Modelling micro-Doppler signature of drone propellers in distributed ISAC. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 6 S.
Integrated Sensing and Communication (ISAC) comprises detection and analysis of non-cooperative targets by exploiting the resources of the mobile radio system. In this context, micro-Doppler is of great importance for target classification, in order to distinguish objects with local movements. For developing algorithms for target classification, it is necessary to have a large amount of target signatures. Aiming to generate these data, this paper proposes a mathematical model for the micro-Doppler of drone rotating propellers, and validate the proposed model by comparing it to measured micro-Doppler. Results show that the proposed mathematical model can generate micro-Doppler data very similar to those from measurement data.
https://doi.org/10.1109/RadarConf2458775.2024.10548468
Improving the spatial correlation characteristics of antenna arrays using linear operators and wide-band modelling. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), S. 67-73
The analysis of wireless communication channels at the mmWave, sub-THz and THz bands gives rise to difficulties in the construction of antenna arrays due to the small maximum inter-element spacing constraints at these frequencies. Arrays with uniform spacing greater than half the wavelength for a certain carrier frequency exhibit aliasing side-lobes in the angular domain, prohibiting non-ambiguous estimates of a propagating wave-front’s angle of arrival.In this paper, we present how wide-band modelling of the array response is useful in mitigating this spatial aliasing effect. This approach aims to reduce the grating lobes by exploiting the angle- and frequency-dependent phase-shifts observed in the response of the array to a planar wave-front travelling across it.Furthermore, we propose a method by which the spatial correlation characteristics of an array operating at 33 GHz carrier frequency with an instantaneous bandwidth of 1 GHz can be improved such that the angular-domain side-lobes are reduced by 5-10 dB. This method, applicable to arbitrary antenna array manifolds, makes use of a linear operator that is applied to the base-band samples of the channel transfer function measured in space and frequency domains. By means of synthetically simulated arrays, we show that when operating with a bandwidth of 1 GHz, the use of a derived linear operator applied to the array output results in the spatial correlation characteristics approaching those of the array operating at a bandwidth of 12 GHz. Hence, non-ambiguous angle estimates can be obtained in the field without the use of expensive high-bandwidth RF front-end components.
https://doi.org/10.1109/WSA61681.2024.10511328
Excitation signal design for THz channel sounding and propagation parameter estimation. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 5 S.
In this publication, we analyze how the performance of propagation parameter estimation for THz channel sounding can be improved by the power spectrum design of a multicarrier waveform. To this end, we discuss the Fisher information of the propagation parameters and the corresponding deterministic Cramèr-Rao lower bound (CRB) as well as their relation to the carrier powers of the excitation signal. We use these quantities to design waveforms that improve range estimation. In practice, evaluating the Fisher information requires prior knowledge of the propagation scenario which is usually unavailable. Hence, we propose two solutions which we compare numerically to the classical approach of equal power distribution. The evaluation shows that an optimized power distribution can improve the CRB comparable up to a 4 dB gain in signal-to-noise ratio (SNR) if knowledge about the propagation scenario is available and slightly less if the scenario is unknown.
https://doi.org/10.23919/EuCAP60739.2024.10501423
Characterization of propagation from measurements at sub-THz for ISAC applications in an emulated dynamic industrial scenario. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 5 S.
The large blocks of free instantaneous bandwidth at (sub-)THz and the utilization of high gain radio interfaces makes the (sub-)THz suitable for sensing applications. In this paper we present the analysis of novel dual-polarized double directional measurements at 190 GHz in an industrial setting with integrated sensing and communication applications in view. The set-up consists of a bi-static configuration emulating two access points with beam-steering capabilities in a machine room. One access point serves a machine with a wireless link, while the other access point senses the environment to detect moving objects. The objective is to detect possible obstructions that could interrupt the communication link or cause accidents on the production line. The results have shown that the system aspects as narrow beams and large bandwidths allow the early identification of objects in the environment from the measured channel impulse response.
https://doi.org/10.23919/EuCAP60739.2024.10501207
Ray tracing and measurement-based characterization of inter/intra-machine THz wireless channels. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 5 S.
We characterize the wireless propagation channels at 300 GHz in an industrial environment through measurements and ray tracing simulations. Two different scenarios are considered representing wireless connections between an access point and an industrial machine (inter-machine scenario), and between two components inside the same machine (intra-machine scenario) are considered. For both scenarios, we compute the channel response in terms of power angle delay profile and compare the results obtained through measurements and simulations, which show a good match.
https://doi.org/10.23919/EuCAP60739.2024.10501627
Grid-free harmonic retrieval and model order selection using convolutional neural networks. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 5 S.
