Spatial-division multiplexing (SDM) and band-division multiplexing (BDM) have emerged as solutions to expand the capacity of existing C-band wavelength-division multiplexing (WDM) optical systems and to deal with increasing traffic demands. An important difference between these two approaches is that BDM solutions enable data transmission over unused spectral bands of already-deployed optical fibers, whereas SDM solutions require the availability of additional fibers to replicate C-band WDM transmission. On the other hand, to properly design a multiband optical line system (OLS), the following fiber propagation effects have been taken into account in the analysis: (i) stimulated Raman scattering (SRS), which induces considerable power transfer among bands; (ii) frequency dependence of fiber parameters such as attenuation, dispersion, and nonlinear coefficients; and (iii) utilization of optical amplifiers with different doping materials, thus leading to different characteristics, e.g., in terms of noise figures. This work follows a two-step approach: First, we aim at maximizing and flattening the quality of transmission (QoT) when adding L- and ${\rm L} {+} {\rm S}$-bands to a traditional WDM OLS where only the C-band is deployed. This is achieved by applying a multiband optimized optical power control for BDM upgrades, which consists of setting a pre-tilt and power offset in the line amplifiers, thus achieving a considerable increase in QoT, both in average value and flatness. Second, the SDM approach is used as a benchmark for the BDM approach by assessing network performance on three network topologies with different geographical footprints. We show that, with optical power properly optimized, BDM may enable an increase in network traffic, slightly less than an SDM upgrade but still comparable, without requiring additional fiber cables.

中文翻译：

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C + L + S多频带光传输的功率控制策略和网络性能评估

作为扩展现有C波段波分复用（WDM）光学系统容量并解决日益增长的流量需求的解决方案，空分复用（SDM）和带分复用（BDM）已经出现。这两种方法之间的重要区别在于，BDM解决方案能够在已部署的光纤的未使用频谱带上进行数据传输，而SDM解决方案则需要额外的光纤来复制C波段WDM传输。另一方面，为了适当地设计多频带光线路系统（OLS），在分析中考虑了以下光纤传播效应：（i）受激拉曼散射（SRS），在频带之间引起相当大的功率传输；（ii）光纤参数的频率依赖性，例如衰减，色散，和非线性系数；（iii）利用具有不同掺杂材料的光放大器，从而导致不同的特性，例如在噪声系数方面。这项工作分两步进行：首先，我们的目标是在向传统WDM添加L频段和$ {\ rm L} {+} {\ rm S} $频段时，最大化并扁平化传输质量（QoT）仅部署C波段的OLS。这是通过为BDM升级应用多频带优化的光功率控制来实现的，该控制包括在线路放大器中设置预倾斜和功率偏移，从而在平均值和平坦度方面实现QoT的大幅提高。其次，通过评估具有不同地理足迹的三种网络拓扑上的网络性能，将SDM方法用作BDM方法的基准。我们证明