Bluetooth Low Energy (BLE) location trackers, or "tags", are popular consumer devices for monitoring personal items. These tags rely on their respective network of companion devices that are capable of detecting their BLE signals and relay location information back to the owner. While manufacturers claim that such crowd-sourced approach yields accurate location tracking, the tags' real-world performance characteristics remain insufficiently understood. To this end, this study presents a comprehensive analysis of three major players in the market: Apple's AirTag, Samsung's SmartTag, and Tile. Our methodology combines controlled experiments -- with a known large distribution of location-reporting devices -- as well as in-the-wild experiments -- with no control on the number and kind of reporting devices encountered, thus emulating real-life use-cases. Leveraging data collection techniques improved from prior research, we recruit 22 volunteers traveling across 29 countries, examining the tags' performance under various environments and conditions. Our findings highlight crucial updates in device behavior since previous studies, with AirTag showing marked improvements in location report frequency. Companion device density emerged as the primary determinant of tag performance, overshadowing technological differences between products. Additionally, we find that post-COVID-19 mobility trends could have contributed to enhanced performance for AirTag and SmartTag. Tile, despite its cross-platform compatibility, exhibited notably lower accuracy, particularly in Asia and Africa, due to limited global adoption. Statistical modeling of spatial errors -- measured as the distance between reported and actual tag locations -- shows log-normal distributions across all tags, highlighting the need for improved location estimation methods to reduce occasional significant inaccuracies.

翻译：低功耗蓝牙（BLE）位置追踪器（或称"标签"）是用于监控个人物品的流行消费设备。这些标签依赖各自配套设备组成的网络，这些配套设备能够检测其BLE信号并将位置信息中继给物主。尽管制造商声称这种众包方法能实现精准定位，但标签在实际场景中的性能特征仍未得到充分理解。为此，本研究对市场三大主流产品进行了全面分析：苹果AirTag、三星SmartTag和Tile。我们的方法结合了受控实验（在已知大量位置上报设备分布的环境下）与野外实验（对遭遇的上报设备数量和类型无控制），从而模拟真实使用场景。利用改进自先前研究的数据收集技术，我们招募了22名志愿者在29个国家进行测试，考察标签在不同环境和条件下的表现。研究结果揭示了自先前研究以来设备行为的重要更新，其中AirTag在位置上报频率方面表现出显著提升。配套设备密度成为标签性能的主要决定因素，其重要性超过了产品间的技术差异。此外，我们发现后疫情时代的流动性趋势可能促进了AirTag和SmartTag的性能提升。Tile尽管具有跨平台兼容性，但由于全球采用率有限，在亚洲和非洲地区表现出明显较低的准确性。对空间误差（定义为上报位置与实际位置之间的距离）的统计建模显示，所有标签的误差均呈对数正态分布，这凸显了需要改进位置估计方法以减少偶发的重大误差。