonlinear spectrum 3 and becoming popular in recent years 6,[17][18][19][20][21] . The modulation is usually applied to the continuous part of the nonlinear spectrum Q(λ ) directly, but modulating b(λ ) (b-modulation) has also been used as it results in pulses with well defined temporal windows 7,[22][23][24][25][26] .…”

Fixed-point realization of fast nonlinear Fourier transform algorithm for FPGA implementation of optical data processing

“…8,9 But similar to the DBP-type methods, the signal processing based on the NFT algorithms suffers from the large numerical complexity, power-sensitive numerical errors, 13 and complicated signal-dependent noise affecting our NF information carriers along their evolution. 10,[13][14][15] We note that up to the moment, in addition to a multitude of theoretical studies, 9,15 there exists a number of experimental demonstrations of NFT-based transmission systems, 16 including recently introduced efficacious b-modulation method, 17,18 that incorporates the continuous NF spectrum part. In fact, the latter approach provided the highest data rate for the NFT-based systems.…”