A Robust Indoor Localization Method for NLOS Environments Utilizing Sensor Subsets

Indoor location localization using the time of arrival (TOA) of ultra-wideband (UWB) radio waves faces a challenge in obtaining accurate TOA values in a non-line-of-sight (NLOS) environment owing to obstacles and multipath reception. The accuracy of localization using such sensor data in an NLOS environment is significantly degraded. To address this problem in NLOS environment, we proposed a new localization method that utilizes different sensor combinations for estimation and sensor placement topology. Based on the conventional localization method using various combinations of sensors, the estimation results containing an NLOS ranging value were first removed. Subsequently, we introduced a new parameter called the topological expectancy of localization accuracy (TELA), which represents the effect of sensor placement on the accuracy of localization. The final estimation result was then obtained using the weighted average of the remaining localization results obtained by TELA. Computer simulations and experimental results showed that the performance of the proposed method is superior by 4 to 37% compared with that of conventional methods, even in the presence of many NLOS environment sensors.