Persönlicher Status und Werkzeuge

Open Theses

You may also contact one of our doctoral candidates directly, if you are interested in a Bachelor or Master thesis, a student job, an "Ingenieurspraxis" or a "Forschungspraxis". It often happens, that topics are being prepared which are not adverdised yet. It may also be possible to find a topic matching your specific interests.
Please include a curriculum vitae together with a list of attended courses when applying for a thesis.
If your "Ingenieurspraxis" is selected to be supervised by one of our professors, please hand in the documents to Doris Dorn (Room N2401).

Master/Diploma Theses


A Deterministic Approach to the Gaussian Multiple-Input Multiple-Output (MIMO) Broadcast Channel
Multi-user communication systems (such as wireless systems) are different than point to point channels in two key aspects; namely, the broadcast nature of transmissions (e.g., wireless transmissions can be picked up by any receiver in the vicinity of the transmitter) and the superposition (e.g., a wireless receiver picks up a linear combination of transmissions from all transmitters in its vicinity). Recently a deterministic approach to multi-user information theory has proved promising by achieving progress in some of the long-standing open problems by finding approximate solutions. The idea behind a deterministic approach, on a high level, is to focus on the interaction of signals rather than the background noise, through a simpler appropriate model; find exact solutions for the simpler model; and then translate the intuitions and techniques to new techniques and/or approximate solutions on noisy models.
The goal of thesis is to undertake a deterministic approach to Gaussian MIMO broadcast channels.
Prerequisite: Linear Algebra, Information Theory
Supervisor: Shirin Saeedi

Achievable Rate Regions for Multiple Access Relay Channels with Relay-source Feedback using Quantize-forward
Description

The multiple access relay channel (MARC) is an important model in cooperative communications since it captures both broadcast and multi-access.
Traditionally only information flow in one direction was considered, namely from the sources to the destination. We would like to extend this model by incorporating information flow (feedback) from the relay to the sources.
In previous work, we studied MARC with feedback using decode-forward (DF) and showed that feedback did increase capacity region of the MARC without feedback. We would like now to study MARC with feedback using compress-forward (CF) or quantize-forward (QF) to see whether one can get larger rate gains. The tasks of the thesis are:

1. Understand random coding arguments for the MARC with/without feedback using DF and the analysis for achievable rates.
2. Design achievability schemes for MARC using QF or CF and find the achievable rates. Compare the rates with QF and CF. Are they the same? If not, justify the difference.
3. Do the rates vary with the geometry of the network ? For example, if the relay is closer to the sources and far from the destination, is DF or QF the better choice? For a fixed coding scheme, e.g., QF, where should we place to the relay so that the rates are maximized?
4. Our initial assumption is that the feedback link is noise free. How would the coding scheme change if the feedback is noisy?
5. Use numerical simulations to back up the theories derived above.

Requirements
Information Theory is a MUST.
Multi-User Information Theory is a PLUS.

Reference
[1] J. Hou, R. Koetter and G. Kramer. Rate regions for multiple access relay channels with relay-source feedback. IEEE Information Theory Workshop (ITW) 2009, Oct. 2009.
[2] T. Cover and A. E. Gamal. Capacity theorems for the relay channel. IEEE Trans. Inf. Theory, 25(5):572–584, Sept. 1979.
[3] G. Kramer and A. van Wijngaarden. On the white gaussian multiple- access relay channel. IEEE Int. Symp. Inf.Theory, page 40, Sorrento, Italy, June 2000.
Supervisor: Jie Hou

Role of Feedback in Broadcasting
This project intends to investigate the role of feedback in broadcast channels. More information available upon request. Pre-requisite (at least one of the following):
Basic knowledge of Network Coding (see [2])
Basic knowledge of Algorithms
Basic knowledge of Information Theory
Supervisor: Shirin Saeedi

Powerline Communication for industrial application
Powerline Communication (PLC) is a well established technology for in-building data transmission. The HomePlug standard provides an easy to use interface. PLC is charackterized by modulation and coding schemes which ensure robustness against impuslsive noise and disruptions by the power transmission and transformation. Hence, the PLc becomes an interesting approach for industrial applications such as power charging stations for electrical cars or in the field of smart grid. This Master thesis shoudl analyze the PLC technology on the basis of the HomePlug Greenphy standard and its realization in todays chipsets. In particular, the optimization of the given PLC realizations for industrial use will be the focus of this work. This MAster thesis will be done in cooperation with Siemens AG Corporate Technology.
Supervisor: Elisabeth Georg

Open Student Jobs

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Theses in Progress

Bachelor Theses


Alexis Gonzalez-Argüello: Development of a Computer Implementation of Computational Methods for Time-harmonic Electromagnetic Field Modeling
Supervisor: Gerhard Kramer, Stellenbosch-University, South Africa, Prof. M. Botha

