For quick reference, we show the RECAP structure. The channel measurement data was obtained by using a 5 × 5 RECAP array at Alice, with a center feed element (in orange) and 24 other parasitic half-wave dipole antennas spaced λ/4 apart. The 24 parasitic dipoles are reconfigurable elements loaded with electrically tunable capacitances. The active
Starting from obvious similarities in operations in LDPC decoding to common neuron models, we have started making this correspondence more obvious. There are manifold possibilities to bridge the two fields, where some applications like denoising offer very obvious links, others appear much more distant.
Student: Ahmed Elshahed Advisor: Prof. Dr.-Ing. Werner Henkel Dr. Khodr Saaifan Time frame: Spring 2016 Description: In this thesis, we consider the interference cancellation problem for the broadband digital aeronautical communication system. We investigate the L-band digital aeronautical communication system (L-DACS) in the presence of distance measuring equipment (DME) interference. First,
Student: Yilun Zhang Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2016 Description: With increasing significance of wireless transmission, physical layer security becomes a challenging topic resulting from the Shannon’s limit. This work explores physical layer security from the aspect of information theory and discusses key generation and reconciliation by Slepian-Wolf coding and low-density
Student: Sudipta Basak Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2017 Description: The purpose of this research is to primarily focus on investigating channel reciprocity in power lines. Initially, we will conduct experiments to determine the properties of the power line channel from both the transmitter side
Student: Navdeep Manak Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2017 Description:
Student: Monder Hamruni Advisor: Prof. Dr.-Ing. Werner Henkel Oana Graur Time frame: Spring 2017 Description: The properties of the physical layer in wireless networks are exploited to generate one-time pads which are subsequently used for secure communication between legitimate users. Previous measurements testbeds relied mostly on RSSI information, since
Student: Usama Nadeem Advisor: Prof. Dr.-Ing. Werner Henkel Dawit Nigatu Time frame: Spring 2016 Description: Bidirectional reading processes have been recently incorporated into the Lempel-Ziv family of lossless compression algorithms namely LZ-77, LZ-78 and LZW 84. Bidirectional compression results in better compression ratios especially if the uncompressed data contains symmetric properties. In this work
Student: Etta Shyti Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2016 Description: All the work in this bachelors thesis is focused on investigating channel reciprocity in powerlines, i.e. performing measurements, which determine channel properties as seen from both the transmitting and receiving side, followed by a comparison and analysis of results.
Student: Kristi Gadeshi Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2016 Description: The purpose of this research is the investigation and understanding of a security technique in wireless communications based on physical attributes of the channel. We consider a scenario where a communication channel is set up between two
Student: Alban Sherifaj Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2016 Description: We investigate the possibility of using physical layer security as a new mean of securing data during transmission. We particularly look into the identification of the Direction of Arrival of reflection patterns in a NLOS channels as
In contrast to the the well-known separation theorem, in the non-asymptotic regime, joint source-channel coding can have advantages. We design multi-edge-type LDPC codes for different source statistics.
