Current optical coherent transponders technology is driving data rates towards 1 Tb/s/ $\lambda $ and beyond. This trend requires both high-performance coded modulation schemes and efficient implementation of the forward-error-correction (FEC) decoder. A possible solution to this problem is combining advanced multidimensional modulation formats with low-complexity hybrid HD/SD FEC decoders. Following this rationale, in this letter we combine two recently introduced coded modulation techniques: the geometrically-shaped 4D-64 polarization ring-switched and the soft-aided bit-marking-scaled reliability decoder. This joint scheme enabled us to experimentally demonstrate the transmission of $11\times 218$ Gbit/s channels over transatlantic distances at 5.2 bit/4D-sym. Furthermore, a 30% reach increase is demonstrated over PM-8QAM and conventional HD-FEC decoding for product codes.

中文翻译：

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通过低复杂度混合 HD/SD FEC 和改进的 4D 调制将覆盖范围增加 30%

当前的光相干转发器技术正在将数据速率推向 1 Tb/s/ $\lambda $ 超越。这种趋势需要高性能编码调制方案和前向纠错 (FEC) 解码器的有效实现。此问题的一个可能解决方案是将高级多维调制格式与低复杂度相结合杂交种HD/SD FEC 解码器。遵循这一基本原理，在这封信中，我们结合了两种最近引入的编码调制技术：几何形状的 4D-64 偏振环切换和软辅助位标记缩放可靠性解码器。这种联合方案使我们能够通过实验证明 $11\乘以 218$ 以 5.2 位/4D-sym 跨越跨大西洋距离的 Gbit/s 信道。此外，与 PM-8QAM 和传统 HD-FEC 解码产品代码相比，范围增加了 30%。