An Extended Kalman Filter for Direct, Real-Time, Phase-Based High Precision Indoor Localization

Lipka M, Sippel E, Vossiek M (2019)

Publication Language: English

Publication Type: Journal article, Review article

Publication year: 2019


Book Volume: Volume 7

Pages Range: 25288-25297

Journal Issue: Issue 1

DOI: 10.1109/ACCESS.2019.2900799


Radio-based indoor localization is currently a very vibrant scientific research field with many
potential use cases. It offers high value for customers, for example, in the fields of robotics, logistics and
automation, or in context-aware IT services. Especially for autonomous systems, dynamic human-machine
interaction or augmented reality applications, precise localization coupled with a high update rate are key. In
this paper, we present a completely novel localization concept whereby received radio signal phase values
that are fed into an Extended Kalman Filter (EKF) without any preprocessing are evaluated. Standard
preprocessing steps, like angle-of-arrival (AOA) estimation, beamforming, time-of-flight (TOF) or timedifference-
of-arrival (TDOA) estimations are not required with this approach. The innovative localization
concept benefits from the high sensitivity of radio signals’ phase to distance changes and the fast and
straightforward recursive computation offered by the EKF. It completely forgoes the computational burden
of other phase-based high-precision localization techniques, like synthetic aperture methods. To verify
the proposed method, we use an exemplary setup employing a 24 GHz frequency modulated continuous
wave (FMCW) single input multiple output secondary radar with 250 MHz bandwidth. A high precision
6-axis robotic arm serves as a 3D positioning reference. The test setup emulates a realistic industrial indoor
environment with significant multipath reflections. Despite the challenging conditions and the rather low
bandwidth, the results show an outstanding localization 3D RMSE of around 1.7 cm. The proposed method
can easily be applied to nearly any type of radio signal with CW carrier and is an attractive alternative
to common multilateration and multiangulation localization approaches. We think it is a quantum leap in
wireless locating, as it has the potential for precise, simple and low-cost wireless localization even with
standard narrowband communication signals.

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How to cite


Lipka, M., Sippel, E., & Vossiek, M. (2019). An Extended Kalman Filter for Direct, Real-Time, Phase-Based High Precision Indoor Localization. IEEE Access, Volume 7(Issue 1), 25288-25297.


Lipka, Melanie, Erik Sippel, and Martin Vossiek. "An Extended Kalman Filter for Direct, Real-Time, Phase-Based High Precision Indoor Localization." IEEE Access Volume 7.Issue 1 (2019): 25288-25297.

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