Hu Sheng, Zheng Tianqi, Bian Chengzhen, Yang Xiongwei, Sun Xinda, Zhu Zonghui, Gou Yumeng, Meng Yuanxiao, Zhang Jie, Ge Jingtao, Li Yichen, Wang Kaihui
State Key Laboratory of Integrated Chips and Systems, Fudan University, Shanghai 200433, China.
Sensors (Basel). 2024 Dec 9;24(23):7872. doi: 10.3390/s24237872.
In this work, we implemented a short-reach real-time optical communication system using MLP for pre-distortion. Lookup table (LUT) algorithms are commonly employed for pre-distortion in intensity modulation and direct detection (IM/DD) systems. However, storage limitations typically restrict the LUT pattern length to 9, limiting its effectiveness in compensating for nonlinear effects. A multilayer perceptron (MLP) can overcome this limitation by predicting errors and generating pre-distorted signals, thus replacing the extensive storage requirements of LUTs with minimal computational resources. The MLP-based digital pre-distortion (MLP-DPD) technique enables the creation of long-pattern LUTs for improved nonlinear compensation. In this work, an MLP-DPD scheme was implemented on a field-programmable gate array (FPGA). The FPGA was used to generate a 14.7456 GBaud pre-distorted pulse amplitude modulation 4-level (PAM4) signal. This signal was then transmitted over 20 km of standard single-mode fiber (SSMF). At the receiver, the parallel constant modulus algorithm (PCMA) was applied for signal processing. The bit error rate (BER) achieved met the 2.4 × 10 threshold for soft-decision forward error correction (SD-FEC), enabling a net transmission bit rate of 24.576 Gbit/s. This approach demonstrates the feasibility of using MLP-DPD for effective nonlinear compensation in high-speed optical communication systems with limited resources.
在这项工作中，我们实现了一种使用多层感知器（MLP）进行预失真的短距离实时光通信系统。查找表（LUT）算法通常用于强度调制和直接检测（IM/DD）系统中的预失真。然而，存储限制通常将LUT模式长度限制为9，这限制了其在补偿非线性效应方面的有效性。多层感知器（MLP）可以通过预测误差和生成预失真信号来克服这一限制，从而用最少的计算资源取代LUT大量的存储需求。基于MLP的数字预失真（MLP-DPD）技术能够创建长模式LUT以改善非线性补偿。在这项工作中，一种MLP-DPD方案在现场可编程门阵列（FPGA）上得以实现。该FPGA用于生成一个14.7456 GBaud的预失真4电平脉冲幅度调制（PAM4）信号。然后该信号通过20 km的标准单模光纤（SSMF）进行传输。在接收器端，并行恒模算法（PCMA）被应用于信号处理。实现的误码率（BER）满足软判决前向纠错（SD-FEC）的2.4×10阈值，实现了24.576 Gbit/s的净传输比特率。这种方法证明了在资源有限的高速光通信系统中使用MLP-DPD进行有效非线性补偿的可行性。
