Hard-Decision Coded Modulation for High-Throughput Short-Reach Optical Interconnect.

Bin Chen,Yi Lei,Chigo Okonkwo,Gabriele Liga,Alex Alvarado

doi:10.3390/e22040400

Bin Chen, Yi Lei + Show 3 more

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https://doi.org/10.3390/e22040400

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Abstract

Coded modulation (CM), a combination of forward error correction (FEC) and high order modulation formats, has become a key part of modern optical communication systems. Designing CM schemes with strict complexity requirements for optical communications (e.g., data center interconnects) is still challenging mainly because of the expected low latency, low overhead, and the stringent high data rate requirements. In this paper, we propose a CM scheme with bit-wise hard-decision FEC and geometric shaping. In particular, we propose to combine the recently introduced soft-aided bit-marking decoding algorithm for staircase codes (SCCs) with geometrically-shaped constellations. The main goal of this CM scheme is to jointly boost the coding gain and provide shaping gain, while keeping the complexity low. When compared to existing CM systems based on M-ary quadrature-amplitude modulation (MQAM, ) and conventional decoding of SCCs, the proposed scheme shows improvements of up to dB at a bit-error rate of in the additive white Gaussian noise channel. For a nonlinear optical fiber system, simulation results show up to reach increase. In addition, the proposed CM scheme enables rate adaptivity in single-wavelength systems, offering six different data rates between 450 Gbit/s and 666 Gbit/s.

Highlights

Modern optical fiber communication systems have been revolutionized by digital coherent technology via techniques such as pulse shaping, digital signal processing (DSP), and forward error correction (FEC) [1].In order to support the Internet’s exponential traffic growth and improve the transmission reach, the most natural way of achieving this goal is using high spectral efficiency (SE) modulation formats and powerfulFEC techniques
Results after propagation over single-span standard single-mode fiber (SSMF) are shown in Figure 7 as Achievable Information Rates (AIRs) vs. launch power per wavelength-division multiplexing (WDM) channel (Pch )
In order to evaluate the reach increase for the proposed coded modulation (CM) for single-span transmission, we implemented staircase codes (SCCs) for the central WDM channel at the optimum launch power, which is obtained from Figure 7

Summary

Introduction

Modern optical fiber communication systems have been revolutionized by digital coherent technology via techniques such as pulse shaping, digital signal processing (DSP), and forward error correction (FEC) [1].In order to support the Internet’s exponential traffic growth and improve the transmission reach, the most natural way of achieving this goal is using high spectral efficiency (SE) modulation formats and powerfulFEC techniques. In order to support the Internet’s exponential traffic growth and improve the transmission reach, the most natural way of achieving this goal is using high spectral efficiency (SE) modulation formats and powerful. The purpose of CM is to increase the number of information bits per channel use (or information rate). High-order modulation formats can boost the information rates; there is often a gap between the Entropy 2020, 22, 400; doi:10.3390/e22040400 www.mdpi.com/journal/entropy. Entropy 2020, 22, 400 performance of a practical CM scheme and the corresponding theoretical limit. The gap is due to the use of uniform signaling with equidistant signal constellation points and the suboptimality of pragmatic FEC schemes. In order to enhance the performance of CM systems and reduce the two losses above, advanced

Results

Discussion

Conclusion