List-Encoding CCDM: A Nonlinearity-Tolerant Shaper Aided by Energy Dispersion Index

• DOI: 10.1109/jlt.2021.3125783
• Publication Date: 2021-11-08T22:42:43Z
• Authors: Kaiquan Wu; Gabriele Liga; Alireza Sheikh; Yunus Can Gultekin; Frans M. J. Willems; Alex Alvarado
• Keywords: Signal Processing (eess.SP); fiber nonlinearities; probabilistic amplitude shaping; FOS: Electrical engineering, electronic engineering, information engineering; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; Electrical Engineering and Systems Science - Signal Processing; Constant-composition distribution matching

Recently, a metric called energy dispersion index (EDI) was proposed to indicate the nonlinear interference (NLI) induced by correlated symbols during optical transmission. In this paper, we propose a new shaper architecture to decrease the EDI of transmitted symbols and thus, increase the signal-to-noise ratio (SNR). We call this shaper the list-encoding constant-composition distribution matcher (L-CCDM). L-CCDM consists of an additional EDI selecting module, which is compatible with standard probabilistic amplitude shaping (PAS) architecture. Numerical results obtained from a multi-span multi-channel system show that when compared to standard CCDM with 256-ary quadrature amplitude modulation (256QAM), the proposed architecture offers an effective SNR gain of 0.35 dB, an achievable information rate gain of 0.22 bit/4D-symbol, or equivalently an 8% reach extension.