Recently, round-trip time (RTT) measured by a fine-timing measurement protocol has received great attention in the area of WiFi positioning. It provides an acceptable ranging accuracy in favorable environments when a line-of-sight (LOS) path exists. Otherwise, a signal is detoured along with non-LOS paths, making the resultant ranging results different from the ground-truth, called an RTT bias, which is the main reason for poor positioning performance. To address it, we aim at leveraging the user mobility trajectory detected by a smartphone's inertial measurement units, called pedestrian dead reckoning (PDR). Specifically, PDR provides the geographic relation among adjacent locations, guiding the resultant positioning estimates' sequence not to deviate from the user trajectory. To this end, we describe their relations as multiple geometric equations, enabling us to render a novel positioning algorithm with acceptable accuracy. Depending on the mobility pattern being linear or arbitrary, we develop different algorithms divided into two phases. First, we can jointly estimate an RTT bias of each AP and the user's step length by leveraging the geometric relation mentioned above. It enables us to construct a user's relative trajectory defined on the concerned AP's local coordinate system. Second, we align every AP's relative trajectory into a single one, called trajectory alignment, equivalent to transformation to the global coordinate system. As a result, we can estimate the sequence of the user's absolute locations from the aligned trajectory. Various field experiments extensively verify the proposed algorithm's effectiveness that the average positioning error is approximately 0.369 (m) and 1.705 (m) in LOS and NLOS environments, respectively.

翻译：最近,在WiFi定位领域,通过微微调测量协议测量的圆际时间(RTT)在WiFi定位领域受到极大关注。当存在直观(LOS)路径时,它为有利的环境中提供了一个可接受的范围精确度。否则,信号会与非透线路径相绕,使得由此产生的一系列结果与地面图不同,称为RTT偏差,这是定位性能差的主要原因。为了解决这个问题,我们的目标是利用智能手机惯性测量单位(称为行人死亡计算(PDR))所测得的用户流动性轨迹。具体地说,PDR提供相邻地点之间的地域关系,指导结果定位估计的顺序不会偏离用户轨迹。为了达到这个目的,我们将其关系描述为多重几何方方方方形方程,使我们能够以可接受的准确性进行新的定位算法。根据移动模式的线性或任意性,我们开发了不同的算法,分为两个阶段。首先,我们可以通过利用上述的直径直径比系统来估算每个用户的RTT的轨道偏差偏差值(行距)和用户的步长长度。它让我们分别将一个用户的轨道定位定位定位定位定位定位定位定位定位定位定位定位定位定位定位到一个特定的轨道定位系统。它成为了。