Student: Robin Nyombi Schofield Ssenyonga Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2015 Description: Neural network rules and coding theory concepts have been associated in the past. It is known that in relation to neural networks, iterative decoding exhibits some nonlinear dynamics. The purpose of this thesis, therefore, is
Student: Zinan Liu Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2015 Description: This Guided Research focuses on frame synchronization for the DMT-based transmission system, which is used on a proposed acoustic sensor network for sonar applications. The time offset estimate not only needs to be robust and accurate to
Student: Riwaj Sapkota Advisor: Prof. Dr.-Ing. Werner Henkel Oana Graur Time frame: Fall 2012 Description: The objective in this project was to build a network topology along with the loss rate stated for each link which shall later be used to evaluate and analyze self-proposed network coding strategies. During the project,
Student: Riwaj Sapkota Advisor: Prof. Dr.-Ing. Werner Henkel Oana Graur Time frame: Fall 2012 Description: Erasures in communication channels play an important role in data transmission in real networks. It has also been well establised that linear network coding is enough to achieve the upper bound in multicast problems. In this
Student: Nazia Sarwat Islam Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2014 Description: Physical-layer security options can provide robust security measures in a wireless scenario and is a topic of current interest. In this work, we consider a wireless, reciprocal channel between two legitimate users and assume a frequent physical-layer key generation
Student: Ahsan Javed Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2013 Description: Key reconciliation techniques are employed to discard the effect of uncorrelated noise present at the communicating nodes of a reciprocal channel. Under a direct line-of-sight scenario, to randomize the channel, one of the communicating nodes shall be equipped
As an alternative to Diffie Hellman’s key exchange protocol, physical layer key generation is discussed based on measurements of reciprocal channels. Due to statistically independent noise together with vector quantization, the keys might not be the same. Hence, the contribution discussed key reconciliation possibilities, either introducing guard bands or LDPC Slepian‐Wolf coding. We derive a
Student: Alexandra Filip Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2012 Description: Key reconciliation procedures are needed to correct key differences that can arise as a consequence of independent noise at the two ends of a reciprocal link. We assume a line-of-sight channel and use reconfigurable antenna elements to randomize
Student: Alexandra Filip Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2012 Description: Physical-layer key generation makes use of the reciprocity of wireless time-division duplex (TDD) channels. Both transmission directions experience the same channel, apart from independent noise and quantization effects. The randomness of a mobile channel ensures a certain regeneration
Student: Alexandra Filip Advisor: Prof. Dr.-Ing. Werner Henkel, Dr. Mathias Bode Time frame: Spring 2013 Description: Physical-layer security in wireless communication is a challenging topic needed to allow for secure and reliable information transfer, otherwise subject to eavesdropping. In particular, physical-layer key generation methods use the properties of the channel itself
Student: Alexandra Filip Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2011 Description: We propose a linear programming approach to optimize the variable node degree distribution for a Low-Density Parity-Check code that will provide UEP inside a modulation symbol. Based on a rate maximization criterion, the optimization of the degree distribution
Student: Nazia Sarwat Islam Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2013 Description: LZ77, LZ78, and LZW84 are universal lossless data compression algorithms for reducing redundancy. A modiﬁed version of these algorithms that takes into account both forward and reverse readings is presented in this work. It is shown
Student: Dawit Andualem Nigatu Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2013 Description: In the previous project, we used classical multidimensional scaling (CMD) to scale down the 64 x 64 ECM mutation matrix and 20 x 20 amino acid chemical distance matrix to 2 dimensions (2-D). From the 2-D representations,
Student: Dawit Andualem Nigatu Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2013 Description: This research contains two separate parts. In the first part, we have used classical multidimensional scaling (CMD) technique to scale down a 64-dimensional empirical codon mutation (ECM) matrix and a 20-dimensional chemical distance matrix to two dimensions
Student: D. Thejani Himalika Fernando Advisor: Prof. Dr.-Ing. Werner Henkel Oana Graur Time frame: Spring 2013 Description: In this research, we have investigated the performance of using an adaptive NLMS filter to cancel impulse noise on powerlines. Using 930 impulses from various sources, which had measured and collected between the live-neutral
Student: Thejani Himalika Fernando Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2012 Description: We designed and constructed a suitable circuit for detecting and measuring the power line impulse noise which appears between live and neutral lines as well as between neutral and earth lines. Our study also involved in measuring
