Researches On UWB Indoor Localization Based On Improved TDOA Method

Impulse Radio Ultra-wideband (IR-UWB) is a newly emerged short rangewireless technology which is quite different with traditional wireless techniques. Ithas attracted great intention by researchers from academy and industry, for its wideapplication in communication, precise ranging and positioning, detection, imagingand so on. Based on time difference of arrival (TDOA) method, indoor localizationusing UWB signals will be studied in this paper. Aiming at the difficulties of anchornode synchronization for standard TDOA method, an improved TDOA method isproposed. Performance analysis and optimization of this method are made. Themain contents of this paper are as follows:The existing time-of-arriva l-based UWB localization methods are introduced,which include time-of-arrival-based method, time-sum-of-arrival-based and time-difference-of-arrival-based method. The advantages of standard TDOA methodrelated to the other methods are pointed out.Aiming at the difficulty of synchronization for standard TDOA method, animproved TDOA method is proposed, Cramer-Rao lower bound (CRLB) of thismethod is derived as performance benchmark. Results show that there is2dB loss inperformance compared to standard TDOA method, however, no synchronizationrequirement exists in the improved method, the complexity of the system is greatlyreduced.The performance of the improved-TDOA-based localization is optimized, theimpact of clock drift and anchor node configuration on the proposed method isanalyzed, the factors that affect the performance of UWB positioning system issummarized through formula derivation and simulation results, anchor nodeconfiguration optimization is analyzed too. Results show that there exists an radiuswhich optimizes the localization performance, and closed-form expression for theoptimal radius and localization area radius is given, which can be used as areference in practical UWB positioning system design.