Stephanie Rupp: Error Correction for Bluetooth Low Energy
Up to now, the Bluetooth Low Energy standard does not define any error correction. During the initialization of the connection, the power consumption due to lost packages could be lowered using error correction. Therefore, the possible energy savings using error correction schemes shall be investigated. Various error correction schemes shall be designed and tested by simulation.
Supervisor: Markus Stinner, Hannes Bartz

Niklas Jünger: User Selection and Scheduling in the Massive MIMO Broadcast Channel

In MIMO OFDM systems the base station schedules transmissions to a group of users in one resource. We use transmit precoding with a zero forcing objective to cancel interference and decompose the MIMO channel into interference-free parallel channels. The gain of these parallel channels depends on the choice and number of users scheduled in the resource. The goal is to find a user grouping and scheduling such that an objective function is optimized. The optimal constellation can usually only be found by exhaustive search. Existing heuristic algorithms are evaluated and improved.

Supervisor: Stefan Dierks

Edvarts Berzs: Sum-Rate Maximization with Leakage-based Coordinated Scheduling Strategies

We consider a cellular communication system with single antenna base stations and user equipment. Each base station transmits to its users using OFDMA. Interference from the other cells is treated as noise. The base stations are allowed to cooperate when determining the transmission schedule. The goal is to find a schedule such that an objective funtion optimized. The optimal schedule can usually only be found by exhaustive search. Existing heuristic algorithms are evaluated and improved.

Supervisor: Stefan Dierks

Diego Lentner: Blind Mutual Information Estimation Techniques
Mutual Information (MI) is a key quantity of information theory as it is the achievable rate of transmission. Estimating MI can be a challenging task for a channel whose transition probabilities are unknown, such as the optical channel. Different estimation techniques, including histograms and kernel density estimators, are investigated for rectangular quadrature amplitude modulation over an additive white Gaussian noise channel with varying signal-to-noise ratio.
Supervisor: Tobias Fehenberger

Alexander Domanski: Digital Baseband Transmission in SimuLink
A basic digital baseband transmission shall be implemented in SimuLink showing the influence of channel equalization, filters and the choice of the receiver. The focus is especially on the comparison of adaptive equalization techniques. The aim is to obtain an implementation which can also be used as a platform for a lab experiment. Parts of the bachelor thesis will be used for the description of this experiment.
Supervisor: Markus Stinner

Master/Diploma Theses


Jiajing Niu: Optimization of Dispersion Maps for Coherent Optical Communication Systems
The vast majority of internet traffic is transferred over optical fibers that are subject to various kinds of distortions. Dispersion, which is a linear effect describing how the propagation speed of light in matter depends on its wavelength, can be dealt with either using dispersion compensation fibers (DCFs) or electronically in the digital signal processor (DSP). Some medium-reach networks still have DCFs deployed instead of relying on DSP compensation. By suitably choosing how much dispersion is compensated optically at which stage of the link, the overall system performance can be increased. Also, the gap to electronic compensation can be reduced.
Supervisor: Tobias Fehenberger

Patrick Schulte: Density Bending
Development and analysis of a practical zero-error, block-to-block distribution matcher that can be used for probabilistic shaping in digital communication systems.
Supervisor: Georg Böcherer

Marcin Pikus: Communication over the Rayleigh block fading channel
The goal of the project is to design a low complexity communication scheme that operates close to the theoretic limits.
Supervisor: Georg Böcherer

Julian Schiele: Development of a Framework for Fourier-Motzkin Elimination regarding Applications in Network Information Theory and Index Coding
Index coding is a special case of network coding and is interesting because of increasing demand for efficient wireless communication, e.g., video-on-demand applications. The index coding problem deals with communication scenarios where one sender wants to transmit N messages to N receivers over a single common link with presense of priori side information at the receivers. The aim is to minimize the number of transmissions while satisfying the communication requirements. We consider this problem because any instance of a network coding problem can be reduced to a index coding problem. Although the capacity region of a general index coding problem is not known, some inner bounds are developed using composite coding. However there is a large number of rate bounds involved. Thus, we use Fourier-Motzkin elimina- tion on the composite indices, which eliminates variables from a system of inequalities, to simplify the rate bounds. In this thesis, Fourier-Motzkin elimination is analyzed as a method to simplify groups of inequalities and a systematic framework is developed to tackle significant network information theory problems. The results developed will be applied to index coding problems to reduce the number of bounds involved. For this purpose, theory on polytopes and information inequalities will be studied.
Supervisor: Jie Hou, Ali Amjad, Prof. Young-Han Kim

