A Cluster-Based Statistical Channel Model for Integrated Sensing and Communication Channels

The emerging 6G network envisions integrated sensing and communication (ISAC) as a promising solution to meet growing demand for native perception ability. To optimize and evaluate ISAC systems and techniques, it is crucial to have an accurate and realistic wireless channel model. However, some important features of ISAC channels have not been well characterized, for example, most existing ISAC channel models consider communication channels and sensing channels independently, whereas ignoring correlation under the consistent environment. Moreover, sensing channels have not been well modeled in the existing standard-level channel models. Therefore, in order to better model ISAC channel, a cluster-based statistical channel model is proposed in this paper, which is based on measurements conducted at 28 GHz. In the proposed model, a new framework based on 3GPP standard is proposed, which includes communication clusters and sensing clusters. Clustering and tracking algorithms are used to extract and analyze ISAC channel characteristics. Furthermore, some special sensing cluster structures such as shared sensing cluster, newborn sensing cluster, etc., are defined to model correlation and difference between communication and sensing channels. Finally, accuracy of the proposed model is validated based on measurements and simulations

Study of electromagnetic wave propagation and scattering in Low-THz automotive radar

The development of a new generation of sensors for autonomous vehicles requires the increase of the number of automotive radars on the roads, leading to an inevitable problem of overcrowding of the electromagnetic spectrum in the allocated 77 GHz band. The solution proposed in this research is the migration of the automotive radar operation frequency towards the low-THz band. This thesis reports, firstly, an experimental study on the feasibility of deploying automotive radars working at frequencies above 100 GHz. The study analyses the possible additional attenuation of the electromagnetic waves in adverse weather conditions and the differences in targets reflectivities, in comparison to the performances of current automotive radars. A comprehensive library of reflectivity signatures of a number of road actors is established, to provide a basis for the development of low-THz automotive radars. Secondarily, the thesis discusses and demonstrates the advantages of the employment of low-THz signals to improve the imaging capability of automotive radars, to allow identification and classification of road targets based on high resolution images and micro-Doppler signatures

Low-THz Automotive 3D Imaging Radar

This thesis lays out initial investigations into the 3D imaging capabilities of low-THz radar for automotive applications. This includes a discussion of the state of the art of automotive sensors, and the need for a robust, high-resolution imaging system to compliment and address the short-comings of these sensors. The unique capabilities of low-THz radar may prove to be well-suited to meet these needs, but they require 3D imaging algorithms which can exploit these capabilities effectively. One such unique feature is the extremely wide signal bandwidth, which yields a fine range resolution. This is a feature of low-THz radar which has not been discussed or properly investigated before, particularly in the context of generating the 3D position of an object from range information. The progress and experimental verification of these algorithms with a prototype multi-receiver 300GHz radar throughout this project are described; progressing from simple position estimation to highly detailed 3D radar imaging. The system is tested in a variety of different scenarios which a vehicle must be able to navigate, and the 3D imaging radar is compared with current automotive demonstrators experimentally

Study of the bio-radar radio channel

Dissertação para obtenção do Grau de Mestre em Engenharia Eletrónica e de TelecomunicaçõesOs radares de Micro-Doppler têm sido amplamente utilizados para a aquisição remota de sinais vitais. Este tipo de radar é tipicamente denominado de Bio-Radar. A qualidade do sinal vital obtido está diretamente relacionada com a potência recebida, que pode ser inferida através da equação do radar. No entanto, existem outros aspetos que influenciam a potência recebida, especialmente quando o alvo de interesse está localizado próximo das antenas. Para melhor compreender a configuração ótima do radar, é necessário estudar a propagação do canal de rádio, cujo estudo tem sido escasso na literatura. Neste trabalho, foram realizadas simulações e experiências para caracterizar a variação da potência do sinal recebido, bem como a Secção Eficaz de Dispersão (RCS), de acordo com a distância em relação ao Bio-Radar. O trabalho realizado, que envolveu a realização de simulações e medições práticas em formas geométricas conhecidas, não só ajudou a validar o software utilizado nas simulações, mas também o método prático de medição da potência recebida realizado na câmara anecoica. Posteriormente, foi realizada uma análise em seres humanos, revelando que vários fatores poderiam influenciar os resultados obtidos, como a postura dos sujeitos e os seus padrões de respiração. No geral, para obter uma boa medida do sinal respiratório, distâncias mais curtas, até 1 metro, tendem a ser as mais adequadas.Micro-Doppler radars have been widely used for the remote vital signs acquisition. These type of radars are commonly known as Bio-Radar. The obtained vital signal quality is directly related with the received power, which can be inferred by using the radar equation. Nevertheless, there are other aspects that influence the received power, especially when the the target of interest is located near the antennas. To better understand the optimal radar configuration, it is necessary to study the propagation of the radio channel, whose study has been lacking in the literature. In this work, simulations and experiments were performed to characterise the received signal power variation as well as the Radar Cross Section (RCS), according to the distancie in relation to the Bio-Radar. The work performed, which involved conducting simulations and practical measurements on well-known shapes, has not only helped validate the software used in the simulations but also the practical measuring method of received power conducted in the anechoic chamber. Subsequently, an analysis was performed on human subjects, revealing that various factors could influence the ob tained results, such as the posture of the subjects and their breathing patterns. Overall, for improved respiratory signal measurement, shorter distances, up to 1 meter, tend to be the most adequate.N/

