Congress & Conference Contributions

In this paper we present the latest results of a research program on the use of ground penetrating radar and machine learning-based algorithms for humanitarian demining in Colombia. We describe the experimental setup developed, which includes a polarimetric GPR-UWB unit, a radar positioning system, and a control unit. We describe as well a soil characterization campaign and an IED classification technique based on Support Vector Machine.

Even though vehicular communication systems have been rolled out in road, they remain a prominent field of research and development. The functional and operational safety of vehicle-to-X system demands reliable and efficient methods for verification and validation, based on their functional principles and underlying wave-physical phenomena. To test such systems in virtual environment, we have undertaken empirical studies of the communication channel, to analyze parameters like distance and sight conditions in a rich multipath environment. This paper describes the results and conclusions derived from a set of field-operational tests along a track, with modules operating with ITS-G5. While the results confirm the expectation that field-operational tests aren't reproducible on a quantitative level, we have gained insight into fundamental constraints on the channel parameters and approaches towards emulation in virtual environment. Employing omni-directional roof-mounted antennas, we have observed reliable communication links for ranges up to 250 meters, independent of sight conditions.

The bottleneck in OTA testing electrically large equipment is the large number of sources required for sufficient angular density. That is, if the sources are active. In that case, high-bandwidth, high-frequency equipment with excellent stability, processing power, and configurability is needed per antenna element. The costs of scaling up the current MIMO OTA configuration to higher frequencies and/or large equipment is prohibitive. In case passive radiators are used, the maximum control speed is determined by the maximum expected Doppler frequency. Such performance is order of magnitudes cheaper, even for large numbers of elements. In this contribution, we will present a new OTA concept that uses passively radiating reconfigurable structures and is inherently bi-directional. The concept that we call Projection-OTA, accommodates test objects in FR1 that are electrically large to very large and shows good prospects for emulating beam dynamics for testing 5G NR in FR2. Whether such passive structures will be made up by reflect arrays, meta-surfaces, or even intelligent surfaces is to be determined. We will discuss the prospects and limitations of this concept.

While traditional testing methods as conducted and open field tests have their limitations in terms of realism and repeatability of the scenario's conditions, Over-the-Air (OTA) testing enhances the way that GNSS and mobile communications systems with integrated antennas are tested, since it provides the freedom to accurately emulate an impinging wave with arbitrary polarization and direction radiated from any source/reflection such as GNSS satellites and terrestrial base stations. Therefore, real world scenarios can be precisely reproduced with total control of the environment's conditions. In this context, this paper describes the process to implement full polarimetric 3D Wave Field Synthesis (WFS) in an OTA testbed, from the principle to characterize the electromagnetic (EM) field in three dimensions to the system calibration and correspondent verification measurements inside the anechoic chamber, which will provide a deeper insight on the quality and reliability of the EM field for testing purposes.

Automotive millimeter-wave radar systems are key to automated and connected driving technologies. It is necessary to validate their functional performance in the installed state thoroughly, reliably, and efficiently under realistic conditions before deploying them in real-world traffic. Field-operational tests are the ultimate phase of verification and validation of radar sensors. This approach offers the highest degree of realism yet consuming enormous resources and associated risks. Additionally, these drive tests are neither sufficiently reproducible nor controllable. On the other hand, computer simulation-based closed-loop test approaches overcome these limitations, but lack physically realistic environments. Therefore, over-the-air testing approaches have gained great relevance in this context. In earlier work, we proposed an advanced system concept using an over-the-air vehicle-in-the-loop (OTA/ViL) approach for evaluating the installed performance of fully operational automotive radar systems. In this paper, we present the complete test system in a closed loop in a virtual electromagnetic environment with realistic radar target echoes. An exemplary traffic scenario is considered to validate the performance of the implemented test system. Initial measurements provide promising results.