Distributed ISAC systems - multisensor radio access and coordination. - In: 2023 20th European Radar Conference, (2023), S. 351-354
Integrated sensing and communication (ISAC) qualifies mobile radio systems for detecting and localizing of passive objects by means of radar sensing. Advanced ISAC networks rely on distributed infrastructure, multisensor uplink and downlink, or meshed sidelink access. In this way, ISAC develops into a MS-MIMO (multisensor multiple input multiple output) network which constitutes a distributed MIMO radar network. Multisensor link coordination and synchronization are becoming crucial. Many multisensor access and signaling techniques find their communication counterpart in multiuser MIMO and cooperative multilink communications (CoMP) and can be adopted from there.
https://doi.org/10.23919/EuRAD58043.2023.10289611
Numerical synthesis of radar target detections based on measured reference data. - In: 2023 20th European Radar Conference, (2023), S. 26-29
Virtual validation methods strive to reduce the testing efforts of automated driving functions significantly. However, assuring the fidelity of deployed sensor models based on objective criteria remains an unsolved challenge, especially for radar target detection point clouds, since they are subject to major stochastic fluctuations.This work focuses on the scenario-based derivation of requirements for synthetic radar target detections, which are deduced from sensor data recorded in real-world test drives. Based on these reference data, deviations between the radar point clouds from different recordings are quantified using metrics for both point clouds from single measurement cycles and relative probability distributions for accumulated point clouds. Finally, the suitability of the calculated reference values as adequate metrics of deviations between recorded and simulated sensor data is evaluated.
https://doi.org/10.23919/EuRAD58043.2023.10289571
Mutual over-the-air frequency synchronization of continuous wave signals. - In: 2023 20th European Radar Conference, (2023), S. 363-366
Future communication and radar sensing systems will require synchronization methods which are more versatile in terms of the systems involved in the synchronization process. We present an over-the-air frequency synchronization algorithm based on self-synchronization which uses continuous wave signals. In contrast to other approaches, all nodes of the network participate equally, and synchronization can even be achieved in presence of a non-cooperative node. These claims are supported by measurements conducted with continuous wave radars. It will be demonstrated that our algorithm enables synchronization accuracies down to 1.92 ppb and thus could provide sufficient accuracy for velocity measurements on pedestrians.
https://doi.org/10.23919/EuRAD58043.2023.10289292
Bi-isotropic prolate rotational ellipsoid in a homogeneous axial electric field. - In: 2023 58th International Scientific Conference on Information, Communication and Energy Systems and Technologies (ICEST), (2023), S. 261-264
A bi-isotropic prolate rotational ellipsoid in a homogeneous axial electric field is considered in this paper. By solving of Laplace's and Poisson's equation, the expressions for electric and magnetic scalar potential and electric and magnetic field, inside and outside of an ellipsoid, are completely determined. In the case of bi-isotropic parameter equal to zero, they reduce to known expressions of a pure dielectric ellipsoid. Polarization in the bi-isotropic ellipsoid is determined as well.
https://doi.org/10.1109/ICEST58410.2023.10187315
Robust reflective beamforming for non-terrestrial networks under thermal deformations. - In: IEEE ICASSPW 2023 workshop proceedings, (2023), insges. 5 S.
In this paper, we present a beamforming method that is robust against thermal deformations for non-terrestrial reconfigurable intelligent surfaces (RIS). We analytically derive the expressions for the worst-case bound on perturbations of the covariance matrix and the corresponding steering vectors as functions of possible displacements of RIS elements. We apply these bounds during the optimization procedure to find the beamforming coefficients that are robust to thermal deformations. Moreover, we present a simple heuristic to obtain the constant modulus beamforming coefficients from the optimal beamforming via an array thinning operation. The simulation results confirm the robustness of the proposed solution against random but bounded perturbations caused by thermal deformations of the reflective surface.
https://doi.org/10.1109/ICASSPW59220.2023.10193299
Time variant directional multi-link channel sounding and estimation for V2X. - In: 2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring), (2023), insges. 5 S.
We present our new scalable multi-channel and multi-node sounder, the ILMSound G3 . It is configurable in terms of the number of switched Tx and parallel Rx nodes. The basic structures of the Tx and Rx nodes are given with consideration of the measurement system requirements.The ILMSound G3 is validated via a proof of concept measurement at 2.53 GHz in an urban environment. The system was configured as a sounder with two Tx nodes and one Rx node, which records two MIMO links simultaneously. Each node uses an antenna array. The transmitters were moved by cars whereas the receiver was elevated 20 m above the ground by a lifting platform acting as a base station. The used system configuration results in a snapshot rate of approx. 0.5 kHz, which covers the expected time variance of the chosen environment.The measurement results were analyzed using HRPE, providing a parametric description of the specular propagation paths of the radio channel per measurement link. Each estimated path is described by its directions of departure and arrival, delay, Doppler shift, and fully polarimetric complex path weights.
https://doi.org/10.1109/VTC2023-Spring57618.2023.10199213
Sensing resources reduction for vehicle detection with integrated sensing and communications. - In: 2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring), (2023), insges. 5 S.
