Spectrum fragmentation has always been a major issue to overcome toward spectrally efficient Flex-Grid over Single-Mode Fiber dynamic optical networks and continues like so when evolving to Flex-Grid over Spatial Division Multiplexing (SDM). A possible strategy to eliminate its pernicious effects is to divide the available spectrum into several partitions, dedicating each one of them to only support connections with identical spectral requirements. In this way, a first-fit spectrum assignment ensures that spectral gaps at each spectral partition will always match the bandwidth needs of future connection requests. In this paper, we extend this strategy to be applicable to Flex-Grid/SDM dynamic optical networks. Furthermore, leveraging the spatial multiplicity offered by SDM, we also investigate spatial partitioning as an effective yet simpler and more easily manageable solution to also eliminate the spectrum fragmentation negative effects. Both strategies are numerically evaluated in two reference Flex-Grid/SDM backbone networks with × 7 spatial multiplicity, yielding noteworthy carried network load gains up to 18% versus a non-partitioned network scenario. When increasing the spatial multiplicities up to × 30, such gains tend to stabilize around 3–4%. Some results are also obtained under unexpected traffic profile deviations, showing that, even under moderate deviations, partitioning becomes beneficial. Comparing spectral and spatial partitioning, they tend to perform quite similar in all cases. This makes us advocate for spatial partitioning as a more interesting solution for spectrum fragmentation avoidance in this kind of networks.

中文翻译：

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在Flex-grid / SDM动态光核心网络中，空间划分可避免主动频谱碎片化

频谱碎片化一直是克服单模光纤动态光网络上频谱效率高的Flex-Grid的主要问题，并且在发展为空分复用（SDM）的Flex-Grid时一直如此。消除其有害影响的一种可能策略是将可用频谱分成几个分区，每个分区专用于仅支持具有相同频谱要求的连接。这样，首次拟合频谱分配可确保每个频谱分区上的频谱间隙将始终匹配未来连接请求的带宽需求。在本文中，我们将这种策略扩展到适用于Flex-Grid / SDM动态光网络。此外，利用SDM提供的空间多样性，我们还将空间划分作为一种有效而又简单且易于管理的解决方案，以消除频谱碎片化的负面影响。两种策略均在具有×7空间多样性的两个参考Flex-Grid / SDM骨干网中进行了数值评估，与未分区的网络方案相比，可带来高达18％的显着承载网络负载。将空间多重性提高到×30时，此类增益趋于稳定在3-4％左右。在意外的流量分布偏差下也可以获得一些结果，表明即使在中等偏差下，分区也变得有益。比较频谱和空间划分，它们在所有情况下的表现都非常相似。