Multilevel Coding with Flexible Probabilistic Shaping for Rate-Adaptive and Low-Power Optical Communications

Abstract

A novel multilevel coded modulation scheme with probabilistic shaping is presented. It can reduce the power consumption up to 9 times compared with uniform signaling in the regime of typical hard-decision FEC thresholds.

On the Performance under Hard and Soft Bitwise Mismatched-Decoding

“…SNR lim is 10.9 dB, 13.9 dB, 16.3 dB, 19.0 dB, 13.0 dB, and 13.4 dB for 16, 32, 64, 128-QAM, BICM PS-64-QAM, and MLC PS-64-QAM, resp. In this MLC, soft FEC protects the least significant bits only, the parity bits are placed only on the sign bit, and multistage decoding is performed [10]. Under SNR aux = SNR tr (solid line) and SNR aux = SNR lim (dotted line), the relative SNR is defined as SNR tr /SNR lim .…”

Required and Received SNRs in Coded Modulation

“…Probabilistic amplitude shaping [4] was also considered, namely PS- 16 denote entropy and 1-D symbol, respectively. Both BICM and MLC [8] were studied. The considered MLC treats only 1-D pulse amplitude modulation symbols.…”

“…Coded modulation [1][2][3][4][5][6][7][8] is one of the key technologies in optical fiber communication to realize better tradeoffs between performance and complexity. Forward error correction (FEC) efficiently eliminates bit errors, multilevel modulation controls spectral efficiency, and constellation shaping reduces the gap between the Shannon capacity and achievable rates for pragmatic modulation formats with uniformly distributed symbol probabilities.…”

“…This characterization is useful for modelling the performance of coded modulation transceivers. We also compare the required optical SNR (ROSNR) and transceiver SNR assuming bitinterleaved coded modulation (BICM) [3] or multilevel coding (MLC) [8] to find a good solution for deployable systems.…”

Sparse-Dense MLC for Peak Power Constrained Channels

“…Here multilevel coding (MLC) [12,13] can achieve better performance tradeoff by reducing the throughput of SD-FEC. There is room for further improvement of the MLC scheme [13] to coexist with constellation shaping for low SEs or peak power constrained channels.…”