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Semi-Supervised and Supervised Nonlinear Equalizers in Fiber-FSO Converged System

We leverage the supervised and semi-supervised Volterra nonlinear equalizers (VNLE) to mitigate the system nonlinearity. Two methods are employed to estimate the coefficients: ordinary least square (OLS) estimator and the least absolute shrinkage and selection operator (Lasso). Due to the additional coupling loss and higher propagation loss in bad weather conditions, FSO-fiber link requires a more stringent power budget. Higher modulation depth and transmitter output power can improve the link budget but need to make nonlinearity correction. Thus, we comprehensively perform a proof-of-concept demonstration in a fiber-FSO converged link with pulse amplitude modulation (PAM). Compared with conventional supervised VNLE using OLS, the coefficients estimated from Lasso require a smaller training symbol overhead. In both the 50-Gbaud PAM4 (at the 1.22 × 10 −2 threshold) and 35-Gbaud PAM8 (at the 2 × 10 −2 threshold) cases, when the labeled data proportion is 5%, supervised VNLE using Lasso exhibits a received optical power (ROP) improvement up to 3 dB, compared to supervised VNLE using OLS. Moreover, the semi-supervised method can utilize the unlabeled data and further improve the performance without adding signal overhead to the system. In our 50-Gbaud PAM4 experiment, with 60% unlabeled data, the semi-supervised VNLE based on the soft decision (SD) and Lasso demonstrates up to 3-dB sensitivity gain at the BER threshold of 4.5 × 10 −3 compared with the supervised VNLE using Lasso. The semi-supervised VNLE using SD and Lasso also demonstrates a line rate improvement >100% at the 4.5 × 10 −3 Pre-FEC BER threshold over the conventional supervised VLNE using OLS.

Ketersediaan

Informasi Detail

Judul Seri

JOURNAL OF LIGHTWAVE TECHNOLOGY; Vol.39 No.19 October 1 2021

No. Panggil

-

Penerbit

: .,

Deskripsi Fisik

p. 6175-6181

Bahasa

English

ISBN/ISSN

-

Klasifikasi

NONE

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

-

Subjek

FREE SPACE OPTICS
FIBER OPTICAL COMMUNICATION
FIBER-WIRELESS INTERGRATION
LASSO NONLINEARITY CORRECTION

Info Detail Spesifik

DOI: 10.1109/JLT.2021.3098337

Pernyataan Tanggungjawab

Rui Zhang, Xizi Tang, Chin-Wei Hsu, You-Wei Chen, Gee-Kung Chang

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