Student: Mohammad Ismail Hossain Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2011 Description: We address noise which is impulsive, non-Gaussian, and follows a heavy-tailed distribution. In wireless communications, often noise is considered as an additive white Gaussian noise (AWGN). In reality, receivers have omnidirectional capability and it receives many signals
Student: Asif Ahmed Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2011 Description: The project had to aspects. We carried out first multi-antenna measurements of impulse noise in the 2.4 GHz range caused by car ignition and other sources. Additionally, a new circuit was design for wirelines impulse-noise measurements in common
Student: Maja Taseska Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2010 Description: The combination of multicarrier modulation (OFDM, DMT) and Multiple- Input Multiple-Output (MIMO) transmission significantly improves the quality and efficiency of modern communication systems. The peak-toaverage ratio problem in multicarrier modulation requires additional transmitter side processing which may get
Student: Osama Furqan Khan Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2010 Description: In contemporary communication systems, Turbo coding is an important channel coding method which results in extremely low bit-error ratios (BER) at signal-tonoise ratios (SNRs) within 1 dB off the Shannon Limit. The BCJR algorithm is used as
Student: Jalal Etesami Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2013 Description: Lattice Codes show good performance and can approach the capacity of additive white Gaussian noise channel. In the Lattice Codes a codeword x is generated by a linear transformation of corresponding integer message vector d, i.e., x =GTd, where G
Student: Oana Graur Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2009 Description: Impulse noise has long been known for causing transmission errors. The current thesis presents a method of mitigating impulse noise using a Normalized LMS canceler which takes as reference input the common mode signal and subtracts the adapted
Student: Ina Kodrasi Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2008 Description: This report studies the encoding of Reed-Solomon codes with consecutive time and DFT domain redundancy. Many data transmission schemes rely on Reed-Solomon codes for error correction, therefore a thorough comprehension of their properties would be very constructive. An
Student: Jalal Etesami Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2008 Description: We introduce a new algorithm for constructing LDPC codes based on a Protograph. With Protographs, we have a base graph (mother graph), which is duplicated a number of times followed by a special edge permutation obtaining the largest
Student: Abdul Wakeel Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2008 Description: RS codes can be defined using a DFT matrix which is known to diagonolize a Toeplitz matrix. This property is commonly used in multi-carrier modulation, since the channel realises a convolution which can be represented by a Toeplitz
Student: Guftaar Ahmad Sardar Sidhu Advisor: Prof. Dr.-Ing. Werner Henkel, Khaled Shawky Hassan Time frame: Fall 2008 Description: In this work we look into the problem of inter-user interference in multiuser MIMO systems. We disscuss two different SDMA MIMO schemes. The first scheme, the orthogonal SDMA, completely eliminates the inter-user interferance. It
Student: Guftaar Ahmad Sardar Sidhu Advisor: Prof. Dr.-Ing. Werner Henkel, Khaled Shawky Hassan Time frame: Spring 2008 Description: In this work, we consider the downlink transmission of a multiuser system. Both the Single Input Single Output (SISO) and Multiple Input Multiple Output (MIMO) antenna systems between the base station (BS) and the
Student: David Kronmüller Advisor: Prof. Dr.-Ing. Werner Henkel, Neele von Deetzen Time frame: Spring 2008 Description: The demand for higher communication data rates is immense in the era of high quality multimedia content. The issue at hand is to increase data transfer rates while improving error tolerance lev- els. Turbo codes
Student: Behrouz Touri Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2008 Description: Binary linear codes are one of the main tools for error-control coding over telecommunication channels and data storage devices. However, despite of having very simple encoder structures, their optimum decoding is usually a hard problem in practice. In
Student: Karim Ibrahim Khashaba Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2007 Description: This thesis examines the benefits of using adaptive modulation in terms of bit error probability. Specifically, we examine the performance enhancement made possible by using linear prediction along with channel estimation in conjunction with adaptive modulation. We
Student: Guftaar Ahmad Sardar Sidhu Advisor: Prof. Dr.-Ing. Werner Henkel, Neele von Deetzen Time frame: Spring 2006 Description: The distance spectrum of an (n,k)-convolutional code is given by a transfer function T(W,D,L). where W,D,L represent the input weight, the output weight, and the length of the sequence, respectively. The task was
Student: Jalal Etesami Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2012 Description: We introduce a reconciliation procedure for physical key generation based on specially designed LDPC codes using Slepian-Wolf-type coding. The LDPC codes are optimized for intrinsic information with two different noise variances within the same codeword.
