Masterarbeiten
Masterarbeiten
- Themenbeschreibung: Spoofing is the transmission of fake Global Navigation Satellite System (GNSS) signals. It is a malicious attack, which misleads a GNSS receiver to calculate the wrong position and time. A receiver, which successfully detects a spoofing event, can warn a user that the position and time cannot be trusted. Therefore, reliable spoofing detection is necessary for GNSS integrity. Previous work on spoofing detection implemented rudimentary machine learning methods. It showed that training on simulated data facilitates good performance when evaluating real recorded data. However, there were several limitations in this study. First, the lack of variance in the real recorded data was insufficient to allow successful training on the data and was adequate to evaluate the data. Second, feature engineering was omitted, and leaves room for improvement. Furthermore, no sufficient studies on the use of deep neural networks have been conducted. This topic aims to improve spoofing detection by advanced machine learning techniques, including feature optimization and deep learning methods. The evaluation is focused on generalization over datasets, reliability and computational complexity.
- Literature review on GNSS, GNSS spoofing, antenna arrays, feature engineering, and supervised machine learning
- Analysis of provided datasets and identification of features
- Identification of suitable machine learning methods (feature based or deep learning)
- Implementation and optimization of the identified machine learning methods
- Evaluation of results
- Documentation of results and final thesis
- Themenbeschreibung: Low earth orbit (LEO) positioning, navigation and timing (PNT) has become a hot topic for satellite?based navigation. LEO mega?constellations, i.e., constellations exceeding 1000 satellites, provide excellent coverage and a good dilution of precision (DOP) for positioning. The much lower altitude – in comparison to medium earth orbit (MEO) or geo?synchronous orbit (GSO) global navigation satellite systems (GNSS) – also provides improved path?loss, yielding better signal to noise ratios (SNRs) for detection, acquisition, and tracking. Furthermore, LEO satellites have high velocity; hence, allowing Doppler?based positioning. Lastly, the LEO constellations selected for PNT are primarily communication satellites, which makes them much less prone to spoofing attacks, in comparison to the predictable GNSS satellites. In conclusion, LEO PNT is a good alternative or complimentary approach to legacy satellite navigation. LEO PNT does have several issues, as these signals are not designed for PNT. First, alternative acquisition and tracking methods are required to extract appropriate observables from the satellites for navigation. Second, these satellites do not necessarily provide their ephemeris information (orbital data) nor are these precise, when they do. Therefore, accurate ephemeris information needs to be estimated. Third, many LEO satellites do not necessarily have a timing reference; hence, this should also be determined. Lastly, LEO satellites rarely have high precision atomic clocks like GNSSs, requiring additional clock corrections. This project focuses on the first challenge, of designing and developing alternative acquisition and tracking methods. As an initial case study, Iridium is proposed. The Iridium downlink is in the 1.6 GHz frequency band, which is adjacent to the L1 GNSS band. Therefore, state?of?the?art GNSS antennas, and modified GNSS recording receivers may be used for a comparable evaluation. Although, Iridium is proposed, the student may identify other suitable LEO constellations and adapt the project accordingly.
- Literature review on GNSS, LEO-PNT methods, and acquisition-tracking methods
- Analysis of opportunistic LEO constellations and selection of a suitable constellation
- Signal recording and analysis of the selected LEO constellation
- Identification of suitable acquisition-tracking architecture and extraction of observables
- Implementation and of an acquisition-tracking architecture to show that a satellite can be used
- Themenbeschreibung: Global Navigation Satellite Systems (GNSSs) provide global positioning capabilities to any capable receiver — whether integrated into smartphones or used for aeronautical navigation. An issue with GNSS signals are their low received signal power on earth’s surface, which makes them sensitive to interference signals. Other licensed spectrum users, the result of old or poorly designed equipment leaking in from adjacent frequency bands, opportunistic use of the spectrum by radio operators, or even purposefully designed interferences, may be the cause interference signals. Therefore, it is crucial for the local service quality to monitor the GNSS frequency bands and to report any interference signal to the appropriate authorities. The DARCY system consists of a network of low-cost sensor nodes to monitor the GNSS spectrum over a larger geographic area. Each node consists of e.g. a Raspberry Pi Single Board Computer (SBC), a low-cost GNSS receiver to monitor the GNSS signal quality, and a Software Defined Receiver (SDR) Frontend to monitor the spectrum. The sensor nodes monitor and report any data to a server, which does interference detection, interference localization, and reporting of any suspicious activity. This master’s project focuses on algorithm development for collaborative interference localization. It uses the DARCY sensor nodes to locate potential interference.
- Literature review on GNSS, interference localization, Received Signal Strength (RSS) positioning, Time Difference of Arrival (TDoA) positioning, collaborative techniques, and information fusion
- Analysis of interference localization methods and data available from the sensor nodes
- Design and implementation of localization algorithm(s)
- Setup of simulation environment to test selected algorithms
- Field recording with interferences and sensor nodes
- Themenbeschreibung: In cooperation with the TU Ilmenau, the Fraunhofer IIS set up a testbed to enable the localization of mobile endpoints using the LPWAN standard mioty for application in current research topics like IoT. The localization is based on time difference of arrival measurements (TDoA).
