Ulrich Sorger

University of Luxembourg

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Foued Melakessou

Luxembourg Institute of Science and Technology

Zdzisław Suchanecki

University of Luxembourg

Axel Heim

Microchip Technology (Germany)

Pascal Bouvry

University of Luxembourg

Andrea Capponi

Azienda Ospedaliera Ospedale Maggiore

Snjezana Gligorevic

Technical University of Darmstadt

Uwe Dettmar

TH Köln - University of Applied Sciences

Dzmitry Kliazovich

University of Luxembourg

Claudio Fiandrino

IMDEA Networks

Peter Adam Hoeher

Kiel University

Cooperative Institutions

University of Luxembourg

Technical University of Darmstadt

Recherches Scientifiques Luxembourg

University of Pisa

Universität Ulm

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

Consorzio Nazionale Interuniversitario per le Telecomunicazioni

Aalborg University

Ericsson (Germany)

University of Trento

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Coherent receiver for AIS satellite detection

Marian Jurado Gallardo Ulrich Sorger

AIS is a universal shipborne Automatic Identification System recently introduced for traffic monitoring and safety at sea. Ships exchange navigational information to identify and localize vessels in a short range to avoid collisions. AIS signals use Gaussian Minimum Shift Keying (GMSK) for transmission. There is a growing need to develop a system which provides global maritime surveillance in order to better handle hazardous cargo transports, to improve safety, and to counteract illegal operations and terrorism. The possibility of extending the system in space to detect ships at long distances from the shore is considered in this paper. Since AIS was not originally designed for space detection, two challenges arise: first, received signals have a large Doppler due to the speed of the satellite, and second, two or more signals from different ships can be received at the same time due to the large coverage of the satellite. In this paper, we proposed an innovative coherent demodulator based on the Maximum Likelihood Estimation (MLE) and a Viterbi decoder to receive AIS signals from space and handle the large Doppler frequency shift. The MLE is used efficiently to estimate the frequency and the channel response.

Automatic Identification System

Minimum-shift keying

Viterbi algorithm

10.1109/isccsp.2010.5463417

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Citations (14)

Multiple decision feedback equalizer for satellite AIS coherent detection

Maria Angeles Jurado Gallardo Ulrich Sorger

The Automatic Identification System is a universal shipborne system adopted to improve safety at sea and efficiency of navigation. This system allows to identify and localize vessels in a short range for collision avoidance by exchanging messages with navigational information.

Automatic Identification System

Identification

10.1109/iscc.2010.5546731

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Citations (2)

A new approach to tracking time-variant channels

Snjezana Gligorevic Ulrich Sorger

This paper presents a method for joint channel and data estimation for transmission over frequency-selective and time-variant channels. Hereby, fast time-variant channels can be tracked, which is important for mobile communications at high velocities. We approach the problem by estimating the scattering function, which depends on delay and Doppler frequency. At the transmitter, a short training sequence is inserted at the beginning of the data block. This sequence is used for initializing a recursive estimation filter, which carries out the joint channel and data estimation adaptively. After the training sequence hypothetical data symbols are considered to extend the persecuted paths in the data tree.

Initialization

Sequence (biology)

Tree (set theory)

Sequential estimation

Tracking (education)

10.1109/wpmc.2002.1088398

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Computation of Moments in the Trellis

Axel Heim Vladimir Sidorenko Ulrich Sorger

Decisions on sources with memory transmitted over independent channels can be taken by employing trellis calculations. In this paper, it is shown that for a certain class of functions their moments can be computed in the trellis, too. This is done by generalizing the forward/backward recursion known from the BCJR algorithm [1]. In analogy to the symbol probabilities, by introducing a constraint at a certain depth in the trellis we obtain symbol moments. These moments are required for an efficient implementation of the discriminated belief propagation algorithm in [2], and can furthermore be utilized to compute conditional entropies in the trellis. The moment computation algorithm has the same asymptotic complexity as the BCJR algorithm. It is applicable to any commutative semi-ring, thus also providing a generalization of the Viterbi algorithm [3].

Trellis (graph)

BCJR algorithm

Viterbi algorithm

Iterative Viterbi decoding

Belief Propagation

10.1109/isit.2008.4595441

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Quality-of-Service-Aspekte in mobilem Kontext

Matthias Finke Ulrich Sorger

Computing kommt im Alltag immer mehr zum Einsatz. Benutzer mochten mittels Ihrer mobilen Gerate in der Lage sein Zugriffe auf Ressourcen im Netz und auf Multimedia-Applikationen (z. Bsp. Videokonferenzen) zu haben. Durch die physikalischen Eigenschaften des Mobilnetzes kann es aber zu einer Minderung der Qualitat kommen. Da Multimedia-Daten, wie Video oder Audio, sehr zeitkritisch sind, Bedarf es hierfur spezieller Losungen. Diese Problematik kann durch Quality-of-Service (QoS) beschrieben und behandelt werden. Diese Studienarbeit befast sich mit QoS hinsichtlich Multimedia und Computing. Es werden hierfur geeignete QoS-Parameter vorgestellt, mittels derer eine Verbesserung der Qualitat moglich ist. Weiterhin gibt diese Studienarbeit eine kurze Einfuhrung in den neuen Technologien der Mobilkommunikation, wie BLUETOOTH oder UMTS (Universal Mobile Telecommunications System).

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On the road towards the comprehension of the internet traffic behavior: simulation and analysis of an end-to-end connection with ns-2

Annual Simulation Symposium (2007)

Foued Melakessou Ulrich Sorger Zdzisław Suchanecki

This contribution is attempting to address the problem of understanding how different aspects of networks - physical topology and routes on that topology - along with packet arrival models lead to congestion and other observed network characteristics as its fractal and periodic behavior. We reveal topology and routing effects on data transmissions between two routers linked by a connection path in a well-defined network environment. Our statistical approach is based on log-normal distributions. We show that the fractal behavior of a network node traffic can be viewed as a consequence of the topology and routing effects. This work is based on random simulations performed by the network simulator ns-2. We have shown that the longer the connection path, the more log-normal is the inter-arrival time distribution at the destination node. Moreover a spectrum analysis has been performed in order to emphasize the traffic periodic behavior rising from the most used transfer protocol TCP/Reno.

10.5555/1404595.1404625

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Citations (8)

Time Operators and Approximation of Continuous Functions

International Journal of Theoretical Physics (2007)

Ulrich Sorger Z. Suchanecki

Haar

Spectral theorem

Characterization

10.1007/s10773-007-9622-9

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Citations (5)

Concatenated codes with convolutional inner and outer codes

Lecture notes in computer science (1994)

Uwe Dettmar Ulrich Sorger Victor Zyablov

Convolutional code

Turbo code

10.1007/3-540-58265-7_11

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Citations (1)

New optimal partial unit memory codes based on extended BCH codes

Electronics Letters (1993)

Uwe Dettmar Ulrich Sorger

Some new optimal binary partial unit memory codes are presented. The codes are constructed from extended BCH codes. A general method for constructing PUM codes based on extended RS and BCH codes is described.

BCH code

10.1049/el:19931351

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Citations (19)

Delays of Interconnected Flows

International Journal of Theoretical Physics (2011)

Ulrich Sorger Z. Suchanecki

Transversal (combinatorics)

Independence

10.1007/s10773-011-0724-z

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Citations (1)