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Accelerating LMS-Based Equalization With Correlated Training Sequence in Bandlimited IM/DD Systems

As higher symbol rates are utilized in the intensity modulation and direct detection (IM/DD) scheme to meet the unrelenting growth of data traffic, overcoming the inter-symbol interference (ISI) induced by the limited bandwidth has become increasingly crucial. Channel equalization based on digital signal processing (DSP) is an effective solution, where least-mean squares (LMS) algorithm is adopted to adjust tap coefficients. However, the LMS algorithm usually has slow rate of convergence and requires lots of training symbols. This work proposes a novel training sequence to accelerate the LMS-based equalization. A first-order Markov chain (MC) is employed for sequence generation, which introduces correlation between samples and shapes signal spectrum. Compared with the conventional training sequence that consists of independent and identically distributed (i.i.d.) samples and has a white spectrum, the MC sequence enables faster convergence of tap coefficients and mean-squared error (MSE). Moreover, an experimental demonstration of a 43 Gbaud PAM-4 signal shows that the proposed sequence can achieve a lower pre-forward-error-correction (pre-FEC) bit error rate (BER) than that of the i.i.d. sequence with the same length. When the PAM-4 signal is transmitted over a 5-km standard single mode fiber (SSMF) with 6-dB system bandwidth of 10 GHz, more than 70% training sequence length reduction can be attained. When the fiber length is increased to 10 km and the signal suffers from severe power fading, more than 48% reduction can be achieved.

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Informasi Detail

Judul Seri

JOURNAL OF LIGHTWAVE TECHNOLOGY; Vol.40 No.13 July 1 2022

No. Panggil

-

Penerbit

: .,

Deskripsi Fisik

p. 4268-4275

Bahasa

English

ISBN/ISSN

-

Klasifikasi

NONE

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

-

Subjek

DIGITAL SIGNAL PROCESSING
INTENSITY MODULATION AND DIRECT DETECTION
CHANNEL EQUALIZATION
LEAST-MEAN SQUARES

Info Detail Spesifik

DOI: 10.1109/JLT.2022.3164031

Pernyataan Tanggungjawab

Shuang Yao, Xizi Tang, Rui Zhang, Qi Zhou, Shang-Jen Su, Chin-Wei Hsu, Yahya Alfadhli, Xiaoli Ma, Gee-Kung Chang

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