Mahdy Shabeeb: Optimization and Algorithm Design in 5G Nomadic Relay Networks
In this master thesis, the optimization algorithm and performance evaluation of nomadic relay network will be investigated. Nomadic Relay (NR) in 5G refers to the approach by using parked vehicles as potential relaying candidates, to provide coverage expansion, capacity enhancement, or to increase energy efficiency. Compared with fixed relays, NRs are randomly distributed and are dynamically changing locations. Therefore, relay selection and activation is a key technique to provide reliable performance improvements. Based on the previous optimization framework, more practical scenarios will be investigated in the thesis, including directional antenna configuration at the base stations, smart antenna designs for vehicles and in- und out band relaying options. Another important aspect is to analyze the impact of the dynamic behavior of NRs on the interference structure and hence on the network performance. The optimization objective is first the network energy efficiency, followed by a generalization onto a load balancing approach.
Supervisor: Michael Heindlmaier, Dr. Peter Fertl, Ren Zhe (BMW Forschung und Technik)

Markus Jäger: Advanced Concept for enhancing Nomadic Relay Network Performance in 5G systems
In this master thesis, the power control algorithms jointly with advanced relay concept will be investigated in the context of nomadic relay network for reliably expanding coverage and improving system capacity. Nomadic Relay (NR) in 5G refers to the approach by using parked vehicles as potential relaying candidates, to provide coverage expansion, capacity enhancement, or to increase energy efficiency. Due to the randomness of NR distributions, dynamic power control is an essential technique for relay activation without generating fatal interference to the other users in the network. Based on the previous framework, distributed power control schemes (comprises the power control of both relay backhaul link and access link) of nomadic relay network will be combined with user assignment for coverage optimization. The goal is to activate relays and handover users, whereas the SINR requirements of all the users are not violated. Furthermore, advanced cooperative relaying schemes will be evaluated jointly with the power control algorithms to further optimize the coverage and capacity, under the constraints of user QoS and network energy consumption.
Supervisor: Michael Heindlmaier, Dr. Peter Fertl, Ren Zhe (BMW Forschung und Technik)

Tasnad Kernetzky: Powerline Communications for Industrial Applications
Insbesondere im Heimumfeld hat sich die Powerline Kommunikation, basierend auf dem Homeplug Standard, etabliert und wird zunehmend eingesetzt. Wichtig für die Powerline Kommunikation ist, dass die eingesetzten Modulations- und Kanalcodierungsverfahren robust gegenüber Störungen sind, die bei der Leistungsübertragung und Energiewandlung auftreten und auf das übertragene Signal überkoppeln. Dies macht diese Verfahren auch interessant für den industriellen Einsatz. So werden Powerline Kommunikationsverfahren beispielsweise bei der Ladekommunikation für Elektrofahrzeug oder im Bereich des Smart Grid eingesetzt. In der Masterarbeit soll zunächst die Powerline Kommunikation nach dem Standard HomePlug Greenphy und deren Umsetzung in heute verfügbaren Chipsätzen analysiert werden. Darauf aufbauend sollen Optimierungsmöglichkeiten der Powerline Kommunikation z. B. bezüglich des gewählten Modulationsverfahrens, der Signalentzerrung, einer eventuellen Leitungscodierung, der eingesetzten Forward-Error Correction, für die Anwendung im industriellen Einsatz unter Kenntnis der Umsetzungen in diesen Chipsätzen erarbeitet und bewertet werden. Die Masterarbeit wird in Zusammenarbeit mit der zentralen Forschung der Siemens AG Corporate Technology durchgeführt.
Supervisor: Norbert Hanik, Anton Schmitt, Siemens

Arthur Smolorz: Using GPS for Channel Measurements
For modern wireless communication systems as well as for satellite navigation receiver knowledge about the wireless channel is essential. A more detailed knowledge of wave propagation enables an increase in data throughput as well as a higher accuracy of positioning systems by making use of channel characteristics. As computer models and simulation still incur a high computational burden or suffer from lack of detail in modelling the environment, channel measurements are still needed and are an essential tool to gain knowledge about wave propagation. In recent years the number of applications using the Global Positioning System (GPS) for positioning is increasing steadily. The system itself provides satellites in orbit transmitting a periodic signal at large bandwidth. For precise localisation of the user, the position of the satellites as well as their time synchronisation must be known. Using the satellites’ signals for channel measurement applications seems to be ideal. The major drawback to do so is the low received signal power such that paths might not be detected. Averaging in static scenarios can increase the Signal to Noise Ratio (SNR) up to a level that all features of the propagation channel are visible. In a non-static scenario with a moving receiver pure averaging is disadvantageous due to the time varying phase of a path’s complex amplitude. Hence, estimation algorithms, so called super-resolution methods, are applied to cope with the non-stationary of the channel by using a model which includes the movement. To the end, a representative data-set of GPS signals shall be recorded and channel related features extracted using a sequential Bayesian filter algorithm. To solve these tasks, the student has to acquire understanding of GPS, wave propagation and signal processing.
Supervisor: Andrei Nedelcu, Dr. Thomas Jost (DLR)

