Accuracy of an UWB localization system based on a CMOS chip

In this paper, we analyze the achievable location accuracy of a high-precision localization system using time-difference-of-arrival measurements of ultra wide-band (UWB) pulses. This system is under development at our institute and based on a low-power CMOS chip. Similar commercially available localization systems achieve location accuracies (location error standard deviation) down to 15cm under line-of-sight conditions in a working range of 20m indoors (30cm in a 100m range outdoors). We review the fundamental limits of the ranging accuracy of any localization system satisfying the regulatory constraints for UWB emissions. Next, we incorporate realistic characteristics of the UWB radio channel and the CMOS receiver into the analysis. We show that the ranging accuracy is heavily influenced by the available signal-to-noise ratio, i.e., the distance between the antennas, and the multi-path nature of the UWB radio channel. The effect of sampling time jitter of the receiver clock is shown to be negligible. With our proposed system design a ranging accuracy down to 1cm in a working range of 40m can be achieved, which outperforms the accuracy of existing systems.