Network monitoring is essential to collect compre-hensive data on signal quality in optical networks. As deploying large amounts of monitoring equipment results in elevated cost and power consumption, novel low-cost monitoring methods are continuously being investigated. A new technique called Power Profile Monitoring (PPM) has recently gained traction thanks to its ability to monitor an entire lightpath using a single post-processing unit at the lightpath receiver. PPM does not require to deploy an individual monitor for each span, as in the traditional monitoring technique using Optical Time-Domain Reflectometer (OTDR). PPM and OTDR have different monitoring applications, which will be elaborated in our discussion, hence they can be considered either alternative or complementary techniques according to the targeted monitoring capabilities to be implemented in the network. In this work, we aim to quantify the cost and power consumption of PPM (using OTDR as a baseline reference), as this analysis can provide guidelines for the implementation and deployment of PPM. First, we discuss how PPM and OTDR monitors are deployed, and we formally state a new Optimized Monitoring Placement (OMP) problem for PPM. Solving the OMP problem allows to identify the minimum number of PPM monitors that guarantees that all links in the networks are monitored by at least n PPM monitors (note that using n > 1 allows for increased monitoring accuracy). We prove the NP-hardness of the OMP problem and formulate it using an Integer Linear Programming (ILP) model. Finally, we also devise a heuristic algorithm for the OMP problem to scale to larger topologies. Our numerical results, obtained on realistic topologies, suggest that the cost (power) of one PPM module should be lower than 2.6 times and 10.2 times that of one OTDR for nation-wide and continental-wide topology, respectively.

翻译：网络监测对于收集光网络中信号质量的全面数据至关重要。由于部署大量监测设备会导致成本和功耗上升，新型低成本监测方法正持续受到研究。一种称为功率分布监测（PPM）的新技术近期受到关注，因其能够在光路接收端使用单一后处理单元监测整条光路。与使用光时域反射计（OTDR）的传统监测技术不同，PPM无需为每个跨段部署独立监测器。PPM与OTDR具有不同的监测应用场景（我们将在讨论中详述），因此根据网络中需实现的监测目标能力，它们可被视为替代性或互补性技术。本研究旨在量化PPM的成本与功耗（以OTDR作为基准参考），该分析可为PPM的实施与部署提供指导。首先，我们探讨PPM与OTDR监测器的部署方式，并正式提出针对PPM的优化监测布局（OMP）新问题。解决OMP问题可确定保证网络中所有链路至少被n个PPM监测器覆盖的最小监测器数量（注意使用n>1可提升监测精度）。我们证明了OMP问题的NP难特性，并采用整数线性规划（ILP）模型进行形式化描述。最后，我们还为OMP问题设计了启发式算法以适应更大规模的拓扑结构。在真实拓扑上获得的数值结果表明：对于国家级和洲级拓扑，单个PPM模块的成本（功耗）应分别低于单个OTDR的2.6倍和10.2倍。