Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Nov 2;17(11):2522.
doi: 10.3390/s17112522.

Indoor Multipath Assisted Angle of Arrival Localization

Stijn Wielandt  1 , Lieven De Strycker  2
Affiliations

Indoor Multipath Assisted Angle of Arrival Localization

Stijn Wielandt et al. Sensors (Basel). .

Abstract

Indoor radio frequency positioning systems enable a broad range of location aware applications. However, the localization accuracy is often impaired by Non-Line-Of-Sight (NLOS) connections and indoor multipath effects. An interesting evolution in widely deployed communication systems is the transition to multi-antenna devices with beamforming capabilities. These properties form an opportunity for localization methods based on Angle of Arrival (AoA) estimation. This work investigates how multipath propagation can be exploited to enhance the accuracy of AoA localization systems. The presented multipath assisted method resembles a fingerprinting approach, matching an AoA measurement vector to a set of reference vectors. However, reference data is not generated by labor intensive site surveying. Instead, a ray tracer is used, relying on a-priori known floor plan information. The resulting algorithm requires only one fixed receiving antenna array to determine the position of a mobile transmitter in a room. The approach is experimentally evaluated in LOS and NLOS conditions, providing insights in the accuracy and robustness. The measurements are performed in various indoor environments with different hardware configurations. This leads to the conclusion that the proposed system yields a considerable accuracy improvement over common narrowband AoA positioning methods, as well as a reduction of setup efforts in comparison to conventional fingerprinting systems.

Keywords: NLOS localization; angle of arrival (AoA); antenna arrays; indoor positioning system (IPS); multipath assisted localization.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Architecture of the localization process with a single anchor node.
Figure 2
Figure 2
ULA system model.
Figure 3
Figure 3
Example measurement vectors.
Figure 4
Figure 4
Multipath effect at a smooth and large material boundary.
Figure 5
Figure 5
Simulated rays in a room of 5 m by 5 m with brick walls.
Figure 6
Figure 6
Fingerprint examples.
Figure 7
Figure 7
LOS fingerprint example: fLOS,i for θLOS=68∘.
Figure 8
Figure 8
Example surface probability density functions.
Figure 9
Figure 9
Example of two merged SPDF vectors.
Figure 10
Figure 10
SPDF example for a NLOS measurement, resulting in a large localization error ϵloc and a small surface interval.
Figure 11
Figure 11
Overview of the test environments.
Figure 12
Figure 12
Evaluation of the mean surface interval (a) and mean normalized errors (b) as a function of the number of array elements (M).
Figure 13
Figure 13
Optimal amount of spatial smoothing.
Figure 14
Figure 14
Evaluation of system performance for multiple antenna arrays with all-LOS to all-NLOS connections.
See this image and copyright information in PMC

References

    1. Klepeis N.E., Nelson W.C., Ott W.R., Robinson J.P., Tsang A.M., Switzer P., Behar J.V., Hern S.C., Engelmann W.H. The National Human Activity Pattern Survey (NHAPS): A resource for assessing exposure to environmental pollutants. J. Expo. Anal. Environ. Epidemiol. 2001;11:231–252. doi: 10.1038/sj.jea.7500165. - DOI - PubMed
    1. Li B., Rizos C. Editorial. J. Locat. Based Serv. 2014;8:1–2. doi: 10.1080/17489725.2013.870419. - DOI
    1. Kolodziej K.W., Hjelm J. Local Positioning Systems: LBS Applications and Services. CRC Press; Boca Raton, FL, USA: 2006.
    1. Kupper A. Location-Based Services: Fundamentals and Operation. John Wiley & Sons; New York, NY, USA: 2005.
    1. Liu H., Darabi H., Banerjee P., Liu J. Survey of wireless indoor positioning techniques and systems. IEEE Trans. Syst. Man Cybern. Part C Appl. Rev. 2007;37:1067–1080. doi: 10.1109/TSMCC.2007.905750. - DOI