Propagation and scattering of electromagnetic waves in low THz band in automotive radar applications

This thesis, firstly, due to the lack of knowledge in influence of harsh outdoor environment on the performance of the low-THz automotive sensors, the investigation has been done to demonstrate the performance of low-THz sensors in the presence of different radome contaminants (mud, oil, grit, etc.) and various weather conditions (rain, snow, fog, etc.) to prove the feasibility of using low-THz frequencies (100 GHz -1 THz) in automotive radar in uncontrolled environmental conditions. Secondarily, this thesis reports and discuss the important and yet unsolved task on automotive surface recognition and shows the possibility of using Low THz radar for road surface classification by exploring the radar signal backscattering from surfaces with different roughness, and finally this thesis demonstrate the novel approach to surface classification based on the analysis of radar images obtained using the low THz imaging radar and demonstrate the advantage of low THz radar for surface discrimination for automotive sensing. The proposed experimental technique in combination with a convolutional neural network provides high surface classification accuracy

Modellbasierte Analyse des Interferenzverhaltens von Kfz-Radaren

Die steigende Anzahl verbauter Kfz-Radarsensoren verlangt nach einer Untersuchung von deren gegenseitiger Interferenz. Die vorliegende Arbeit liefert zu diesem Forschungsgebiet Beiträge in Form von Modellen und darauf aufbauenden Analysen. Die Auswirkung von Interferenz auf die Funktionalität von Radarsensoren wird diskutiert, unter anderem auf Basis einer virtuellen Testfahrt und ausgesuchten Szenarien. Zudem wird ein Vorschlag zum kombinierten Einsatz von Interferenz -Gegenmaßnahmen gegeben

Millimetre-wave radar development for high resolution detection

Automotive technology today is focusing on autonomous vehicle development. The sensors for these systems include radars due to their robustness against adverse weather conditions such as rain, fog, ash or snow. In this constant search for advancement, high resolution systems play a central role in target detection and avoidance. In this PhD project, these methods have been researched and engineered to leverage the best radar resolution for collision avoidance systems. The first part of this thesis will focus on the existing systems consisting of the state-of-the-art at the time of writing and explain what makes a high resolution radar and how it can cover the whole field of view. The second part will focus on how a non-uniform sparse radar system was simulated, developed and benchmarked for improved radar performance up to 40% better than conventional designs. The third part will focus on signal processing techniques and how these methods have achieved high resolution and detection: large virtual aperture array using Multiple Input Multiple Output (MIMO) systems, beampattern multiplication to improve side-lobe levels and compressive sensing. Also, the substrate-integrated waveguide (SIW) antennas which have been fabricated provide a bandwidth of 1.5GHz for the transmitter and 2GHz at the receiver. This has resulted in a range resolution of 10 cm. The four part of this thesis presents the measurements which have been carried out at the facilities within Heriot-Watt University and also at Netherlands Organisation for Applied Scientific Research (TNO). The results were better than expected since a two transmitter four receiver system was able to detect targets which have been separated at 2.2◦ in angle in the horizontal plane. Also, compressive sensing was used as a high resolution method for obtaining fine target detection and in combination with the multiplication method showed improved detection performance with a 20 dB side-lobe level suppression. The measurement results from the 6-months placements are presented and compared with the state-of the art, revealing that the developed radar is comparable in performance to high-grade automotive radars developed in the industry