Techniques for indoor positioning systems (IPSs) can be categorised as range-based or range-free. Range-based methods rely on geometric mappings to approximate a location given the calculated distances or angles from multiple reference points. In contrast, range-free strategies utilise fingerprinting, wherein an acquired fingerprint data is compared to a pre-collected dataset to identify the best position estimate. Among these, fingerprinting of channel state information (CSI) is preferred over other information such as received signal strength indicator as the former can exploit the effect of multipath propagation and is robust against non-line-of-sight channels. CSI has the potential to achieve cm-level positioning accuracy with a single reference point only. In this study, the authors survey CSI fingerprinting-based indoor positioning and mobility tracking systems. The process of fingerprinting that includes site surveying and signal preprocessing is discussed in detail. They determine the potential challenges of such systems and propose remedies to improve positioning accuracy. In general, spatial diversity, such as multiple-input multiple-output antennas and wireless sensor networks, or frequency diversity (e.g. high subcarrier count, frequency hopping mechanism) are exploited to achieve high positioning resolution. Such IPS can also be enhanced via additional sensors or spatial graphs for motion detection and tracking.

中文翻译：

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基于CSI指纹识别的室内定位和移动性跟踪系统的调查

室内定位系统（IPS）的技术可以分为基于范围的或无范围的。基于距离的方法在给定从多个参考点算起的距离或角度的情况下，依靠几何映射来近似某个位置。相反，无范围策略利用指纹识别，其中将获取的指纹数据与预先收集的数据集进行比较以识别最佳位置估计。其中，信道状态信息（CSI）的指纹识别优于其他信息（例如接收信号强度指示符），因为前者可以利用多径传播的效果，并且对非视距信道具有鲁棒性。CSI仅通过一个参考点就有可能达到cm级定位精度。在这个研究中，作者调查了基于CSI指纹识别的室内定位和移动性跟踪系统。详细讨论了包括现场勘测和信号预处理在内的指纹识别过程。他们确定了此类系统的潜在挑战，并提出了改善定位精度的补救措施。通常，利用空间分集（例如多输入多输出天线和无线传感器网络）或频率分集（例如，高子载波数，跳频机制）来实现高定位分辨率。还可以通过用于运动检测和跟踪的其他传感器或空间图来增强此类IPS。他们确定了此类系统的潜在挑战，并提出了改善定位精度的补救措施。通常，利用空间分集（例如多输入多输出天线和无线传感器网络）或频率分集（例如，高子载波数，跳频机制）来实现高定位分辨率。还可以通过用于运动检测和跟踪的其他传感器或空间图来增强此类IPS。他们确定了此类系统的潜在挑战，并提出了改善定位精度的补救措施。通常，利用空间分集（例如多输入多输出天线和无线传感器网络）或频率分集（例如，高子载波数，跳频机制）来实现高定位分辨率。还可以通过用于运动检测和跟踪的其他传感器或空间图来增强此类IPS。