Estimating multi-modal dense multipath components using auto-encoders. - In: 30th European Signal Processing Conference (EUSIPCO 2022), (2022), S. 1716-1720
We present a maximum-likelihood estimation algorithm for radio channel measurements exhibiting a mixture of independent Dense Multipath Components. The novelty of our approach is in the algorithms initialization using a deep learning architecture. Currently, available approaches can only deal with scenarios where a single mode is present. However, in measurements, two or more modes are often observed. This much more challenging multi-modal setting bears two important questions: How many modes are there, and how can we estimate those? To this end, we propose a Neural Net-architecture that can reliably estimate the number of modes present in the data and also provide an initial assessment of their shape. These predictions are used to initialize for gradient- and model-based optimization algorithm to further refine the estimates. We demonstrate numerically how the presented architecture performs on measurement data and analytically study its influence on the estimation of specular paths in a setting where the single-modal approach fails.
https://ieeexplore.ieee.org/document/9909796
Time-domain analysis of ultra-wideband scattering properties of fruits. - In: 2022 19th European Radar Conference, (2022), S. 77-80
In the present paper we evaluate scattering properties of fruits measured with a short-range Ultra-Wideband radar. This is part of our investigation how effectively such a radar can be used to infer information such as fruit biomass or ripeness in an agricultural environment. The covered frequency band spans from 1.4 to 5.6 GHz. We analyze measured impulse responses of a watermelon, a grapefruit, and an apple with respect to a dependency on the distance between radar and fruit and the observation angle i.e., rotation of the fruit. Measurements are performed under laboratory conditions, however, we analyze the data considering a pre-harvest analysis on a field. It becomes apparent that an analysis of the dispersed dominant reflection of the peel is most promising. Due to the natural growth and hence anisotropy of the fruits, we conclude to average over multiple monostatic observation angles to reduce the natural variations of e.g. the scattered power.
https://doi.org/10.23919/EuRAD54643.2022.9924720
Link budget and design approach of a non-terrestrial 5G automotive antenna. - In: 2022 52st European Microwave Conference, (2022), S. 864-867
5G low-earth orbiting satellites are continuously increasing attention from automotive industry for automated and connected driving. Compactness of user equipment antennas and high data rates are key performance figures for efficient satellite communication systems. Here, we present a link budget for internet-of-things applications at Ka-band frequencies (5G frequency range FR2). Anticipating a realistic high-gain satellite antenna, an uplink data rate of 4 Mbit/s can be achieved with a compact user terminal antenna with a moderate gain of 13 dBi. Along these lines, a 4×4 patch antenna array was designed for seamless embedding in the plastic part of a car body, in order to verify the link budget calculations by experiment. The radiation performance was measured under free-space conditions and with the antenna embedded in the rear spoiler wing of a modern passenger car. The array offered 11.2 dBi realized gain and 1.6 GHz of −10 dB matching bandwidth, with an uplink data rate of 2 Mbit/s, promising for many mobility applications.
https://doi.org/10.23919/EuMC54642.2022.9924379
Evaluation of scenario-based automotive radar testing in virtual environment using real driving data. - In: 2022 IEEE 25th International Conference on Intelligent Transportation Systems (ITSC), (2022), S. 2379-2384
Safety assurance of intended functionality through rigorous testing is a key to large-scale homologation and deployment of automated driving. It is therefore imperative to transfer real world tests into efficient and quantifiable virtual testing procedures and environments without compromising reliability. In earlier work, we presented a fully operational over-the-air vehicle-in-the-loop test system for automotive millimeter-wave radar, where we generated a virtual electromagnetic environment with physically realistic radar target echoes. We evaluated the performance of the implemented test system with an exemplary scenario parameterised with analytically pre-defined vehicle manoeuvres. In this work, we significantly proceed with the performance evaluation through re-simulation of scenarios based on real driving data and traffic manoeuvres. We have measured a standard Euro-NCAP scenario, namely, the Car-to-Pedestrian Longitudinal Adult on a proving ground and re-simulated the ground truth parameters in the test bed. We compare the consistency of the test results at several data abstraction levels using parameter trajectories. Additionally, we introduce and evaluate quality metrics such as difference and root mean square error. For a driving scenario approximately 20 seconds long, we achieved promisingly low root mean square errors in range, azimuth and RCS of 0.3 m, 0.5˚ and 2 dB, respectively.
https://doi.org/10.1109/ITSC55140.2022.9922366
Enable SDRs for real-time MIMO channel sounding featuring parallel coherent Rx channels. - In: 2022 IEEE 95th Vehicular Technology Conference (VTC2022-Spring), (2022), insges. 5 S.
A parallel receiver architecture for multiple input multiple output (MIMO) channel sounding application is presented with a software-defined radio (SDR)-based field-programmable gate array (FPGA) implementation. The receiver covers phase coherent reception via shared local oscillator (LO) and reference clock, a timing scheme synchronous to the antenna switching at the transmitter, and an integrated automatic gain control (AGC) in all receive channels. It is built with SDRs (NI USRP-2955, X310 series with TwinRx daughterboards). The use of these off-the-shelf hardware components reduces the costs of the sounding system. The FPGA implementation together with the system parameters of the chosen hardware allows a minimum AGC update interval of approx. 44.38 μs. Our setup demonstrates the applicability of state-of-the-art SDRs as a sounding system for continuous acquisition of the time variant, space, and frequency selective radio propagation channel.
https://doi.org/10.1109/VTC2022-Spring54318.2022.9860841
From 3D point cloud data to ray-tracing multi-band simulations in industrial scenario. - In: 2022 IEEE 95th Vehicular Technology Conference (VTC2022-Spring), (2022), insges. 5 S.
