Hannotier Cédric, Horlin François, Quitin François
Brussels School of Engineering, Université libre de Bruxelles, Avenue Franklin Roosevelt 50, 1000 Brussels, Belgium.
Sensors (Basel). 2024 Jan 23;24(3):737. doi: 10.3390/s24030737.
Localization of wireless transmitters is traditionally done using Radio Frequency (RF) sensors that measure the propagation delays between the transmitter and a set of anchor receivers. One of the major challenges of wireless localization systems is the need for anchor nodes to be time-synchronized to achieve accurate localization of a target node. Using a reference transmitter is an efficient way to synchronize the anchor nodes Over-The-Air (OTA), but such algorithms require multiple periodic messages to achieve tight synchronization. In this paper, we propose a new synchronization method that only requires a single message from a reference transmitter. The main idea is to use the Carrier Frequency Offset (CFO) from the reference node, alongside the Time of Arrival (ToA) of the reference node messages, to achieve tight synchronization. The ToA allows the anchor nodes to compensate for their absolute time offset, and the CFO allows the anchor nodes to compensate for their local oscillator drift. Additionally, using the CFO of the messages sent by the reference nodes and the target nodes also allow us to estimate the speed of the targets. The error of the proposed algorithm is derived analytically and is validated through controlled laboratory experiments. Finally, the algorithm is validated by realistic outdoor vehicular measurements with a software-defined radio testbed.
传统上，无线发射器的定位是通过射频（RF）传感器来完成的，这些传感器测量发射器与一组锚点接收器之间的传播延迟。无线定位系统的主要挑战之一是需要锚点节点进行时间同步，以实现目标节点的精确定位。使用参考发射器是一种通过空中（OTA）同步锚点节点的有效方法，但此类算法需要多个周期性消息才能实现紧密同步。在本文中，我们提出了一种新的同步方法，该方法仅需要来自参考发射器的单个消息。主要思想是利用来自参考节点的载波频率偏移（CFO）以及参考节点消息的到达时间（ToA）来实现紧密同步。ToA允许锚点节点补偿其绝对时间偏移，而CFO允许锚点节点补偿其本地振荡器漂移。此外，利用参考节点和目标节点发送消息的CFO还使我们能够估计目标的速度。通过解析推导了所提算法的误差，并通过受控实验室实验进行了验证。最后，使用软件定义无线电测试平台通过实际户外车辆测量对该算法进行了验证。