Student: Behrouz Touri Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2007 Description: In this project, our objective was to study the channel response of water filled ducts. Our motivation to do such a project was to see the possibilities of information transmission using water-filled pipes. Since water pipes are frequently
Student: Lucile Sassatelli (diploma student of ENSEA, Sergy-Pontiose, France) Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: April 4 – Sept 3, 2005 Description: In this work, we have proposed a method to optimize the unequal error protection properties of LDPC Codes. We have shown that it is possible to adapt the
Student: Vlad-Andrei Lazar (undergraduate student at IUB) Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Spring 2005 Description: We calculate the error probabilities in Reed-Solomon coded words taking into account both errors and erasures. This is calculated for Gray coded QAM constellations assuming only one bit to be erroneous. The occurring errors and erasures
Student: Neele von Deetzen (diploma student of the University of Bremen and now PhD student at Jacobs University) Advisor: Prof. Dr.-Ing. Werner Henkel, Prof. Dr.-Ing. Karl Dirk Kammeyer Time frame: August 31, 2004, February 28, 2005 Description: In this work, we discussed possible solutions for achieving unequal error protection based on
Student: Vimtakhul Azis (master program FH Darmstadt) Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: February – July 2003 Grants: We appreciate funding by Infineon Description: The major drawback of multi-carrier transmission is the high peak-to-average power ratio of the time-domain signal resulting from the combination of many carriers (central limit theorem). Without countermeasures,
Student: Carsten Walther Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: 04/07/2003 – 05/07/2003 Presently, all kinds of cable connections into and inside the house are used for data transmission. Telphone wires, e.g., support xDSL data connections of up to 14.5 MBit/s. Power-line communications have been considered to be a possible alternative to
Editors: Michael Steinmann, Holger Mehrholz Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: 02/24/2003 – 04/24/2003 Description:In the Studienarbeit a safe web environment is to be provided, which exhibits the following outlined characteristics. As contents of the associated Web environment, sites are to be written, which describe the area and activities and additionally
We investigate nonstationary disturbances in wireline and wireless systems. In wireline, we make us of the common-mode signal to cancel impulse noise from the differential mode or use the common mode to forecast error positions. In wireless, we model impulse noise on antenna arrays caused by ignition, electrical machines, MRI equipment, and alike. Furthermore, we
Work in xDSL focuses on problems of multicarrier transmission, like PAR reduction, time-domain equalization, bit-allocation. To name just a few outcomes of this research: First real capacity optimizing time-domain equalizer PAR reduction scheme which is widely used (many million installations) A bit-allocation scheme allowing for arbitrary SNR margins between priority
We designed UEP Turbo and LDPC codes based on puncturing and pruning. In Turbo codes, pruning and puncturing with time-varying patterns allow for easy variation of the rate and gain. UEP LDPC codes were designed based on a irregular check profile. The applied pruning procedure allowed rate and gain adaptation according to given requirements. UEP
We found that the iterative decoding of analog concatenated codes may be described as iterative projections realizing a least-mean-square solution. This allows for a very intuitive understanding of the iterative Turbo-like decoding procedures. Furthermore, we investigate the correction of bursty noise in additional background noise.
Network codes as a means of reducing the usage of links in a multicast scenario ask for different protection, since error propagation to the end node depends on error locations. Additionally, user data is of different importance and sensitivity. Both ask for suitable coding schemes combining aspects of rate-less and network codes. Different QoS
Our MIMO research focuses on the treatment of imperfect channel information and a possible realization of UEP properties just as in the case of multicarrier transmission. We consider multi-user bit loading, multi-user hierarchical modulation, LDPC coded hierarchical modulation.
Reserving spatial dimensions proved to be very efficient for PAR reduction. With a high numbers of transmit antennas, the corresponding rate loss can be neglected.
We investigate the properties of acoustical wave guides, especially water pipes. The goal will be low-rate data communications for control purposes.
In a joint project with life sciences, we investigate the communications and code properties of the DNA. Our share deals with reasoning of the codon/aminoacid encoding structure, the error-protection, and source coding properties, whereas Prof. Mushelishvili’s group concentrates more on the influences of the three dimensional orientation leading to analog control mechanisms in gene
Student: Nazia Sarwat Islam Advisor: Prof. Dr.-Ing. Werner Henkel Time frame: Fall 2013 Description: Abstract—For physical-layer security, key reconciliation procedures are needed to correct key differences that can arise as a consequence of independent noise at the two ends of a reciprocal link. We assume either a random link in a mobile environment or use