Spread Spectrum based Localization of UHF RFID Tags

Knowing the position of an RFID tag is an enabler for a variety of applications. While localization can easily be managed with ultra-wideband systems, it is rather difficult for typical UHF RFID systems: The mostly passive (batteryless) tags lack precise oscillators and are primarily targeted for narrowband application. After introducing basic concepts of ranging and localization, this talk will introduce a spread spectrum based ranging method, using time-of-flight measurements. The regulatory requirements are discussed, performance boundaries are derived, an evaluation platform is introduced, and measurement results are presented. Finally, the extension of the ranging method to a MIMO-configuration is shown and the increased performance is discussed.