In this paper, we present the ray tracing (RT) simulation in the 3D model of one highly dense clutter industrial hall, which is scanned by laser scanner and reconstructed based on accurate point cloud. The whole processing chain from the scanning of the physical environment to running the simulation is presented in detail. To validate the simulation results, the synthetic channel characteristics and large-scale parameters, including delay spread (DS), angular spread (AS) and path loss (PL), are compared with those obtained from channel sounding measurement in both LOS and NLOS cases, at 6.75 GHz, 30 GHz and 60 GHz. The simulation results show that some scatters are significant in all bands and may be well identified and tracked. This indicates that our target to generate a deterministic channel model or a hybrid channel model at multi-band for industrial scenario may be possible.
https://doi.org/10.1109/VTC2022-Spring54318.2022.9861002
Link budget considerations for automotive 5G LEO satellite-based communications. - In: 2022 IEEE USNC-URSI Radio Science Meeting (joint with AP-S Symposium), (2022), S. 106-107
Satellite communication receives strongly increasing attention for automated and connected driving. Compact size, low power consumption, and high data rates are key performance parameters for such systems. Based on realistic assumptions on user equipment terminal and satellite antenna for low-earth orbiting satellites using large space structures, we present relevant link budget considerations. The high-gain satellite antenna opens the potential to employ compact user equipment antennas of moderate gain and without beam tracking. We study selected C-, Ku-, and Ka-frequency bands for 5G satellite communications based upon usual key performance indicators. Our findings indicate that C-band and Ka-band offer a suitable spectrum, with an uplink data rate of 7 Mbit/s at Ka-band, which is suitable for IoT and broadband mobile access applications.
https://doi.org/10.23919/USNC-URSI52669.2022.9887406
Reflection design methods for reconfigurable intelligent surfaces-aided dynamic TDD systems. - In: 2022 IEEE 12th Sensor Array and Multichannel Signal Processing Workshop (SAM), (2022), S. 36-40
Dynamic time-division-duplexing (DTDD) and reconfigurable intelligent surfaces (RISs) have been proposed recently as solutions to meet the small cells traffic fluctuations and to tune the wireless propagation channels in real-time, respectively. However, to the best of the authors' knowledge, there has been no work so far considering the integration of both techniques. Therefore, we consider in this paper an RIS-aided DTDD wireless system and propose two non-iterative methods to design the RIS reflection vector with the objective of maximizing the system spectral efficiency, while reducing the cross-link interference. Numerical results are presented showing the efficiency of the proposed methods as compared to some baseline schemes. It is shown that the integration of RIS in DTDD systems has great potential in improving communication efficiency while reducing the impact of cross-link interference.
https://doi.org/10.1109/SAM53842.2022.9827850
Enhanced computation of the coupled block-term decomposition in multilinear rank terms. - In: 2022 IEEE 12th Sensor Array and Multichannel Signal Processing Workshop (SAM), (2022), S. 400-404
Coupled tensor decompositions proved to be a valuable tool for many signal processing applications, including biomedical data analysis, source separation, data fusion, and many others. In this paper, we present an algorithm to calculate the coupled (BTD) of multiple three-dimensional tensors with a coupled mode and possibly an unknown rank structure. The proposed approach is composed of three main parts, the first is an extension of the linear regression of global eigenvalues (LaRGE) technique to estimate the number of blocks and sum of multilinear ranks in the coupled tensors. The second part accounts for the calculation of the preliminary multilinear factors of the coupled BTD by means of the semi-algebraic framework for approximate CP decompositions via simultaneous matrix diagonalizations (SECSI). The last part contains the final refinement procedures that return the estimated BTD factors. Moreover, we provide some synthetic data simulations showing that the proposed algorithm demonstrates more stable and accurate results than the schemes from the literature.
https://doi.org/10.1109/SAM53842.2022.9827801
Combining AI/ML and PHY layer rule based inference - some first results. - In: 2022 IEEE 23rd International Workshop on Signal Processing Advances in Wireless Communication (SPAWC), (2022), insges. 5 S.
In 3GPP New Radio (NR) Release 18 we see the first study item starting in May 2022, which will evaluate the potential of artificial intelligence and machine learning (AI/ML) methods for Radio Access Network (RAN) 1, i.e., for mobile radio PHY and MAC layer applications. We use the profiling method for an accurate iterative estimation of the parameters of the dominant multipath components, as it promises a large channel prediction horizon. We investigate options to partly or fully replace some functionalities of rule based PHY layer algorithms by AI/ML inferences, with the goal to achieve either a higher performance, lower latency, or reduced processing complexity. We provide first results for noise reduction, then a combined scheme for model order selection, compare options to infer multipath component start parameters, and provide an outlook on a possible channel prediction framework.
https://doi.org/10.1109/SPAWC51304.2022.9833980