Integrated Sensing and Communications (ISAC) aims at incorporating radar and communications functionalities into a single system, achieving higher spectral efficiency through their joint operation. This paper proposes a methodology for reducing resource elements and scanning beams used in the target detection stage of ISAC. Building upon the well-known symbol domain Orthogonal Frequency Division Multiplexing (OFDM) ISAC processing algorithm, its relevant characteristics and limits are considered to minimize the periodicity of sensing resource elements. Moreover, a methodology for finding the required beams to sense a scenario using the radar range equation in a link-budget analysis is proposed and later illustrated via simulations. The simulations show that it is possible to cover a road scenario using a limited number of beams and resource elements from a New Radio (NR) OFDM frame.
https://doi.org/10.1109/VTC2023-Spring57618.2023.10199358
Combination of measurement and simulation for fast virtual drive testing. - In: 2023 IEEE International Symposium on Antennas and Propagation (and USNC-URSI Radio Science Meeting), (2023), S. 25-26
Virtual Drive Test (VDT) is an area of great interest for both scientific research and industry. The objective of VDT is to emulate a real-world communication testing by approximation of defined conditions. VDT can be performed in measurement facilities with over-the-air approaches and channel emulation techniques [1] [2], by simulation-based software-in-the-loop tests [3] or by combining measurement and simulation [4]. For all possible solutions, the challenge of the scientific community is to look for an automated, controllable, repeatable, and reliable procedure, which can considerably reduce testing time and costs. In this paper we present a new VDT technique to evaluate the V2X communications performances based on the combination of measurement and simulation. In particular, the radiation performance of a DUT representing the antenna under test installed on a vehicle is tested in a measurement facility, the radiation pattern (vehicle equipped by the antenna) is integrated in a simulation of a realistic scenario to reproduce a real-world communication testing. The accuracy of the method is validated by comparison with results of measured data from Field Operational Test (FoT) of LTE links [5] [6].
https://doi.org/10.1109/USNC-URSI52151.2023.10237776
Traffic flow regulation using vehicular communication. - Ilmenau. - 78 Seiten
Technische Universität Ilmenau, Masterarbeit 2023
Die hohe Zunahme des Verkehrsaufkommens aufgrund der gestiegenen Anzahl von Autos, Lastwagen, Bussen und anderen Fahrzeugen in den letzten Jahren hat Probleme wie Verkehrsüberlastung, erhöhte Unfallgefahr und die Möglichkeit von Unfällen bei widrigen Wetterbedingungen verschärft. Der dringende Bedarf an intelligenter Verkehrsflussoptimierung und an der Verbesserung der Verkehrssicherheit ist zu einem vorrangigen Anliegen geworden, das effektiv durch die Nutzung modernster Technologien wie Intelligent Transportation Systems (ITS) basierend auf Vehicle-to-Infrastructure (V2I)-Lösungen angegangen werden kann. Zur Verbesserung der Verkehrssicherheit ist es unerlässlich, Herausforderungen im Zusammenhang mit der Schätzung der Verkehrsdichte und der Regulierung der Verkehrsgeschwindigkeit anzugehen. Die Integration der V2I-basierten Kommunikation zwischen Infrastruktur-Road Side Units (RSUs) und den Fahrzeugen kann die Bedenken hinsichtlich der Verkehrsoptimierung effektiv durch die Verbreitung von empfohlenen Geschwindigkeitsbegrenzungen angehen. Diese Arbeit stellt einen neuartigen Ansatz zur Geschwindigkeitsbegrenzungsschätzung für jede Fahrspur auf einer mehrspurigen Autobahn vor. Dies wird durch die Implementierung eines Fahrspurerkennungsalgorithmus erreicht, der es den Fahrzeugen ermöglicht, kontinuierlich Echtzeitverkehrsdaten über die spezifische Fahrspur, auf der sie sich gerade befinden, mit den RSUs zu teilen. Die geteilten Daten werden dann von den RSUs verwendet, um die fahrspezifischen Verkehrsdichten zu berechnen. Anschließend bestimmt die RSU die Geschwindigkeitsbegrenzung der Fahrspuren und sendet die empfohlene Geschwindigkeitsbegrenzung je nach verschiedenen Szenarien an die Fahrzeuge. Die generierten Simulationsergebnisse zeigen das Potenzial der geschwindigkeitsbasierten Regelung in verschiedenen Szenarien auf. Durch Qualitätsanalysen ist ersichtlich, dass die Geschwindigkeitsregelung in einem mehrspurigen Szenario die Verkehrssicherheit unter besonderen Umständen verbessern kann. Dies führt wiederum zu einem verbesserten Verkehrsfluss. Zusammenfassend kann die Nutzung von ITS-basierten V2I-Lösungen zur Verkehrsoptimierung und Verbesserung der Verkehrssicherheit beitragen.
Erzeugung von Hochspannungspulsen für die Ansteuerung einer Pockels-Zelle. - Ilmenau. - 89 Seiten
Technische Universität Ilmenau, Masterarbeit 2023
Pockels-Zellen werden zur Modulation von Photonen verwendet und sind ein wesentlicher Bestandteil von Quantencomputern. Herkömmliche Pockels-Zellen-Treiber weisen jedoch bisher eine maximale Pulsrate von nur 100 kHz auf. In dieser Arbeit wurde daher eine Treiberschaltung mit einer höheren Pulsrate für Pockels-Zellen entworfen. Diese besteht aus zwei Teilschaltungen: Die erste erzeugt eine Hochspannung von mehr als 500 V auf der Basis einer Diodenmultiplizierer-topologie; die zweite stellt einen aus zwei zusammengeschalteten GaN-Transistoren aufgebauten Schalter dar, der aus der erzeugten Hochspannung Pulse bildet. Durch messtechnische Verifizierung wurde für die erste Teilschaltung der zum Schalten erforderliche Laststrom und für die zweite die Verlustleistung als begrenzender Parameter ermittelt. Die Arbeit liefert damit einen wichtigen Grundbaustein als Ausgangspunkt für die Entwicklung zukünftiger Pockels-Zellen mit höheren Pulsraten.