Opt Lett. 2018 Oct 15;43(20):5130-5133. doi: 10.1364/OL.43.005130.
A spectrally efficient digital mobile fronthaul (MFH) with discrete cosine transform and multi-band quantization (DCT-MBQ) is first proposed and experimentally demonstrated. In this approach, the baseband orthogonal frequency division multiplexing (OFDM) symbols are segmented into individual blocks and independently transformed by DCT to obtain a set of transform coefficients. Different from digitizing each OFDM sample with the same number of quantization bits (QBs) in previous digital MFH, MBQ is introduced to separately digitize different parts of the coefficients with different numbers of QBs according to the significance of these coefficients. Furthermore, the part of transform coefficients with little significance is discarded. Thus, the total number of required QBs for digitizing an OFDM symbol can be greatly reduced and, thereby, high bandwidth efficiency can be achieved. In the experiment, the proposed DCT-MBQ-based digital MFH transmission is demonstrated over a 25 Gb/s four-level pulse amplitude modulation intensity modulation-direct detection optical link supporting up to 16×100 MHz 5G new radio carriers with 1024 QAM, achieving an error vector magnitude of 0.65%. The equivalent common public radio interface rates from 55 to 158 Gb/s are supported.
本文首次提出并实验验证了一种具有离散余弦变换和多带量化（DCT-MBQ）的谱效数字移动前传（MFH）。在该方法中，基带正交频分复用（OFDM）符号被分成单独的块，并通过 DCT 进行独立变换，以获得一组变换系数。与以前的数字 MFH 中对每个 OFDM 样点使用相同数量的量化位（QBs）进行数字化不同，MBQ 被引入，根据这些系数的重要性，分别用不同数量的 QBs 对系数的不同部分进行数字化。此外，还丢弃了意义不大的变换系数部分。因此，用于数字化一个 OFDM 符号的所需 QB 的总数可以大大减少，从而实现了高带宽效率。在实验中，演示了基于所提出的 DCT-MBQ 的数字 MFH 传输，该传输在支持多达 16×100MHz 5G 新无线电载波和 1024QAM 的 25Gb/s 四电平脉冲幅度调制强度调制直接检测光链路中进行，实现了 0.65%的误差向量幅度。支持从 55 到 158Gb/s 的等效公共无线电接口速率。
