Performance Analysis of Wireless Clock Synchronization for a UWB Observed TDoA System

Abstract

The field of Real-Time Locationing Systems (RTLS) is ever-increasing, and there are many new technologies that are being used to implement object location tracking devices. While many of these devices rely on different forms of radio waves, one stands out in particular for its accuracy: that which is based on the Ultra-Wideband radio frequency. While in the field of RTLS, GPS may have a larger market share (due to its wide area coverage and the utilization of cost-free Global Positioning Satellites) it has a fatal weakness, and that is the limitation of the technology where a clear simultaneous line of sight is not available with four different satellites. For locations such as indoors and in dense cityscapes, this is a critical flaw. Hence, the importance of other RTLS comes into play. While many other possibly applicable forms of RTLS exist (WiFi, ZigBee, RFID), these lack performance in the accuracy aspect, and therefore are not viable in applications where sub-centimeter accuracy is required. This is where the UWB system comes into effect, as its ultra-wideband usage of the radio wave bands allows a short chirp communications, allowing a resolution never achieved before (within 5 mm in favorable conditions). Such a system is implemented using four or more anchors, which are relative location infrastructure systems that allow an object within its bounds to be tracked. This paper will cover the aspects of such a locationing system, focusing on experimentation with achievable accuracy. It will show results of CEPs of up to a few millimeters, and will show timing synchronization, which is necessary between the anchors, or LAPs.