The growing interest for indoor position-based applications and services, as well as ubiquitous computing and location aware information, have led to increasing efforts toward the development of positioning techniques. Many applications require accurate positioning or tracking of people and assets inside buildings, and some market sectors are waiting for such technologies for starting a fast growth. Ultrasonic systems have already been shown to possess the desired positioning accuracy and refresh rate. However, they still require accurate synchronization between ultrasound emitters and receivers to work properly. Usually, synchronization is carried out through radio frequency (RF) signals, adding system complexity and raising the cost. In this work, this limit is overcome by introducing a novel self-synchronizing indoor positioning technique. Ultrasonic signals travel from emitters placed at fixed reference positions to any number of mobile devices (MD). The travelled distance is computed from the time of flight (TOF), which requires in turn synchronism between emitter and receiver. It is shown that this synchronism can be indirectly estimated from the time difference of arrival (TDOA) of the ultrasonic signals. The obtained positioning information is private, in the sense that the positioning infrastructure is not aware of the number or identity of the MDs that use it. Computer simulations and experimental results obtained in a typical office room are provided.

中文翻译：

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超声波室内定位的移动同步恢复。

人们对基于室内位置的应用程序和服务以及无处不在的计算和位置感知信息的兴趣日益浓厚，这导致人们越来越致力于定位技术的开发。许多应用程序要求对建筑物内的人员和资产进行精确的定位或跟踪，并且某些市场部门正在等待此类技术开始快速发展。超声波系统已经显示出具有所需的定位精度和刷新率。但是，它们仍然需要超声发射器和接收器之间的准确同步才能正常工作。通常，同步是通过射频（RF）信号进行的，这增加了系统复杂性并增加了成本。在这项工作中，通过引入一种新颖的自同步室内定位技术克服了这一限制。超声波信号从放置在固定参考位置的发射器传播到任意数量的移动设备（MD）。行进距离是从飞行时间（TOF）计算得出的，这又需要发射器和接收器之间进行同步。示出了可以从超声信号的到达时间差（TDOA）间接估计这种同步。在定位基础结构不知道使用它的MD的数量或身份的意义上，所获得的定位信息是私有的。提供了在典型办公室中获得的计算机模拟和实验结果。这又需要发射器和接收器之间的同步。示出了可以从超声信号的到达时间差（TDOA）间接估计这种同步。在定位基础结构不知道使用它的MD的数量或身份的意义上，所获得的定位信息是私有的。提供了在典型办公室中获得的计算机模拟和实验结果。这又需要发射器和接收器之间的同步。示出了可以从超声信号的到达时间差（TDOA）间接估计这种同步。在定位基础结构不知道使用它的MD的数量或身份的意义上，所获得的定位信息是私有的。提供了在典型办公室中获得的计算机模拟和实验结果。