Recent advances in physical layer optics have made slicing of optical bands into multiple subbands with different bandwidths possible. Due to this development, spectrum allocation has become easier in elastic optical networks (EONs). More specifically, owing to the slicing technology, the defragmentation problem in EONs can be addressed easily, i.e., more demands can be fit into empty spectrum slots by breaking the demands as needed using the slicing technology. This paper proposes a spectrum allocation scheme considering the slicing process at any nodes, e.g., source node and intermediate nodes, in EONs. Slicing-and-stitching technology is applied to break the contiguous-spectrum constraint in an EON so that spectrum fragmentation is reduced. While slicing a demand from one node to another, the following questions must be answered: (1) Which parts of the spectrum band should be sliced? (2) In which node(s) along the path of a demand should the slicings be done to reduce the bandwidth blocking rate? To answer the above questions, we formulate a mixed-integer linear programming (MILP) model that jointly addresses the above questions as well as minimizes the total number of slicers in a network. To measure the performance of the MILP, we used the bandwidth blocking ratio (BBR) of the network as a performance metric. Our results from the MILP show that introducing slicing at every node in the network improves the BBR by as much as 68% compared to a conventional case where slicing a demand is allowed only at the source node.

中文翻译：

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弹性光网络中考虑频谱切片的频谱分配方案

物理层光学的最新进展使得将光带分割成具有不同带宽的多个子带成为可能。由于这一发展，弹性光网络 (EON) 中的频谱分配变得更加容易。更具体地说，由于采用了切片技术，可以轻松解决EON中的碎片整理问题，即通过使用切片技术按需拆分需求，可以将更多的需求放入空的频谱槽中。本文提出了一种频谱分配方案，该方案考虑了EON 中任何节点（例如源节点和中间节点）的切片过程。应用Slicing-and-stitching技术打破EON中连续频谱约束，减少频谱碎片。在将需求从一个节点切片到另一个节点时，必须回答以下问题：(1) 应该对频段的哪些部分进行切片？(2) 应该在需求路径上的哪些节点进行切片以降低带宽阻塞率？为了回答上述问题，我们制定了一个混合整数线性规划 (MILP) 模型，该模型共同解决了上述问题，并最大限度地减少了网络中的切片器总数。为了衡量 MILP 的性能，我们使用网络的带宽阻塞率 (BBR) 作为性能指标。我们来自 MILP 的结果表明，与仅在源节点允许对需求进行切片的传统情况相比，在网络中的每个节点引入切片可将 BBR 提高多达 68%。