Harmonic retrieval techniques are the foundation of radio channel sounding, estimation and modeling. This paper introduces a Deep Learning approach for joint delay- and Doppler estimation from frequency and time samples of a radio channel transfer function. Our work estimates the two-dimensional parameters from a signal containing an unknown number of paths. Compared to existing deep learning-based methods, the signal parameters are not estimated via classification but in a quasi-grid-free manner. This alleviates the bias, spectral leakage, and ghost targets that grid-based approaches produce. The proposed architecture also reliably estimates the number of paths in the measurement. Hence, it jointly solves the model order selection and parameter estimation task. Additionally, we propose a multi-channel windowing of the data to increase the estimator's robustness. We also compare the performance to other harmonic retrieval methods and integrate it into an existing maximum likelihood estimator for efficient initialization of a gradient-based iteration.
https://doi.org/10.23919/EuCAP60739.2024.10501588
Shut off! - hybrid BICMOS logic for power-efficient high speed circuits. - In: SMACD 23, (2023), insges. 4 S.
Power efficiency is crucial, especially in high-speed systems, where conventional approaches like clock gating cannot be employed readily. Special logic families, such as Positive Emitter-Coupled Logic (PECL), push the technological frontier, promising even more speed at the expense of an even more strained power budget. We propose a novel hybrid of PECL and Complementary Metal-Oxide-Semiconductor (CMOS) logic to introduce Function Shut-off (FSO), realizing a shut-off at the level of functional blocks and logic primitives inside complex logic cells. Using this approach, we realize a high-speed Linear Feedback Shift Register (LFSR) in a SiGe technology, extending the State of the Art (SOTA) by adding reconfigurability, which is required for its use as sequence generator in Compressed Sensing (CS) applications. We present measurements showing successful fabrication and performance of the packaged die at 20.4 GHz. In this LFSR, employing FSO reduces the supply current by a factor of up to four (depending on the chosen configuration) and reduces active area by 17%.
https://doi.org/10.1109/SMACD58065.2023.10192217
Characterization of propagation in an industrial scenario from sub-6 GHz to 300 GHz. - In: IEEE Xplore digital library, ISSN 2473-2001, (2023), S. 1475-1480
We perform simultaneous multi-band ultra-wideband dual-polarized double-directional measurements at sub-6 GHz (center frequency, 6.75 GHz), mmWave (74.25 GHz), and sub-THz (305.27 GHz) in line of sight (LOS) and non-LOS in a small industrial scenario (machine room). The aim is to characterize the propagation at THz taking as a reference the lower bands and identifying shared and distinguishing features. The spatial/temporal analysis of the measurements shows strong similarities in multi-path components (MPCs) between the different bands. Moreover, high order reflections have been identified at THz. Overall, the results indicate that THz channels exhibit significant multipath, with some specular MPCs unique to the band and with lower contribution by the diffuse components. Finally, path-loss has also been computed and compared with existing multi-band models.
https://doi.org/10.1109/GCWkshps58843.2023.10464485
Autoencoder-based learning of transmission parameters in fast pulse-echo ultrasound imaging employing sparse recovery. - In: 2023 IEEE 9th International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), (2023), S. 516-520
There is recently a notable rise in the exploration of pulse-echo ultrasound image reconstruction techniques that address the inverse problem employing sparse signal and rely on a single measurement cycle. Nevertheless, these techniques continue to pose significant challenges with regard to accuracy of estimations. Previous studies have endeavored to decrease the correlation between received samples in each transducer array in order to enhance accuracy of sparsely approximated solutions to inverse problems. In this paper, our objective is to learn the transmission parameters within a parametric measurement matrix by employing an autoencoder, which encodes sparse spatial data with a parametric measurement matrix and subsequently decodes it using Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). Outcomes exhibit superior performance in comparison to both state-of-art random selection of the parameters and conventional plane wave imaging (PWI) scenarios in terms of reconstruction accuracy.
https://doi.org/10.1109/CAMSAP58249.2023.10403443
Data-driven subsampling matrices design for phased array ultrasound nondestructive testing. - In: IEEE IUS 2023, International Ultrasonics Symposium, Palais des congrès de Montréal, September 3-8, 2023, (2023), insges. 4 S.
By subsampling optimally in the spatial and temporal domains, ultrasound imaging can achieve high performance, while also accelerating data acquisition and reducing storage requirements. We study the design of experiment problem that attempts to find an optimal choice of the subsampling patterns, leading to a non-convex combinatorial optimization problem. Recently, deep learning was shown to provide a feasible approach for solving such problems efficiently by virtue of the softmax function as a differentiable approximation of the one-hot encoded subsampling vectors. We incorporate softmax neural networks into information theory-based and task-based algorithms, respectively, to design optimal subsampling matrices in Full Matrix Capture (FMC) measurements predicated on compressed sensing theory.
https://doi.org/10.1109/IUS51837.2023.10308257