NLOS identification in UWB channel for indoor positioning

Indoor positioning technology has received much attention in a field of the internet of things (IoT), and various technology such as Bluetooth low energy (BLE), WiFi fingerprinting, and ultra-wideband (UWB) have been studied for positioning. Among these technology, the UWB provides features of a low power consumption and high positioning accuracy caused by good immunity to multi-path fading. However, the performance of positioning feature is deteriorated in non-line of sight (NLOS) channel. Therefore, the identification of non-line of sight (NLOS) in UWB channel is required to verify and enhance the effects of UWB positioning. In this paper, we identify NLOS by measuring signal strengths on the first path and multi-path and estimate the distance from UWB anchor to a tag in through-the-wall and hard-NLOS channels. The results show that the proposed algorithm efficiently identified NLOS in UWB channel environments.