A New Two-Step Ranging Algorithm in NLOS Environment for UWB Systems

It is well known that non-line-of-sight (NLOS) is one of the main factors that affect the ranging accuracy of time-of-arrival (TOA) estimation. In order to reduce the ranging error caused by the NLOS, this paper proposes a two-step ranging method. Firstly, the received signal is averaged over multiple frames to reduce additive white Gaussian noise (AWGN), and then a rough TOA is obtained by detecting the peak of the correlated signal. Secondly, the two cross-correlations between the time-averaged waveform and the early-late gate signals are computed. Then an error signal can be obtained by using the difference of these two cross-correlation signals. Within the region of the rough TOA, the TOA of the first path is searched by detecting the first minimum square of the error signal. Simulation results show that our proposed method is prior to the traditional generalized maximum likelihood (GML) estimation under the NLOS environment