Design and testing of compact dual-band dual-polarized robust satellite navigation antenna arrays

Die steigende Nachfrage nach präzisen Positionierlösungen für hochautomatisiertes Fahren und sicherheitskritische Anwendungen führt zu der Verwendung von Array-basierten Satellitennavigationsempfängern, die aufgrund des verbesserten Diversity-Gewinns und der potentiellen Strahlformungsfähigkeit eine bessere Leistung aufweisen. Die Notwendigkeit, die Robustheit von Navigationsempfängern gegenüber Quellen von Signalstörungen, wie Mehrwegempfang, atmosphärische, sowie Jamming- und Spoofing, zu verbessern, verlangt, den Empfänger weiter auszubauen, um Polarisations- und Frequenz-Diversity auszunutzen. Das hieraus resultierende Design ist durch eine signifikante Zunahme der Hardware- und Softwarekomplexität gekennzeichnet. Diese Komplexität steigt noch mit dem Trend, den Navigationsempfänger zu miniaturisieren, um die Integration in Fahrzeugen oder mobilen Systemen zu erleichtern. Da die gegenseitige Verkopplung zwischen den Antennenelementen eines kompakten Antennen- Arrays steigt, verschlechtert sich deren Strahlungseffizienz und Polarisationsreinheit und damit die Systemrobustheit. In dieser Arbeit wird ein kompaktes, dualbandiges und dualpolarisiertes Antennenarray für einen Navigationsempfänger untersucht, schaltungstechnisch entworfen und aufgebaut, womit Array-, Frequenz-, und Polarisations-Diversity ermöglicht wird. Dies führt zu einer signifikant verbesserten Robustheit gegenüber den angesprochenen Störungen. Diese Arbeit umfasst das Design des dualbandigen und dualpolarisierten Patchantennenelements, das Design des kompakten Antennenarrays, das Studium der Kreuzpolarisationsquellen in Patchantennen, die Analyse des Einflusses der gegenseitigen Kopplung auf die Strahlungseffizienz und Polarisationsreinheit, und die Abschwächung beider Effekte durch eigenmode-basierten Entkopplungs- und Anpassungsnetzwerken. Darüber hinaus beinhaltet die Arbeit die Integration des Antennensystems mit einem HF-Frontend zur Leistungsverstärkung, Filterung und Signalkonvertierung der Satellitensignale. Die Arbeit umfasst auch die Integration mit einem Array-basierten digitalen Empfänger, in dem neben der Datenerfassung, auch die Richtungsschätzung, das Beamforming und die Anti-Jamming-Algorithmen implementiert wurden. Die Machbarkeit sowohl der Array-Diversity als auch der Polarisations-Diversity wurde in Automotive-related Feldmessungen bestätigt, insbesondere für Elevationswinkel unter 40 bzw. 60 Grad, wo der Einfluss des Mehrwegempfangs ausreichend hohe Pegel erreicht. Die Messungen bestätigten die Robustheit des Empfängers gegenüber Stör- Nutzsignalverhältnissen von bis zu 85 dB und übertrafen damit mehrere "State-of-the-Art" Empfänger.The increasing demand for accurate positioning solutions for highly-automated driving and safety-critical applications motivates the use of array-based satellite navigation receivers that feature better performance, due to the enhanced diversity gain and the potential beamforming capability. The need for improving the robustness of navigation receivers against sources of signal distortion such as multipath propagation, atmospheric impact, jamming, and spoofing violations requests to extend the receiver to exploit polarization and frequency diversities. The resulting design is challenged by the significant rise in hardware and software complexity. This complexity increases even more with the trend to miniaturize the navigation receiver, to ease the integration in vehicles or mobile systems, because mutual coupling rises between the radiating elements of the receiver, and deteriorates their radiation efficiencies and polarization purities, and hence degrades the system robustness. In this thesis, a compact dual-band dual-polarized array-based navigation receiver that uses array diversity, frequency diversity, and polarization diversity is studied and designed, to provide robustness against the different types of distortions. The main contributions of the presented work include the design of the dual-band dual-polarized patch antenna element, the design of the compact antenna array, the study of the cross-polarization sources in patch antennas, the analysis of the mutual coupling impact on radiation efficiency and polarization purity of radiating elements, and the mitigation of both impacts using eigenmode-based decoupling and matching networks. Furthermore, the work also involves the integration of the antenna system with an RF-IF front-end, developed in cooperation with IMMS GmbH, for power amplification, filtering, and down-converting. The dissertation covers also the integration with an array-based digital receiver, developed in cooperation with RWTH Aachen University and the German Aerospace Center (DLR), to implement data acquisition, direction-of-arrival estimation, beamforming, and anti-jamming algorithms. The feasibility of both the array diversity and the polarization diversity was confirmed in automotive-related field measurements, particularly for elevations below 40 and 60 degrees, respectively; i.e., at directions far from the main beam direction of the even mode of the array (at zenith), and where the impact of multipath propagation on strength and polarization of the signal reaches sufficient levels to disturb the receiver. Measurements proved the receiver robustness against jamming-to-signal ratios up to 85 dB, outperforming several state-of-the-art receivers described in literature