Prashanth Raju: Design of Real-Time Demodulation of Analog and Digital Modulated Signals in a Time- domain EMI Measurement System and Evaluation to EMI Signals
Design of Analog and Digital demodulation schemes for FPGA hardware and integration into a existing EMI time domain measurement system. Validation and verification of design pre and post implementation.
Supervisor: Andrei Nedelcu, Dr.-Ing. Stephan Braun, Dipl.-Ing. Arnd Frech

Neha Baheti: Adaptive Beamforming for Massive-MIMO in Next Generation Wireless Networks

Multiple-input-multiple-output (MIMO) techniques provide the possibility of serving multiple users simultaneously with the same resources by proper precoding of the spatially separated streams. This Master Thesis investigates adaptive beamforming concepts for large scale arrays in wireless communications. The scope is to implement adaptive multiuser downlink beamforming by designing a proper precoding scheme. The precoder can be obtained by complex optimization, i.e. the optimal beampattern to multiple users is to be generated to obtain the required SINR at the terminals of the users by using the minimal possible transmit power constrained by the interferers in the angular domain. The adaptive beamforming technique is scenario specific and shall mitigate intra-cell interference as well as inter-cell interference.

In the framework of the thesis a beamforming precoder for the above scenario is to be implemented and tested in a multi-user scenario.

Supervisor: Andrei Nedelcu, Stefan Dierks, Berthold Panzner (Nokia Solutions and Networks)

Tobias Fülle: Preamble recognition on NC-OFDM modulation for dynamic synchronization
Within a public subsidized research project called COUWBAT, the student will develop a combined ultra-wide band and cognitive radio HW-Transceiver to increase the spectrum efficiency and data rates through the utilization of the so-called white spaces for secondary users. Therefore, the NC-OFDM method will be applied to switch certain subcarriers on and off. Later on, evaluation of FilterBank Multicarrier (FBMC) is aimed to take place.
Supervisor: Onur Günlü, Manuel Sáez Rodríguez

Ingenieurspraxis


Robert Fellendorf: Untersuchung der HF-Parameter für die Eignung zum Einsatz in IM-Messgeräten
Supervisor: Gerhard Kramer, Fa. Rosenberger, Hochfrequenztechnik GmbH & Co. KG, 83413 Fridolfing

Eghbal Darius Ketabtchi: Techn. Support und Kundenservice im Bereich IPTV und Durchführung von Produkttests mit Dokumentation
Supervisor: Gerhard Kramer, Fa. TERACUE AG, Schlossstr. 18, Odelzhausen, M. Schönberger

Shu Liu: Aufbau eines Evaluationsboards mit Vermessung durch einen Multiport-Netzwerk-Analyser
Supervisor: Norbert Hanik, Infineon Technologies AG, IFAG HR BPS SD, 85579 Neubiberg, Hr. R. Kuhn

Dominik Fienko: Integration BS2000 SE Serie in Enterprise System Management
Supervisor: Gerhard Kramer, Fa. Fujitsu Technology Solutions, PDG ES S SWE 057, München

Sebastian Requena-Witzig: Recherche und Entwicklung von Umsetzungskonzepten für Fahrerassistenzsysteme basierend auf Radar- und C2X-Daten
Supervisor: Norbert Hanik, Fa. Fraunhofer ESK

Julian Leyh: Bearbeitung und Erweiterung von FPGA-Komponenten für IP-Paketverarbeitung
Supervisor: Gerhard Kramer, Fa. Rohde & Schwarz GmbH & Co. KG

Daniel Klimsa: Wahrscheinlichkeitsbewertung bei Mehrfachtreffern
Supervisor: Norbert Hanik, Siemens AG, Dr. Blume

Linus Reitmayr: Testmanagement FDDB
Supervisor: Norbert Hanik, BRAIN GmbH, 80809 München

Forschungspraxis (12 ECTS)


Dietrich Dumler: GPS/Galileo data reception
The ways to use Software Defined Radio (SDR) equipments to receive and decode GPS and/or Galileo signals are tested. The first part of the internship consists of searching for already existing codes that can be used with our SDR equipments. Later, offline CDMA decoding and synchronization algorithms will be analyzed and parametrized to understand the effect of different techniques.
Supervisor: Onur Günlü