A Study on Multifiber WDM Network Architecture

在我们的研究中，我们考虑了一种城域核心环的设计原则，其中业务量远远超过单根WDM光纤的容量，因此需要多根光纤。有些人可能会在每个核心节点中使用多个WDM光纤和超大容量路由器，尽管他们知道原始设计非常昂贵，因为每个节点都需要进行OEO转换和膨胀的路由器容量。一些高级人员会更喜欢将多个WDM环网堆叠在一起。然而，他们也发现，每个节点都需要许多OADM。因此，我们看到，没有一个传统的设计原则能够为大容量的城域WDM核心网提供经济有效的解决方案。我们相信，作者提出的多光纤WDM网络(MWN)提供了一个新的机会。然而，与这两种设计相比，MWN需要更多的光纤，而MWN需要简单且经济的OADM。在我们的研究中，我们首次提出了双向多光纤WDM网络的基本设计概念。我们证明了双向传输技术可以将多光纤WDM环网所需的光纤数量减半。与传统的双向技术不同，我们的设计不使用WDM交织器。相反，我们在一根光纤上使用了两组相同的相反方向的波长，这提供了可能的最佳性能，但长期以来一直被认为是不切实际的。我们从理论上分析了瑞利后向散射噪声的影响。数值分析表明，采用简单的边缘滤波后，瑞利后向散射引起的光功率损失可以降低到1分贝以下。我们还研究了一些先进的设计方案。我们认为，以前没有使用两组相同波长的可行双向设计。最后，我们想强调的是，这些结果使得多光纤WDM网络对于大容量的城域WDM网络更具吸引力

In our study, we consider a design principle of metro core ring, where traffic volume far exceeds the capacity of a single WDM fiber, and thus multiple fibers are required. Some people may use multiple WDM fibers and ultra high-capacity routers in every core node, although they know the primitive design is very expensive due to OEO conversion and inflated router capacity needed at every node. Some advanced people will prefer multiple WDM ring networks in a stack. However, they also find that many OADMs are necessary in every node. As a consequence, we see that no conventional design principle gives a cost-effective solution for high-capacity metro WDM core networks.We believe that the multifiber WDM networks (MWN), which has been proposed by the authors, offer a new opportunity. However, MWNs require a more number of fibers than that of those two designs, while MWNs need simple and economic OADMs. In our study, we developed a basic design concept of the bidirectional multifiber WDM networks for the first time. We showed that bidirectional transmission techniques can halve the number of fibers necessary for multifiber WDM ring networks. Our design uses no WDM interleaver unlike conventional bidirectional techniques. Instead, we used two identical sets of wavelengths for opposite directions on a single fiber, which gives the best possible performance, but has long been believed to be impractical.We theoretically analyzed the effect of Rayleigh back scattering noise. Our numerical analysis showed that optical power penalty due to Rayleigh backscattering can be reduced less than 1 dB with simple edge filters. We also investigated some advanced design alternatives. We believe that there is no feasible bidirectional design using two identical sets of wavelengths ever before. Finally, we'd like to stress that the results make multifiber WDM networks more attractive for high-capacity WDM networks for metro areas