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).

Bachelor Theses


Error Propagation of Source coding schemes
lossless source codes are usually variable length codes. Variable length codes, however, suffer from error propagation and synchronization Problems. Consider for example the code: a -> 0 b -> 1 0 c -> 1 1 0 d -> 1 1 1 and the sequence a a b d c a b -> 0, 0,10,111,110,0,10 consider there was a transmission error of bit 4: 0, 0,1111,111,0,0,10 -> a,a,d,d,a,a,b There is error propagation that is however limited. In that thesis we want to investigate this effect
Supervisor: Patrick Schulte

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

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

Bayesian inference and tracking techniques for non-Lorentzian lineshape optical sources

Project description
Research on optical communication systems is nowadays focusing on methods and technologies which would allow higher capacity and increased transmission distance. The capacity of optical communication systems can be increased by a combination of spectrally efficient modulation formats and advanced receiver design. Currently, commercially available optical communication systems employ modulation formats that carry 2 bits/symbol/polarization, such as quadrature phase shift keying. In the near future, it is expected that in order to satisfy capacity demands, it will be required to increase the spectral efficiency to 4 or even 6 bits/symbol/polarization. This would require moving to 16 or 64 quadrature amplitude modulation (QAM).
Moreover, there is a strong focus on designing optical systems with reduced footprint and this requires large scale integration of optical components including semiconductors lasers. The semiconductor lasers exhibit a non-Lorentzian lineshape due to carrier induced frequency noise. This noise presents itself mainly as a resonance peak on the frequency noise power spectral density (PSD), which has been shown to play an important role on the system performance [4]. If phase noise tracking algorithms are not properly designed a large penalty in system performance may be obtained for higher order modulation formats (> 16 QAM) [4-5]. For non-Lorentizan lineshape more sophisticated tracking algorithms are therefore needed as the physics behind the laser phase noise process needs to be taken into account. As a proof-of-principle, it has been demonstrated theoretically and experimentally that Bayesian filtering methods are an effective tool in tracking phase noise that exhibits non-Lorentizan lineshape [5-6]. One of the challenges with Bayesian tracking methods is that they require knowledge of the parameters of the state-space describing the system. This is especially challenging to infer from the measured data due to the high dimensionality of the state-space as well as that the measured systems have typically a large number of unknown variables [7].

Objectives of the project
The main topic of this Master Project is implementation of Bayeisan inference techniques for parameter identification of state-space model for optical sources exhibiting non-Lorentzian lineshapes. The student will develop framework for parameter estimation based on expectation maximization which is an iterative approach for maximum likelihood parameter estimation. The inferred knowledge about the state-space will then be used to formulate digital signal processing algorithms for carrier phase noise compensation for coherent optical communication systems. If time allows, the student will test the framework on experimental data obtained for an optical transmission systems employing long haul transmission and higher order model formats.

Relevant literature
[1] Govind Agrawal, Fibre-optic communication systems, 2010
[2] Dirk van der Borne, PhD Thesis, 2008
[3] Essiambre et al., Journal of Lightwave Technology, vol. 28, 2010
[4] M. Piels, in Proceedings of OFC 2015
[5] L. Barletta, Journal of Lightwave Technology, vol. 30, no. 10, 2012
[6] D. Zibar, Journal of Lightwave Technology, vol. 33, no. 7, 2015
[7] C M. Bishop, Pattern recognition and machine learning, 2006

Supervisor: Luca Barletta, Darko Zibar (DTU)

Modulation and Channel Coding

Scope:I offer master thesis topics in the area of modulation, signaling and channel coding. The goal is to design transmission schemes for reliable communication close to the theoretical limits. We consider wireless, optical and wired communication channels and take power, bandwidth, and latency constraints into account.

Prerequisites: you should have attended one or more of the following courses: Information Theory, Channel Coding, Coded Modulation, Channel Codes for Iterative Decoding.

Start: October 1st.

Supervisor: Georg Böcherer

Ingenieurspraxis


Improving Lab Experiment for Pulse Coded Modulation.
The student will take care of following tasks 1. Modify the Matlab code for PCM lab experiment to make it compatible with the current audio interface. 2. Modernize the Graphical User Interface for the experiment. 3. Improve the description and the assignments for the experiment.
Supervisor: Ali Amjad

Weiterentwicklung des Netzwerkanalyse Tools mit Schwerpunkt auf Testcases
Supervisor: Gerhard Kramer, Fa. Infineon Technologies AG, Neubiberg, Hr. B. Lippmann

Open Student Jobs

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Theses in Progress

Bachelor Theses


Firat Beytemür: Implementation of a ADS-B Receiver

Automatic dependent surveillance-broadcast (ADS-B) is a technology in which an aircraft determines its position via satellite navigation and periodically broadcasts it, enabling it to be tracked. In this work, the student should understand the basics of this technology and implements a receiver to decode ADS-B signals.

