Li Peixuan, Pan Wei, Zou Xihua, Yan Lianshan, Luo Bin, Chen You-Wei, Chang Gee-Kung
Opt Lett. 2019 Aug 1;44(15):3901-3904. doi: 10.1364/OL.44.003901.
We propose and experimentally demonstrate a novel digital post-linearization algorithm for the mobile fronthaul system employing bandwidth-efficient multiple intermediate frequency-over-fiber technology and a low-cost directly-modulated laser (DML). The proposed linearization algorithm is distinguished for blind adaption, the absence of training signal, or prior knowledge of the transmission channel. Particularly, it provides a closed-form solution for the estimation of optimal linearizer coefficients, leading to a non-iterative mode without convergence restrictions. In our experiments, one and nine 200 MHz 64-QAM OFDM IF signals (or channels) are transmitted over a 10 km single-mode fiber link using a DML. In both cases (one and nine IF channels), the linearization performance of the proposed algorithm is experimentally validated in terms of the reduction (>8 dB) of the adjacent channel leakage ratio, decrease (>10 dB) of error vector magnitude (EVM), and an increase (>9 dB) of EVM-compliant input RF power range.
我们提出并通过实验证明了一种新颖的数字后线性化算法，该算法用于采用带宽高效的多中频光纤技术和低成本直接调制激光器（DML）的移动前传系统。所提出的线性化算法的特点是具有盲自适应能力，无需训练信号或传输信道的先验知识。特别地，它为最优线性化器系数的估计提供了一个闭式解，从而实现了无收敛限制的非迭代模式。在我们的实验中，使用一个DML在10 km单模光纤链路上传输了一个和九个200 MHz 64-QAM OFDM中频信号（或信道）。在这两种情况（一个和九个中频信道）下，所提算法的线性化性能通过相邻信道泄漏比降低（>8 dB）、误差矢量幅度（EVM）减小（>10 dB）以及符合EVM的输入射频功率范围增加（>9 dB）在实验上得到了验证。
