Geometric Shaping of 2-Dimensional Constellations in the Presence of Laser Phase Noise

Abstract

In this paper, we propose a geometric shaping (GS) strategy to design 8, 16, 32 and 64-ary modulation formats for the optical fibre channel impaired by both additive white Gaussian (AWGN) and phase noise. The constellations were optimised to maximise generalised mutual information (GMI) using a mismatched channel model. The presented formats demonstrate an enhanced signal-to-noise ratio (SNR) tolerance in high phase noise regimes when compared with their quadrature amplitude modulation (QAM) or AWGN-optimised counterparts. By putting the optimisation results in the context of the 400ZR implementation agreement, we show that GS alone can either relax the laser linewidth (LW) or carrier phase estimation (CPE) requirements of 400 Gbit/s transmission links and beyond. Following the GMI validation, the performance of the presented formats was examined in terms of post forward error correction (FEC) bit-error-rate (BER) for a soft decision (SD) extended Hamming code (128, 120), implemented as per the 400ZR implementation agreement. We demonstrate gains of up to 1.2 dB when compared to the 64-ary AWGN shaped formats.

10 pages, journal, R1

Cited by in corpus (6)

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• Geometrically-Shaped Multi-Dimensional Modulation Formats in Coherent Optical Transmission Systems
• End-to-end Learning of a Constellation Shape Robust to Channel Condition Uncertainties
• End-to-end Optimization of Constellation Shaping for Wiener Phase Noise Channels with a Differentiable Blind Phase Search
• On Shaping Gain of Multidimensional Constellation in Linear and Nonlinear Optical Fiber Channel
• End-to-end Learning of a Constellation Shape Robust to Variations in SNR and Laser Linewidth