The mioty standard uses the so-called TSMA (Telegram Splitting Multiple Access) techniques to achieve high robustness against interference. The telegrams consist of single bursts that are pseudo-randomly distributed in frequency and time. However, the long transmission duration of a single telegram (up to 4s) in combination with noisy oscillators can cause severe degradation of the localization accuracy. One way to become more robust against this effect is to adjust the distribution of the individual bursts in time and frequency. In the context of this work, various possibilities are to be investigated as to how this waveform could be modified.
The results achieved in the thesis are to be presented extensively in a written elaboration. The program source code must be sufficiently commented. The DFG rules for good scientific practice are to be respected in the preparation of the thesis. The execution of the work can be done in English as well as in German language.
In detail, the tasks mentioned above are to be conducted:
- Literature research on the principle of TDoA localization and Phase noise and on the mioty standard according to ETSI TS 103 357
- Familiarization with the existing simulation framework
- Optimization and modification of the existing waveform
- Conducting simulations with the adapted waveforms and compare the results to the standard waveform
- Verification of the results in real-world measurements
- Themenbeschreibung: The study of radar targets and their electromagnetic wave reflectivity models holds paramount importance in radar simulations. Traditionally, radar scenarios have operated under the assumption that the echo component is narrower than the radar resolution, allowing for the modeling of reflectivity as point scatter. However, with the current evolution of modern radar systems, such as Integrated Sensing and Communication (ISAC), i.e. for intelligent transportation and surveillance, this assumption no longer holds. ISAC systems feature higher resolution in range, Doppler, and angle observations than the extension of echo-pattern, particularly in scenarios involving larger targets such as cars or unmanned aerial vehicles (UAVs). This necessitates the development of new reflectivity models capable of accurately capturing the characteristics of extended echo patterns, including consideration for micro-Doppler effects. This thesis seeks to address this critical research gap by proposing novel reflectivity modeling approaches for extended echo patterns for radar targets. By investigating and developing these models, we aim to enhance the realism and accuracy of radar simulations in ISAC scenarios. - Literature review on reflectivity models and radar cross section (RCS) for extended targets. - Identify the analytical and computational requirements for reflectivity models of extended targets. - Identification of suitable modeling approaches - Implementation and development of new reflectivity models - Evaluation of results - Documentation of results and final thesis The results achieved in the thesis are to be presented extensively in a written elaboration. The program source code must be sufficiently commented. The DFG rules for good scientific practice are to be respected in the preparation of the thesis. The execution of the work can be done in English as well as in German language.
- Themengebiete:
- Voraussetzungen:
- Betreuer: Carsten Smeenk
- Hochschullehrer: Prof. Albert Heuberger
- Themenbeschreibung: Backscatter-Kommunikation ist eine Technik, die es Geräten ermöglicht, zu kommunizieren, indem sie externe Funksignale reflektieren und modulieren, wodurch nur sehr wenig Energie für die Übertragung benötigt wird. Dieser Ansatz ermöglicht eine extrem energie-sparsame drahtlose Kommunikation für IoT und Sensornetzwerke, was entscheidend ist, um den Energieverbrauch von Funkknoten zu minimieren und ihren die Lebensdauer zu verlängern.
Aktuell ist dieser Ansatz ein relevantes Thema in der Funk-Standardisierung. Es wird sowohl in 3GPP zur Aufnahme in den 5G-Standard über das „Ambient IoT“ Study Item diskutiert, als auch in IEEE für den WLAN-Standard innerhalb der Ambient Power (AMP) Technical Interest Group.
In der Abteilung Energieautarke Funksysteme des Fraunhofer IIS wird Backscatter-Kommunikation mit besonderem Fokus auf dem Ansatz der Ambient-Backscatter-Kommunikation erforscht. Hier werden Signale von TV, Radio und Mobilfunknetzen für die Datenübertragung genutzt, was nicht nur den Funkknoten extrem energiesparend macht, sondern auch die Erzeugung eines Backscatter-Träger-Signals wie bei konventioneller Backscatter-Übertragung (beispielsweise bei RFID Sytemen) einspart.
Im Rahmen einer Bachelor- oder Masterarbeit soll hierfür ein Demonstrator aufgebaut werden, bei dem ein per Energy-Harvesting mit Energie versorgter Sensorknoten per Funk nach dem Ambient-Backscatter-Prinzip Daten überträgt.
Die Arbeit umfasst folgende Punkte: - Vergleich verschiedener Energy-Harvesting-Quellen - Entwicklung eines energiesparsamen Hardware-Konzepts, ggf. Messtechnische Prüfung einzelner Umsetzungskonzepte - Entwicklung Umsetzung Hardware-Konzept des Knotens auf einer Platine - Inbetriebnahme, Evaluierung und Optimierung der Platine.
Die im Rahmen der Arbeit erzielten Ergebnisse sollen im Rahmen einer schriftlichen Ausarbeitung umfangreich dargestellt werden. Erstellter Programmquellcode ist ausreichend zu kommentieren. Bei der Erstellung der Arbeit sind die DFG-Regeln zur guten Wissenschaftlichen Praxis einzuhalten.
- Themengebiete:
- Voraussetzungen:
- Betreuer: Clemens Korn
- Hochschullehrer: Prof. Albert Heuberger
Anfragen zu Themen und der Betreuung einer MA-Arbeit können sie auch unabhängig von den ausgeschriebenen Themen direkt an die Ansprechpartner der jeweiligen Forschungsschwerpunkte schicken.
Telemetrie
Satellitenkommunikation
Navigation und Ortsbestimmung / GPS und Allg.