Wireless communication, sensing, and REM: A security perspective

The diverse requirements of next-generation communication systems necessitate awareness, flexibility, and intelligence as essential building blocks of future wireless networks. The awareness can be obtained from the radio signals in the environment using wireless sensing and radio environment mapping (REM) methods. This is, however, accompanied by threats such as eavesdropping, manipulation, and disruption posed by malicious attackers. To this end, this work analyzes the wireless sensing and radio environment awareness mechanisms, highlighting their vulnerabilities and provides solutions for mitigating them. As an example, the different threats to REM and its consequences in a vehicular communication scenario are described. Furthermore, the use of REM for securing communications is discussed and future directions regarding sensing/REM security are highlighted

Definizione, studio e progetto preliminare di una tecnica di geo-localizzazione di sorgenti interferenti per satelliti commerciali di telecomunicazioni

L’argomento del dottorato riguarda le telecomunicazioni satellitari commerciali. In particolare tratta della possibilità di poter definire, progettare e valutare mediante analisi e simulazioni, un sistema in grado di geo-localizzare sorgenti interferenti nell’area di copertura dell’antenna a bordo satellite per telecomunicazioni (area di servizio). Tale soluzione tecnologica rappresenta un valido supporto per intervenire a seguito di uno o più eventi interferenti. Tale intervento può essere o di tipo passivo, quanto il satellite non è provvisto di sotto-sistema di contromisura, oppure attivo quando il satellite è provvisto a bordo di sistema di contromisura

REDESIGNING THE COUNTER UNMANNED SYSTEMS ARCHITECTURE

Includes supplementary material. Please contact [email protected] for access.When the Islamic State used Unmanned Aerial Vehicles (UAV) to target coalition forces in 2014, the use of UAVs rapidly expanded, giving weak states and non-state actors an asymmetric advantage over their technologically superior foes. This asymmetry led the Department of Defense (DOD) and the Department of Homeland Security (DHS) to spend vast sums of money on counter-unmanned aircraft systems (C-UAS). Despite the market density, many C-UAS technologies use expensive, bulky, and high-power-consuming electronic attack methods for ground-to-air interdiction. This thesis outlines the current technology used for C-UAS and proposes a defense-in-depth framework using airborne C-UAS patrols outfitted with cyber-attack capabilities. Using aerial interdiction, this thesis develops a novel C-UAS device called the Detachable Drone Hijacker—a low-size, weight, and power C-UAS device designed to deliver cyber-attacks against commercial UAVs using the IEEE 802.11 wireless communication specification. The experimentation results show that the Detachable Drone Hijacker, which weighs 400 grams, consumes one Watt of power, and costs $250, can interdict adversarial UAVs with no unintended collateral damage. This thesis recommends that the DOD and DHS incorporates aerial interdiction to support its C-UAS defense-in-depth, using technologies similar to the Detachable Drone Hijacker.DASN-OE, Washington DC, 20310Captain, United States Marine CorpsApproved for public release. Distribution is unlimited

Assessing the Socio-economic Impacts of Secure Texting and Anti-Jamming Technologies in Non-Cooperative Networks

Operating securely over 5G (and legacy) infrastructure is a challenge. In non-cooperative networks, malicious actors may try to decipher, block encrypted messages, or specifically jam wireless radio systems. Such activities can disrupt operations, from causing minor inconvenience, through to fully paralyzing the functionality of critical infrastructure. While technological mitigation measures do exist, there are very few methods capable of assessing the socio-economic impacts from different mitigation strategies. This leads to a lack of robust evidence to inform cost-benefit analysis, and thus support decision makers in industry and government. Consequently, this paper presents two open-source simulation models for assessing the socio-economic impacts of operating in untrusted non-cooperative networks. The first focuses on using multiple non-cooperative networks to transmit a message. The second model simulates a case where a message is converted into alternative plain language to avoid detection, separated into different portions and then transmitted over multiple non-cooperative networks. A probabilistic simulation of the two models is performed for a 15 km by 15 km spatial grid with 5 untrusted non-cooperative networks and intercepting agents. The results are used to estimate economic losses for private, commercial, government and military sectors. The highest probabilistic total losses for military applications include US$300, US$150, and US$75, incurred for a 1, 3 and 5 site multi-transmission approach, respectively, for non-cooperative networks when considering 1,000 texts being sent. These results form a framework for deterministic socio-economic impact analysis of using non-cooperative networks and secure texting as protection against radio network attacks. The simulation data and the open-source codebase is provided for reproducibility

