Filterless optical networks (FONs) are a cost-effective optical networking technology that replaces reconfigurable optical add-drop multiplexers, used in conventional, wavelength-switched optical networks (WSONs), by passive optical splitters and couplers. FONs follow the drop-and-waste transmission scheme, i.e., broadcast signals without filtering, which generates spectrum waste. Programmable filterless optical networks (PFONs) reduce this waste by equipping network nodes with programmable optical white box switches that support arbitrary interconnections of passive elements. Cost-efficient PFON solutions require optimal routing, modulation format and spectrum assignment (RMSA) to connection requests, as well as optimal design of the node architecture. This paper presents an optimization framework for PFONs. We formulate the RMSA problem in PFONs as a single-step integer linear program (ILP) that jointly minimizes the total spectrum and optical component usage. As RMSA is an NP-complete problem, we propose a two-step ILP formulation that addresses the RMSA sub-problems separately and seeks sub-optimal solutions to larger problem instances in acceptable time. Simulation results indicate a beneficial trade-off between component usage and spectrum consumption in proposed PFON solutions. They use up to 64% less spectrum than FONs, up to 84% fewer active switching elements than WSONs, and up to 81% fewer optical amplifiers at network nodes than FONs or WSONs.

中文翻译：

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可编程无滤波器光网络：架构、设计和资源分配

无滤波器光网络 (FON) 是一种经济高效的光网络技术，用无源光分路器和耦合器取代了传统波长交换光网络 (WSON) 中使用的可重新配置的光分插复用器。 FON遵循丢弃和浪费的传输方案，即未经过滤就广播信号，这会产生频谱浪费。可编程无滤波器光网络 (PFON) 通过为网络节点配备支持无源元件任意互连的可编程光学白盒交换机来减少这种浪费。经济高效的 PFON 解决方案需要针对连接请求进行优化路由、调制格式和频谱分配 (RMSA)，以及节点架构的优化设计。本文提出了 PFON 的优化框架。我们将 PFON 中的 RMSA 问题表述为单步整数线性程序 (ILP)，该程序共同最小化总光谱和光学组件的使用。由于 RMSA 是一个 NP 完全问题，因此我们提出了一个两步 ILP 公式，该公式单独解决 RMSA 子问题，并在可接受的时间内寻求较大问题实例的次优解决方案。仿真结果表明，所提出的 PFON 解决方案在组件使用和频谱消耗之间进行了有益的权衡。它们使用的频谱比 FON 少多达 64%，比 WSON 少多达 84% 的有源开关元件，并且比 FON 或 WSON 网络节点上的光放大器少多达 81%。