Huffman-Coded Sphere Shaping for Extended Reach Single-Span Links

Pavel Skvortcov, Ian David Phillips, Wladek Forysiak, Toshiaki Koike-akino, Keisuke Kojima, Kieran Parsons, David Millar

Research output: Contribution to journalArticlepeer-review

Abstract

Huffman-coded sphere shaping (HCSS) is an algorithm for finite-length probabilistic constellation shaping, which provides nearly optimal energy efficiency at low implementation complexity. In this paper, we experimentally study the nonlinear performance of HCSS employing dual-polarization 64-ary quadrature amplitude modulation (DP-64QAM) in an extended-reach single-span link comprising 200 km of standard single-mode fiber (SSMF). We investigate the effects of shaping sequence length, dimensionality of symbol mapping, and shaping rate. We determine that the naïve approach of Maxwell-Boltzmann distribution matching-which is optimal in the additive white Gaussian noise channel-provides a maximum achievable information rate (AIR) gain of 0.18 bits/4D-symbol with respect to uniform signaling at optimum launch power in the infinite length regime. Conversely, HCSS can achieve a gain of 0.37 bits/4D-symbol over uniform signaling using amplitude sequence length of 32, which may be implemented without multiplications, using integer comparison and addition operations only. Coded system performance, with a net data rate of approximately 425 Gb/s for both shaped and uniform inputs, is also analyzed.

Original languageEnglish
Article number9340268
JournalIEEE Journal of Selected Topics in Quantum Electronics
Volume27
Issue number3
Early online date29 Jan 2021
DOIs
Publication statusE-pub ahead of print - 29 Jan 2021

Bibliographical note

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Funding: The experimental work carried out at Aston University was
supported by UK EPSRC grant EP/M009092/1. We thank
Lumentum UK for loan of the CFP2-ACO and studentship
support of Pavel Skvortcov, and Socionext for loan of the
DAC/ADC DKs used in this work.

Keywords

  • Adaptive optics
  • Lattices
  • Nonlinear optics
  • Optical fiber communication
  • Optical polarization
  • Optical pulse shaping
  • Optical transmitters
  • Probabilistic logic
  • nonlinear fiber channel
  • probabilistic shaping
  • single-span links
  • sphere shaping

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