Wireless security for secure facilities

This thesis presents methods for securing a facility that has wireless connectivity. The goal of this research is to develop a solution to securing a facility that utilizes wireless communications. The research will introduce methods to track and locate the position of attackers. This research also introduces the idea of using a Honeynet system for added security. This research uses what is called Defense-In-Depth. Defense-in-depth is when multiple layers of security are used. The first of the layers is the Zone of Interference. This Zone is an area where jammer transmitters and directive antennas are set up to take advantage of the near-far-effect. The idea is to use the near-far-effect to give a stronger signal on the perimeter of the secure area, to mask any signals escaping from the secure area. This Zone uses directive Yagi antenna arrays to direct the radiation. There are multiple jamming methods that are utilized within this Zone. The next layer of security is the Honeynet Zone. The idea is to make an attacker believe that they are seeing real network traffic. This is done at the Honeynet Zone once a device has been determined to be unfriendly. Decoy mobile devices are first placed within the Honeynet Zone. Spoofed traffic is then created between the Honeynet base stations and the decoy mobile devices zone; using adaptive antennas incorporated within the design to face the signals away from the inside secure area. The third defense is position location and tracking. The idea is to have constant tracking of all devices in the area. There are several methods available to locate and track a device that is giving off an RF signal. This thesis looks at combining all these methods into an integrated, and more robust, facility security system

Intelligent-Reflecting-Surface-Assisted UAV Communications for 6G Networks

In 6th-Generation (6G) mobile networks, Intelligent Reflective Surfaces (IRSs) and Unmanned Aerial Vehicles (UAVs) have emerged as promising technologies to address the coverage difficulties and resource constraints faced by terrestrial networks. UAVs, with their mobility and low costs, offer diverse connectivity options for mobile users and a novel deployment paradigm for 6G networks. However, the limited battery capacity of UAVs, dynamic and unpredictable channel environments, and communication resource constraints result in poor performance of traditional UAV-based networks. IRSs can not only reconstruct the wireless environment in a unique way, but also achieve wireless network relay in a cost-effective manner. Hence, it receives significant attention as a promising solution to solve the above challenges. In this article, we conduct a comprehensive survey on IRS-assisted UAV communications for 6G networks. First, primary issues, key technologies, and application scenarios of IRS-assisted UAV communications for 6G networks are introduced. Then, we put forward specific solutions to the issues of IRS-assisted UAV communications. Finally, we discuss some open issues and future research directions to guide researchers in related fields

Reducing Asymmetry in Countering Unmanned Aerial Systems

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumCurrent Counter Unmanned Aerial Systems (C-UAS) rely heavily on low-efficiency techniques such as broadband radio frequency (RF) jamming and high-intensity lasers. Not only do such techniques come at the cost of second and third order effects—such as collateral jamming risks to operational systems, a large RF footprint, and high energy use—but they also present an asymmetry between threat and response. Many commercial, off-the-shelf UAS devices are inexpensive compared to the C-UAS systems historically under focus in Department of Defense (DoD) acquisition. This work argues for leveling that asymmetry by exploring C-UAS autonomy-on-autonomy options by using cyberattack payload capabilities residing on a UAS. By reducing the attack surface to focus on a particular target, these cyber techniques provide scalpel-edged control to the operator, reducing risk to own systems, RF footprint, and collateral damage.Approved for public release; distribution is unlimited

Radio Frequency Interference Impact Assessment on Global Navigation Satellite Systems

The Institute for the Protection and Security of the Citizen of the EC Joint Research Centre (IPSC-JRC) has been mandated to perform a study on the Radio Frequency (RF) threat against telecommunications and ICT control systems. This study is divided into two parts. The rst part concerns the assessment of high energy radio frequency (HERF) threats, where the focus is on the generation of electromagnetic pulses (EMP), the development of corresponding devices and the possible impact on ICT and power distribution systems. The second part of the study concerns radio frequency interference (RFI) with regard to global navigation satellite systems (GNSS). This document contributes to the second part and contains a detailed literature study disclosing the weaknesses of GNSS systems. Whereas the HERF analysis only concerns intentional interference issues, this study on GNSS also takes into account unintentional interference, enlarging the spectrum of plausible interference scenarios.JRC.DG.G.6-Security technology assessmen