Indoor positioning systems have received increasing attention for supporting location-based services in indoor environments. Wi-Fi based indoor localisation has become attractive due to its extensive distribution and low cost properties. IEEE 802.11-2016 now includes a Wi-Fi Fine Time Measurement (FTM) protocol which can be used for Wi-Fi ranging between intelligent terminal and Wi-Fi access point. This paper introduces a framework of Wi-Fi FTM data acquisition and processing that can be used for indoor localisation. We analyse the main factors that affect the accuracy of Wi-Fi ranging and propose a calibration, filtering and modelling algorithm that can effectively reduce the ranging error caused by clock deviation, non-line-of-sight (NLOS) and multipath propagation. Experimental results show that the proposed calibration and filtering method is able to achieve metre-level ranging accuracy in case of line-of-sight by using large bandwidth. Estimation results also show that the proposed Wi-Fi ranging model provides an accurate ranging performance in NLOS and multipath contained indoor environment; the final positioning error is less than 2·2 m with a stable output frequency of 3 Hz.

中文翻译：

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Wi-Fi 精细时间测量：室内定位的数据分析和处理

室内定位系统由于支持室内环境中的基于位置的服务而受到越来越多的关注。基于 Wi-Fi 的室内定位由于其广泛的分布和低成本的特性而变得很有吸引力。IEEE 802.11-2016 现在包括 Wi-Fi 精细时间测量 (FTM) 协议，可用于智能终端和 Wi-Fi 接入点之间的 Wi-Fi 测距。本文介绍了可用于室内定位的 Wi-Fi FTM 数据采集和处理框架。我们分析了影响 Wi-Fi 测距精度的主要因素，提出了一种校准、滤波和建模算法，可以有效降低由时钟偏差、非视距 (NLOS) 和多径传播引起的测距误差。实验结果表明，所提出的校准和滤波方法能够在使用大带宽的视距情况下达到米级的测距精度。估计结果还表明，所提出的 Wi-Fi 测距模型在 NLOS 和包含多径的室内环境中提供了准确的测距性能；最终定位误差小于2·2 m，稳定输出频率为3 Hz。