Implication of anchor placement on performance of UWB real-time locating system

Recently, real-time locating system (RTLS) with centimeter accuracy using radio frequency signal is available for commercial deployment with the use of ultra-wideband (UWB) technology. One of the commercial UWB real time locating systems in the market now is DecaWave's DW1000 IC which utilizes two-way-ranging (TWR) mechanism to measure accurate distance between an anchor and a tag. Then, a trilateration algorithm with distances from three or more anchors is used to calculate the tag's location. It is recommended that, to improve the accuracy of the system, a clear view between all anchors must be provided. This work presents a performance study of commercial UWB RTLS evaluation kits in two different anchor placement scenarios. In the first scenario, each anchor was provided a clear communication path between each other while in the latter some direct communication paths between the anchors were obstructed by concrete pillars. The evaluation kits were configured to allow maximum range and data rate. Intuitively, the first scenario should perform much better than the latter. However, the experiments showed the contrary in some situations. Moreover, the overall performance, in terms of error distances and R95 values, of the first scenario did not outperform significantly as expected.