[论文解读] Toward Standardized Performance Evaluation of Flow-guided Nanoscale Localization

Arnau Brosa López, Filip Lemić+10 more|arXiv (Cornell University)|Mar 14, 2023

Molecular Communication and Nanonetworks被引用 4

一句话总结

本文提出了一种基于太赫兹通信的血流中流动引导纳米级定位的标准化性能评估框架。开源仿真器模拟了纳米设备的移动性、太赫兹通信、能量采集以及基于脉冲的调制，生成客观基准，揭示当前解决方案的区域检测准确率最高仅为40%，主要由于通信不可靠和间歇性运行。

ABSTRACT

Nanoscale devices with Terahertz (THz) communication capabilities are envisioned to be deployed within human bloodstreams. Such devices will enable fine-grained sensing-based applications for detecting early indications (i.e., biomarkers) of various health conditions, as well as actuation-based ones such as targeted drug delivery. Associating the locations of such events with the events themselves would provide an additional utility for precision diagnostics and treatment. This vision yielded a new class of in-body localization coined under the term "flow-guided nanoscale localization". Such localization can be piggybacked on THz communication for detecting body regions in which biological events were observed based on the duration of one circulation of a nanodevice in the bloodstream. From a decades-long research on objective benchmarking of "traditional" indoor localization, as well as its eventual standardization (e.g., ISO/IEC 18305:2016), we know that in early stages the reported performance results were often incomplete (e.g., targeting a subset of relevant performance metrics), carrying out benchmarking experiments in different evaluation environments and scenarios, and utilizing inconsistent performance indicators. To avoid such a "lock-in" in flow-guided localization, in this paper we propose a workflow for standardized performance evaluation of such localization. The workflow is implemented in the form of an open-source simulation framework that is able to jointly account for the mobility of the nanodevices, in-body THz communication between with on-body anchors, and energy-related and other technological constraints (e.g., pulse-based modulation) at the nanodevice level. Accounting for these constraints, the framework is able to generate the raw data that can be streamlined into different flow-guided localization solutions for generating standardized performance benchmarks.

研究动机与目标

• 为早期流动引导纳米级定位研究中缺乏客观、可比较的性能评估提供解决方案。
• 防止早期室内定位研究中出现的陷阱，例如指标、环境和性能指标不一致的问题。
• 通过标准化场景、指标和环境，建立通用的评估框架，实现对定位解决方案的公平比较。
• 模拟现实约束条件，包括太赫兹通信范围、能量采集、间歇性运行以及血流中的移动性。
• 通过可重用、开源的仿真器，使社区能够客观地基准测试并改进流动引导定位解决方案。

提出的方法

• 开发一种仿真工作流，将纳米设备在血流中的移动性与体内太赫兹通信（连接到体表锚点）相结合。
• 使用ZnO纳米线和基于脉冲的调制，对纳米设备的能量采集和间歇性运行进行建模。
• 实现一个框架，在一致条件下生成多种定位解决方案的原始数据。
• 采用先前工作的改进方法，模拟事件检测，包括基于区域的定位及左右模糊性消除。
• 将结果简化为标准化性能指标，如可靠性、区域检测准确率和基于质心估计的点准确率。
• 引入随时间变化的能量水平追踪，以支持能量感知的任务调度与优化。

Figure 1: Nanodevice mobility in the BloodVoyagerS [ 13 ]

实验结果

研究问题

• RQ1 如何为流动引导纳米级定位建立标准化性能评估，以实现客观比较？
• RQ2 不可靠的太赫兹通信和能量采集约束对定位准确率有何影响？
• RQ3 在流动引导场景中，定位延迟如何影响可靠性与准确率？
• RQ4 尽管纳米设备在目标区域循环，移动性和路径变异性在多大程度上会导致事件检测遗漏？
• RQ5 当区域检测不可靠时，如何有意义地报告区域检测准确率和点准确率等性能指标？

主要发现

• 所评估解决方案的区域检测准确率最高为40%，且随着定位延迟增加，仅获得微小提升。
• 当延迟从2分钟增加到15分钟时，定位可靠性从低于50%提升至90%以上，表明其对观测时间有强烈依赖。
• 即使在区域检测错误的情况下，点准确率仍被呈现，揭示了先前基准测试方法中的系统性缺陷，可能导致性能解读误导。
• 纳米节点的时间依赖能量水平显示其因能量采集约束而呈现间歇性运行，影响传感和传输的可用性。
• 不可靠的太赫兹通信和间歇性运行是所评估场景中定位性能不佳的主要原因。
• 所提出的框架成功捕捉了真实系统动态，并实现了不同定位解决方案之间客观、可重复的基准测试。

Figure 2: Categorization of RF-based in-body localization approaches, corresponding applications, their requirements, and relevant performance metrics