Experimental determination of UWB ranging errors in an outdoor environment

Ultra-wideband (UWB) technology is a good candidate to provide accurate position information indoors and in dense urban environments where Global Positioning System (GPS) is usually not reliable. This paper provides the results of a UWB ranging measurement campaign carried out in a dense urban environment. Measurements were taken with two different antenna heights in line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. It is observed that the ranging errors increases when the antennas are closer to the ground, and is more significant in NLOS conditions. Also, in NLOS conditions ranging errors of more than 10 meters were observed when the LOS component is completely blocked by a building. Errors of such magnitude are typically not captured by IEEE 802.15.4a CM6 (outdoor NLOS) channel model. Since the conventional thresholding schemes provide bad ranging accuracy in presence of multiuser interference (MUI), we propose a nonlinear processing scheme of time-hopping impulse radio (TH-IR) and apply it to our measurements to show that it gives much better ranging accuracy.