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  • Research Article
  • Open Access

NLOS Identification and Weighted Least-Squares Localization for UWB Systems Using Multipath Channel Statistics

  • 1Email author,
  • 1,
  • 1 and
  • 1
EURASIP Journal on Advances in Signal Processing20072008:271984

  • Received: 30 March 2007
  • Accepted: 21 July 2007
  • Published:


Non-line-of-sight (NLOS) identification and mitigation carry significant importance in wireless localization systems. In this paper, we propose a novel NLOS identification technique based on the multipath channel statistics such as the kurtosis, the mean excess delay spread, and the root-mean-square delay spread. In particular, the IEEE 802.15.4a ultrawideband channel models are used as examples and the above statistics are found to be well modeled by log-normal random variables. Subsequently, a joint likelihood ratio test is developed for line-of-sight (LOS) or NLOS identification. Three different weighted least-squares (WLSs) localization techniques that exploit the statistics of multipath components (MPCs) are analyzed. The basic idea behind the proposed WLS approaches is that smaller weights are given to the measurements which are likely to be biased (based on the MPC information), as opposed to variance-based WLS techniques in the literature. Accuracy gains with respect to the conventional least-squares algorithm are demonstrated via Monte-Carlo simulations and verified by theoretical derivations.


  • Localization Technique
  • Delay Spread
  • Multipath Channel
  • Publisher Note
  • Theoretical Derivation

Publisher note

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Authors’ Affiliations

DoCoMo Communications Laboratories USA, Inc., 3240 Hillview Avenue, Palo Alto, CA 94304, USA


© İsmail Güvenç et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.