ADS-B signals are transmitted over a carrier at 1090MHz with a bandwith of about 50kHz. These signals can be easily received with the software-defined radio (SDR) equipment we have at our institute and can be processed with standard computer equipment. The tasks for this work can be summarized as follows:

  • Understanding the basics of the ADS-B technology.
  • Learning the basics of software-defined radio concept.
  • Baseband processing of the ADS-B signals (estimation, synchronization, etc.)
  • Decoding of the information included in the ADS-B frames.
  • Implementation of a graphical user interface
Supervisor: Onurcan İşcan, Andrei Nedelcu

Arda Can Özensoy: How many cars can YOU park?
Alfred Renyi wrote a curious paper in the late 1950s: He assumed an infinitely parking lane and placed cars, all equally long, randomly on this lane. He found out that you cannot even use 75% of the available parking space [1]!
But I bet you can do better by a more realistic model: Assume cars are between 3 and 6 meters long, and assume that if a car arrives at the parking lane, it will take the first free parking slot (into which it fits). Cars arrive and leave randomly and independently.
The first part of the Bachelor's project is to write a Matlab simulation and determine the efficiency of this parking scheme. Besides some knowledge in Matlab, for this task you should know a little bit about stochastic processes and random variables. The second part involves a literature survey, where you shall find out how this parking/packing problem connects with communications engineering (e.g., code design, communication networks, etc.).

[1]: Renyi's Parking Constant on Wolfram Mathworld (with illustration)
Supervisor: Bernhard Geiger

Stephanie Dangl: A Soft-Information Model for Random Linear Network Coding
Random Linear Network Coding (RLNC) is a powerful approach to achieve the capacity in multicast networks. Subspace codes are an efficient family of error correction codes in RLNC. The idea behind these codes is to map information on a subspace and to transmit a basis for this subspace. In this thesis, a model incorporating soft-information (reliability information) of the received packets (basis vectors) using a linear inner code is considered. First the student should become familiar with linear block codes (e.g BCH, Reed--Solomon codes), concatenated coding schemes and the basics of Generalized Minimum Distance (GMD) decoding. In the next step, suitable inner codes to acquire the reliability information of the received packets should be chosen and implemented in MATLAB. The performance of the coding schemes should be evaluated and compared by performing simulations in MATLAB.
Supervisor: Hannes Bartz, Dr. Vladimir Sidorenko

Franziska Pöller: Hybrid Beamforming for Massive MIMO

Supplying each antenna of a massive IMO base array with an individual radio-frequency (RFC) chain may not be possible due to cost or space constraints. An RFC-chain includes e.g. a digital-to-analog converter and an power amplifier. Hybrid beamforming is a well-known concept which requires less RFC-chains. Digital beamforming with less RFC-chains is followed by analog beamforming. The analog beamforming is realized by phase-shifters, which are cheap compared to full RFC-chains.

The student should implement a an algorithm which determines the hybrid beamforming weights. The optimal number of RFC-chains and phase shifters should be determined. The student may then improve the algorithm.

Supervisor: Stefan Dierks, Markus Jäger

Torsten Ohlenforst: Generierung eines AES67 Audiostreams aus Audiokanälen auf einer Embedded Plattform
Es soll ein Systems aufgebaut werden, mit welchem es möglich ist aus Audiokanälen einen Audio-Stream zu generieren, welcher die Anforderungen von AES67 erfüllt und einen solchen auch wieder in Audiokanäle wandeln kann. Hierzu soll eine Embedded Plattform unter Linux genutzt werden.
Supervisor: Tobias Fehenberger, Dipl.-Ing. Helmut Scholz, Dipl.-Ing. Christian Muschelknautz

Said Ben Bouzid: Antenna Selection in Massve MIMO

Supplying each antenna of a massive MIMO base array with an individual radio-frequency (RF) chain may not be possible due to cost or space constraints. An RF-chain includes e.g. a digital-to-analog converter and an power amplifier. Instead of using all antennas for a transmission it is possible to select a subset of the available antennas so as to reduce the number of radio frequency (RF) chains. This strategy is called antenna selection.

