Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise

Fuente: arXiv
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Main Authors: Alfredsson, Arni F., Agrell, Erik, Karlsson, Magnus, Wymeersch, Henk
Format: Preprint
Published: 2020
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author Alfredsson, Arni F.
Agrell, Erik
Karlsson, Magnus
Wymeersch, Henk
author_facet Alfredsson, Arni F.
Agrell, Erik
Karlsson, Magnus
Wymeersch, Henk
contents The effects of transmitter-side multidimensional signal rotations on the performance of multichannel optical transmission are studied in the presence of laser phase noise. In particular, the laser phase noise is assumed to be uncorrelated between channels. To carry out this study, a simple multichannel laser-phase-noise model that has been experimentally validated for weakly-coupled multicore-fiber transmission is considered. As the considered rotation scheme is intended to work in conjunction with receiver-side carrier phase estimation (CPE), the model is modified to further assume that imperfect CPE has taken place, leaving residual phase noise in the processed signal. Based on this model, two receiver structures are derived and used to numerically optimize transmitter-side signal rotations through Monte Carlo simulations. For reasonable amounts of residual phase noise, rotations based on Hadamard matrices are found to be near-optimal for transmission of four-dimensional signals. Furthermore, Hadamard rotations can be performed for any dimension that is a power of two. By exploiting this property, an increase of up to 0.25 bit per complex symbol in an achievable information rate is observed for transmission of higher-order constellations.
format Preprint
id arxiv_https___arxiv_org_abs_2003_05858
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise
Alfredsson, Arni F.
Agrell, Erik
Karlsson, Magnus
Wymeersch, Henk
Signal Processing
The effects of transmitter-side multidimensional signal rotations on the performance of multichannel optical transmission are studied in the presence of laser phase noise. In particular, the laser phase noise is assumed to be uncorrelated between channels. To carry out this study, a simple multichannel laser-phase-noise model that has been experimentally validated for weakly-coupled multicore-fiber transmission is considered. As the considered rotation scheme is intended to work in conjunction with receiver-side carrier phase estimation (CPE), the model is modified to further assume that imperfect CPE has taken place, leaving residual phase noise in the processed signal. Based on this model, two receiver structures are derived and used to numerically optimize transmitter-side signal rotations through Monte Carlo simulations. For reasonable amounts of residual phase noise, rotations based on Hadamard matrices are found to be near-optimal for transmission of four-dimensional signals. Furthermore, Hadamard rotations can be performed for any dimension that is a power of two. By exploiting this property, an increase of up to 0.25 bit per complex symbol in an achievable information rate is observed for transmission of higher-order constellations.
title Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise
topic Signal Processing
url https://arxiv.org/abs/2003.05858