In positioning research based on the orthogonal frequency division multiplex (OFDM) system, the observed time difference of arrival positioning method is a widely studied direction. The terminal measures the reference signal sent by the base station to calculate the time of arrival (TOA). Using TOA information, the location of the terminal can be identified. So the accuracy of the positioning is highly dependent on the results of the TOA measurements. Terminals often have difficulty measuring accurate TOA due to multipath channels and occlusion of obstacles. This study proposes two clustering-based TOA estimation methods. The cluster-based Max-peak estimator is used to solve the problem that the energy of the first-path is not the strongest in the case of multipath. Moreover, a cluster-based adaptive threshold estimator is used to estimate TOA when the power of the direct path is low. The joint estimator of the two methods is designed to improve estimation accuracy. The proposed method is tested in the OFDM localisation environment, and the results demonstrate that the proposed method has better performance than the conventional way.

中文翻译：

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基于聚类的OFDM系统中到达时间估计

在基于正交频分复用（OFDM）系统的定位研究中，到达定位方法的观测时差是一个广泛研究的方向。终端测量基站发送的参考信号，以计算到达时间（TOA）。使用TOA信息，可以识别终端的位置。因此，定位的精度高度依赖于TOA测量的结果。由于多径通道和障碍物的堵塞，终端通常难以测量准确的TOA。这项研究提出了两种基于聚类的TOA估计方法。基于聚类的最大峰值估计器用于解决在多径情况下第一路径的能量不是最强的问题。此外，当直接路径的功率低时，基于簇的自适应阈值估计器用于估计TOA。两种方法的联合估计器旨在提高估计精度。在OFDM定位环境下对该方法进行了测试，结果表明该方法具有比传统方法更好的性能。