The student should implement an algorithm which determines the set of selected antennas based on information theoretic results. The student should determine the optimal number of RF-chains depending on the channel conditions. The student may extend the algorithm, possibly to a broadcast channel scenario.

Supervisor: Markus Jäger, Stefan Dierks

Master/Diploma Theses


Zhaoqi Zhu: Preamble-based Channel Estimation in Coherent Spatial Division Multiplexing OFDM Transmission System
The robustness of the channel estimation is a key for coherent spatial division multiplexing OFDM transmission system. Time-multiplex(TM) preamble structure has been widely adopted in the polarisation division multiplexing OFDM transmission and in the scenario of spatial division multiplexing OFDM transmission supporting 3 spatial modes. When scaling to higher number of spatial modes, the TM based channel estimation introduces huge overhead and is sensitive to laser phase noise. Therefore, subcarrier-orthogonal(SO) preamble structure is a potential candidate for channel estimation. In this work, the TM and SO preamble-based channel estimation will be investigated under the influence of laser phase noise, mode-dependent loss and strong/weak coupling regime of the few mode fiber.
Supervisor: Yingkan Chen

Stefan Thiel: Analysis of AM Demodulation in Speech-based Airborne Communications Under Multipath Propagation
This master thesis is in cooperation with the radio communications department at Rohde&Schwarz. Airborne radio communication is based on Amplitude Modulation (AM). To use them with existing low-directivity antennas in airplanes, the effects of multipath propagation have to be considered. The student will investigate the channel effects on airborne communications (Ground-Air, Air-Air) and compare possible receiver designs. For this aim, realistic multipath-propagation scenarios will be defined for airborne communications. The models and the suggested designs will be tested with Matlab/Simulink. The student will evaluate the results and compare multiple techniques to improve communication quality.
Supervisor: Onur Günlü, Dipl.-Ing. Ludger Korsmeier and Dipl.-Ing. Michael Gerth (Rohde&Schwarz)

Li Chen: Aggregation Methods for Markov Chains
The purpose of this thesis is to investigate state space aggregation methods using information-theoretic cost function. The main cost functions investigated shall be the I(Y_1;Y_2) and H(Y_2|Y_1) - H(Y_2|X_1). The former, which should be maximized, is related to information-theoretic clustering and to near complete decomposability of Markov chains. The latter, which should be minimized, is related to lumpability, the phenomenon of a function of a Markov chain being Markov. Both cost functions should be optimized over all possible partitions of the state space, which is a combinatorial problem.

In order to reduce the computational complexity of the search, sub-optimal aggregation methods shall be adopted from the literature: Agglomerative, sequential, or splitting methods shall be investigated. Furthermore, it is interesting to see if a relaxation of the cost functions admits the application of established algorithms, like the information bottleneck method.

The aggregation methods shall be evaluated at the hand of a few examples, e.g., quasi-lumpable and nearly completely decomposable Markov chains, examples from natural language processing or synthetic biology, and the Ehrenfest diffusion model.
Supervisor: Bernhard Geiger

QIPING SHAO: OFDM and FBMC
Supervisor: Patrick Schulte

Peihong Yuan: Rate-Matched Coded Modulation for Wireless Transmission
Supervisor: Georg Böcherer, Patrick Schulte, Markus Stinner

Anastasios Dimas: Peeling Decoding Analysis of Non-binary LDPC Codes
The performance of non-binary LDPC (NB-LDPC) codes on the binary erasure channel (BEC) is analyzed. Existing analysis tools of their binary counterparts are extended for NB-LDPC codes. Therefore, the binary extension of the NB-LDPC codes is constructed and its behaviour is investigated analytically.
Supervisor: Markus Stinner

Arun Sattanathan Gothandaraman : Firmware development and testing for Optical communication transceivers
Tasks & Responsibilities: - Architect, design, code, debug, test and document new/existing designs with a major focus on the embedded hardware elements of the design - Work to minimize the need for third party development resources bringing into balance in-house vs. outsourced services - Collaborate with HW designers on the selection of components for new designs where applicable - Develop test procedures and support design of test and design qualification systems- - Provide documentation of all designs
Supervisor: Norbert Hanik, Julio Ramirez (DLR)

Frank Löw: Identification, Development, and Simulation of Protocol Concepts for a Battery-Driven Backbone-Router
The aim of this thesis is to develop low-power protocols for a multi-hop backbone network in a wireless sensor network.
Supervisor: Youlong Wu, Shirin Saeedi, Hekatron Vetriebs GmbH, Philipp Alber

