Non-Line of Sight Detection by Temporal Channel Impulse Response Tracking

Abstract:
Ultra wide-band (UWB) radio attracted interest for implementing real-time localization systems (RTLS). A major improvement compared to narrow-band RTLS is that the line of sight (LOS) path can be detected even in harsh multipath fading environments. However, this advantage is annulled when the LOS path is obstructed. Non-line of sight (NLOS) components will be interpreted as first received path which results in wrong, biased range measurements. This paper proposes an algorithm that detects the absence of the LOS path. This is achieved by tracking peaks in the channel impulse response (CIR) obtained by auto-correlating received UWB pulses. Using this knowledge, NLOS measurements can be rejected in order to improve the overall positioning accuracy.