AI 中文总结
针对无晶体BLE无线电的引导校准难题，本文提出轻量级方法LightCal，利用商用HTC Lighthouse V1基站的光脉冲作时序参考，在scum平台实现了实用的BLE引导校准，降低了IoT节点成本与复杂度。
AI 中文摘要
无晶体蓝牙低功耗（BLE）无线电移除了片外高频晶体振荡器，因此可降低物联网（IoT）节点的成本、尺寸与集成复杂度。然而，它们面临一个根本性的引导问题：节点通过射频（RF）通信前，必须先获得足够准确的载波频率参考。现有方法通常依赖射频信标、已连接节点或基于搜索的信道获取，这些方法会导致启动延迟过长，且当初始载波偏移较大时反馈有限。本文提出LightCal，一种轻量级引导校准方法，使用周期性光脉冲作为无晶体BLE无线电的外部时序参考。LightCal专为资源高度受限的平台设计，仅需简单的光脉冲接收。我们在scum（一款无晶体IoT平台）上实现LightCal，并使用商用HTC Lighthouse V1基站作为未修改的现成光脉冲源。实验结果显示，脉冲累加大幅提升了SCμM上Lighthouse同步脉冲的有效时序稳定性，实现了实用的BLE引导校准。在当前scum原型中，光校准将射频载波带入有界的残余误差范围，剩余偏移通过窄范围发射时间精细扫描解决。结果表明，光脉冲参考可为无晶体、高度集成的IoT平台提供实用的射频前引导校准路径。
英文摘要
Crystal-free Bluetooth Low Energy (BLE) radios remove the off-chip high-frequency crystal oscillator and can therefore reduce the cost, size, and integration complexity of Internet of Things (IoT) nodes. However, they face a fundamental bootstrap problem: before a node can communicate over RF, it must first obtain a sufficiently accurate carrier-frequency reference. Existing approaches typically rely on RF beacons, already-connected nodes, or search-based channel acquisition, which can incur long startup latency and provide limited feedback when the initial carrier offset is large. This paper presents LightCal, a lightweight bootstrap calibration method that uses periodic optical pulses as an external timing reference for crystal-free BLE radios. LightCal is designed for highly resource-constrained platforms and requires only simple optical pulse reception. We implement LightCal on scum, a crystal-free IoT platform and use a commercial HTC Lighthouse V1 base station as an unmodified off-the-shelf optical pulse source. Experimental results show that pulse accumulation substantially improves the effective timing stability of Lighthouse sync pulses on SC$μ$M and enables practical BLE bootstrap calibration. In the current scum prototype, optical calibration brings the RF carrier into a bounded residual-error range, and the remaining offset is resolved by a narrow transmit-time fine sweep. The results demonstrate that optical pulse references can provide a practical pre-RF bootstrap calibration path for crystal-free and highly integrated IoT platforms.
Comments6 pages,to be published in IEEE Globecom 2026
