Practical localization system for consumer devices using zigbee networks

As the era of ubiquitous computing dawns, there is a growing need for a reliable, efficient positioning and tracking system. A localization system involves ongoing tracking of the location of assets and personnel. This paper presents a practical localization system for consumer devices on Zigbee networks. The proposed system is based on time-difference-of-arrival (TDOA). Localization based on TDOA involves estimating the location of the device by calculating the time-difference-of-arrival of the signal received from a device. In order to calculate the time difference of the signal, TDOA-based methods require precision time measurements of the signal, and reader time synchronization accurate to within a few nanoseconds. We also propose a precise time stamping unit, which enables the system to determine the arrival time of the radio signal, and a precision time synchronization protocol, which enables readers to have a reference clock. In addition, this paper includes an experimental performance evaluation of the localization system. The performance shows that the localization system has a DRMS of approximately two meters in a harsh environment.