Circularly polarized patch antenna array for 5G automotive satellite communications. - In: 2023 53rd European Microwave Conference, (2023), S. 794-797
5G low-earth orbit (LEO) satellite communication plays a crucial role in enhancing the reliability and coverage of wireless connectivity for automated and connected driving. Compactness of user equipment antennas presents a key requirement for automotive mass-market applications offering non-terrestrial connectivity in addition to terrestrial mobile communications. Latest studies reveal the potential for moderate-gain antenna terminals for such applications. We present a circularly polarized 4 × 4 patch antenna array operating at a center frequency of 2S GHz in the 5G new-radio band n257 suitable for LEO satellite communications. The antenna is feasible for integration into the rear spoiler of a car, roof-top shark-fin antenna, or other plastic-covered antenna mounting locations. The embedded array offers 12 dBi measured realized gain and 4 GHz of -10 dB impedance bandwidth. It offers a 3-dB axial-ratio bandwidth of 900 MHz, demonstrating its circular polarization purity along the broadside direction. Realistic link budget calculations predict an uplink data rate of 6 Mbit/s, promising for various automotive mobility applications.
https://doi.org/10.23919/EuMC58039.2023.10290591
Deep learning based positioning with beamformed CSI fingerprints. - In: Proceedings of the 2023 13th International Conference on Indoor Positioning and Indoor Navigation (IPIN), (2023), insges. 6 S.
User positioning with deep learning (DL) models based on channel state information (CSI) fingerprints, e.g., obtained at a base station (BS), has emerged as a promising technology. Related prior works generally assume a CSI fingerprint with multiple spatial dimensions (i.e antennas or beams) at the BS but only a single spatial dimension at the user equipment (UE). However, a UE may be equipped with multiple antennas or may need to perform beamforming, e.g., to support transmissions at higher frequencies. In this work we consider user positioning with DL models based on uplink beamformed CSI fingerprints considering multiple spatial dimensions at both the BS and the UE. By considering a single or multiple beams at the BS and UE, the use of different CSI fingerprints is proposed. The positioning accuracy achieved with the different beamformed CSI fingerprints is evaluated and compared. The different orientation during training and UE deployment is also considered. In addition, we also consider the positioning of UEs with different spatial capabilities, i.e. with different number of beams. This work provides valuable insights into the design of wireless positioning with CSI fingerprints considering multiple spatial dimensions at both the BS and UE.
https://doi.org/10.1109/IPIN57070.2023.10332494
Demonstration and validation of a 3D wave field synthesis setup for multiple GNSS satellite emulation via over-the-air testing. - In: AMTA 2023 proceedings, (2023), insges. 10 S.
Wireless devices supporting global navigation satellite systems (GNSS) services have become an essential tool in different areas of technology such as agriculture, construction, automotive, etc. Therefore the performance and reliability of such devices are important aspects that need to be addressed in the testing stage during the development of the units. The integration of the Over-the-Air (OTA) testing method with the 3D Wave Field Synthesis (3DWFS) technique offer not only the benefit of having tests under controllable and repeatable conditions but also the ability to recreate complex and realistic scenarios in a controlled environment with full polarimetric support for the testing of wireless devices. This contribution applies this technology to emulate a GNSS scenario within an anechoic chamber. For the results validation, a realistic GNSS outdoor scenario was recorded and compared with the emulated scenario where 3DWFS was applied for each individual satellite. This represents a significant step for the GNSS community and also for the future development and testing of wireless devices.
https://doi.org/10.23919/AMTA58553.2023.10293372
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