We experimentally demonstrated a low-complexity probabilistic shaping (PS) 16-ary quadrature amplitude modulation (16QAM) scheme based on intra-symbol bit-weighted distribution matching (Intra-SBWDM) for discrete multi-tone (DMT) symbols with field-programmable gate array implementation in an intensity modulation and direct detection (IM-DD) system. Different from the traditional PS scheme such as Gallager many-to-one mapping, hierarchical distribution matching and constant composition distribution matching, the Intra-SBWDM scheme with lower computation and hardware complexity does not need to continuously refine the interval to find the target symbol probability, nor does it need a look-up table, so it does not introduce a large number of extra redundant bits. In our experiment, four PS parameter values (k = 4, 5, 6, and 7) are investigated in a real-time short-reach IM-DD system. 31.87-Gbit/s net bit PS-16QAM-DMT (k = 4) signal transmission is achieved. The results show that the receiver sensitivity in terms of the received optical power of the real-time PS scheme based on Intra-SBWDM (k = 4) over OBTB/20 km standard single-mode fiber can be improved by about 1.8/2.2 dB at the bit error rate (BER) of 3.8 × 10⁻³, compared to the uniformly-distributed DMT. In addition, the BER is steadily lower than 3.8 × 10⁻³ during a one-hour measurement for PS-DMT transmission system.

中文翻译：

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IM-DD 系统中 16QAM-DMT 信号的低复杂度 PS 方案的实时演示

我们通过实验证明了一种基于符号内比特加权分布匹配 (Intra-SBWDM) 的低复杂度概率整形 (PS) 16 元正交幅度调制 (16QAM) 方案，用于具有现场可编程的离散多音 (DMT) 符号强度调制和直接检测 (IM-DD) 系统中的门阵列实现。不同于传统的Gallager多对一映射、分层分布匹配、常量分布匹配等PS方案，Intra-SBWDM方案计算量和硬件复杂度较低，不需要不断细化区间来寻找目标符号概率，也不需要查找表，所以不会引入大量额外的冗余位。在我们的实验中，四个 PS 参数值 ( k= 4、5、6 和 7) 在实时短距离 IM-DD 系统中进行了研究。实现了31.87-Gbit/s 净比特 PS-16QAM-DMT ( k = 4) 信号传输。结果表明，基于Intra-SBWDM（ k =4）的实时PS方案在OBTB/20km标准单模光纤上的接收光功率接收灵敏度可提高约1.8/2.2dB与均匀分布的 DMT 相比，误码率 (BER) 为 3.8 × 10 ^{-3 。}此外，在 PS-DMT 传输系统的一小时测量期间， BER 稳定低于 3.8 × 10 ^{-3 。}