Interference and Spoofer Resilient Attitude Estimation using Observations from Distributed Linear Sub-Arrays separated by Long Baselines

Marius Brachvogel, Michael Niestroj, Soeren Zorn, Michael Meurer, Syed N. Hasnain, Ralf Stephan, Matthias A. Hein

Abstract:	Dedicated antenna arrays and spatial signal processing techniques are the most effective countermeasures against radio interference or sophisticated spoofing attacks. Especially in the field of Global Navigation Satellite Systems (GNSS) their incorporation has recently raised attention as they allow to recognize a spoofy GNSS signal through a comparison of its spatial information measured at the antenna elements of the array with the decoded information from the satellite ephemeris data. If they do not match, the spoofer can be mitigated by pointing a null in its direction. For that purpose, the attitude of the array in the coordinate system of the ephemeris data is required to be known. Especially in the field of automated and connected driving driving, both aforementioned types of disturbances have to be detected and mitigated to ensure a continuously safe and reliable operation. Therefore, compact antenna arrays, such as conventional uniform rectangular arrays (URA), where the distance between adjacent antenna elements does not exceed half a carrier wavelength, are commonly used. A significant drawback is posed by the large size of such arrays, which impedes the installation in the consumer automotive area, where an aesthetic design is a unique selling point and hence strictly followed by industry. This paper emphasizes a new approach, where the conventional URA is split into uniform linear arrays (ULA), whose size allow for a hidden installation in the front and rear bumper of a car, which would otherwise not provide enough space for the entire large URA. Thereby the new array violates two assumptions, which are valid for compact arrays: The distance between adjacent antennas can reach up to the length of the car, resulting in spacings of 20 – 30 carrier wavelengths. Furthermore, the metallic car body, which carries and affects the array, has a severe impact on the received signal power levels, which can no longer be assumed to be equal at all antenna elements. There are mainly two established methods for GNSS-based attitude determination: On the one hand, there are methods developed for and tested on compact arrays, whose operation has not been tested on configurations as the proposed array, where the aforementioned assumptions are violated. On the other hand, there are real time kintematic (RTK) based approaches, which are utilizing double-differences of phase measurements from distributed GNSS receivers, which instead lack the possibility to mitigate interferences. Therefore, this paper presents an approach to determine the attitude of the newly proposed spatially distributed array, thereby providing the ability to use spatial signal processing techniques for interference mitigation and hence providing robustness in degraded environments. The accuracy of the algorithm is tested in a realistic scenario using a measurement of the manifold of the proposed array configuration mounted onto a car.
Published in:	Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019 Hyatt Regency Miami Miami, Florida
Pages:	3484 - 3497
Cite this article:	Brachvogel, Marius, Niestroj, Michael, Zorn, Soeren, Meurer, Michael, Hasnain, Syed N., Stephan, Ralf, Hein, Matthias A., "Interference and Spoofer Resilient Attitude Estimation using Observations from Distributed Linear Sub-Arrays separated by Long Baselines," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 3484-3497. https://doi.org/10.33012/2019.16930
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