University of Oulu

O. L. A. López, D. Kumar and A. Tölli, "Polarization Diversity-Enabled LOS/NLOS Identification via Carrier Phase Measurements," in IEEE Transactions on Communications, vol. 71, no. 3, pp. 1678-1690, March 2023, doi: 10.1109/TCOMM.2023.3236381.

Polarization diversity-enabled LOS/NLOS identification via carrier phase measurements

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Author: López, Onel L. A.1; Kumar, Dileep1; Tölli, Antti1
Organizations: 1Centre for Wireless Communications, University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.7 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2023
Publish Date: 2023-01-17


The provision of accurate localization is an increasingly important feature of wireless networks. To this end, a reliable distinction between line-of-sight (LOS) and non-LOS (NLOS) radio links is necessary to avoid degenerative localization estimation biases. Interestingly, LOS and NLOS transmissions affect the polarization of the received signals differently. In this work, we leverage this phenomenon to propose a threshold-based LOS/NLOS classifier exploiting weighted differential carrier phase measurements over a single link with different polarization configurations. Operation in either full or limited polarization diversity systems is possible. We develop a framework for assessing the performance of the proposed classifier, and show through simulations the performance impact of the reflecting materials in NLOS scenarios. For instance, the classifier is far more efficient in NLOS scenarios with wooden reflectors than in those with metallic reflectors. Numerical results evince the potential performance gains from exploiting full polarization diversity, properly weighting the differential carrier phase measurements, and using multi-carrier/tone transmissions. Finally, we show that the optimum decision threshold is inversely proportional to the path power gain in dB, while it does not depend significantly on the material of potential NLOS reflectors.

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Series: IEEE transactions on communications
ISSN: 0090-6778
ISSN-E: 1558-0857
ISSN-L: 0090-6778
Volume: 71
Issue: 3
Pages: 1678 - 1690
DOI: 10.1109/tcomm.2023.3236381
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This research has been supported by the Academy of Finland under Grant 346208 (6G Flagship) and by the Finish Foundation for Technology Promotion.
Academy of Finland Grant Number: 346208
Detailed Information: 346208 (Academy of Finland Funding decision)
Copyright information: © The Author(s) 2023. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see