Opt Lett. 2023 Feb 15;48(4):1076-1079. doi: 10.1364/OL.482246.
We propose and experimentally demonstrate a radio-frequency digital resolution enhancer (RF-DRE) to mitigate the quantization noise of the RF signal induced by the low-resolution digital-to-analog converter (DAC) in the virtual-carrier-assisted millimeter-wave (mm-wave) signal transmission system. By introducing a bandpass filter (BPF) as the reference for the RF-DRE algorithm, we can design the quantization noise and shape its spectrum inversely to the bandpass filter. By these means, the quantization noise in the target RF frequency range can be effectively mitigated. In the simulation, the bit error rate (BER) of a 4-bit DAC-quantized 16 Gb/s 256QAM signal at 30 GHz is improved from 3.36e-2 to 7.43e-3 by using the RF-DRE. In our experiment, 30 GHz virtual-carrier-assisted mm-wave transmission of 12 Gb/s 64QAM signals over 25 km of standard signal mode fiber (SSMF) is realized. By using the RF-DRE, the BER of a 4-bit DAC-quantized signal can be improved from 6.88e-3 to 1.49e-3, and a 5-bit DAC exhibits a similar performance to an 8-bit DAC without the RF-DRE. Therefore, low-resolution and low-cost DACs can be used for mm-wave signal generation with the help of the proposed RF-DRE.
我们提出并实验验证了一种射频数字分辨率增强器（RF-DRE），以减轻虚拟载波辅助毫米波（mmWave）信号传输系统中低分辨率数模转换器（DAC）对 RF 信号引入的量化噪声。通过引入带通滤波器（BPF）作为 RF-DRE 算法的参考，我们可以设计量化噪声并使其频谱反型于带通滤波器。通过这些方法，可以有效地减轻目标 RF 频率范围内的量化噪声。在仿真中，通过使用 RF-DRE，将 30GHz 处 4 位 DAC 量化的 16Gbps 256QAM 信号的误码率（BER）从 3.36e-2 提高到 7.43e-3。在实验中，实现了 25km 标准信号模式光纤（SSMF）上 30GHz 虚拟载波辅助 mmWave 传输的 12Gbps 64QAM 信号。通过使用 RF-DRE，4 位 DAC 量化信号的 BER 可以从 6.88e-3 提高到 1.49e-3，而 5 位 DAC 在没有 RF-DRE 的情况下表现出与 8 位 DAC 类似的性能。因此，在 RF-DRE 的帮助下，可以使用低分辨率和低成本的 DAC 来生成 mmWave 信号。