Boxiao Ma: Multipath Assisted Positioning: Mapping of Virtual Transmitters
follows
Supervisor: Norbert Hanik, Christian Gentner (DLR)

Ingenieurspraxis


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

Mahmoud Marcam Helmy: Erstellung einer App für Smartphones der BITS mobile ERP Linie auf Basis von IOS Plattformen
Supervisor: Gerhard Kramer, BITS better it solutions GmbH, Wallenmahd 47, A-6850 Dornbirn

Mohamed Salah Ben Slimen : SDR - Digital Modulation Real Time Receiver in Simulink

Software Defined Radio is a relatively new concept in thinking and designing communications systems. What defines it is that almost all parts of a transciever (transmitter/receiver) are implemented as software modules on a general purpose computer, rather than on dedicated hardware. The radio frequency part of the receiver is thus also reconfigurable through software and will represent just an interface.

Simulink is a graphical programming tool from Mathworks and is especially good for fast prototyping and simulating of complex systems. It provides many custom made software modules and light and easy way to set up graphical user interfaces.

The purpose of this project is that following the principles of SDR radio and the facilities offered by Matlab/Simulink you could build a real-time receiver for digital modulated transmissions. Links:

http://en.wikipedia.org/wiki/Software-defined_radio

http://en.wikipedia.org/wiki/Digital_Audio_Broadcasting

http://de.mathworks.com/products/simulink/

Supervisor: Andrei Nedelcu

Nawel Attia: Nonlinear Error Correction Codes for Erasure Channels: Sudoku
Supervisor: Patrick Schulte

Ulrich Patrick Sandoval: Weiterentwicklung des Netzwerkanalysetools (NAT) mit Schwerpunkt auf Testfälle
Supervisor: Gerhard Kramer, Fa. Infineon Technologies, Neubiberg, Hr. Lippmann

Lei Zhang: Optimierung und Qualitätssicherung des Vodafone GSM-, UMTS- und LTE-Mobilfunknetzes
Supervisor: Norbert Hanik, Fa. Vodafon e GmbH, München, Hr. Quicel

Hasan Yagiz Özkan: Image Tracking Algorithm Development
Supervisor: Gerhard Kramer, Fa. Bases Teknoloji Arge Sanay, Hr. T. Cirak, Istanbul

Burak Tas: Analog- und Digital-Radio: Konzeption und Automatisierung von Testspezifikationen
Supervisor: Gerhard Kramer, Telemotive AG, Breitwiesen, 73347 Mühlhausen

Simon Heine: Softwareentwicklung für Hochfrequenz- und taktische Funkgeräte
Supervisor: Gerhard Kramer, Fa. Rohde & Schwarz GmbH & Co. KG, Mühldorfstr. 15, 81671 München

Jonas Zucker: Kalibrierung/Justage der Ipetronik internen Datenerfassungsmodule
Supervisor: Norbert Hanik, IPETRONIK Eichstätt GmbH, Industriestr. 10, 85072 Eichstätt, Hr. S. Löffler

Ahmet Burakhan Koyuncu: Hardwarenahe Optimierung und Laufzeitverbesserungen der Software, Design und Optimierung von Schnittstellen
Supervisor: Norbert Hanik, MVTec Software GmbH, Neherstr. 1, 81675 München, Hr. T. Hopfner

Forschungspraxis (12 ECTS)


Andreas Lang: Implementing the Split-Step Fourier Method
The Nonlinear Schrödinger Equation (NLSE) is a nonlinear partial differential equation that describes the propagation of light in a nonlinear optical fiber. Since there is no closed-form solution to the NLSE, numerical methods are used to approximately solve it. The most popular among these methods is the split-step Fourier method (SSFM). The student’s task in this Forschungspraxis/Ingenieurspraxis is to implement the SSFM in Matlab-Enabled C (mex) with CUDA support.
Supervisor: Tobias Fehenberger

Mustafa Cemil Coşkun: Staircase Codes for Optical Communications
Staircase codes are a relatively new class of algebraic channel codes for high-speed optical communications. Their large coding gains and reasonable decoding complexity have made them a promising option for data rates of 100 Gbit/s and more. The student's task of this Forschungspraxis is to understand the concept of staircase codes and implement them in Matlab or C.
Supervisor: Tobias Fehenberger, Georg Böcherer