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In motion: Video transmission by mobile drones

Donnerstag, 22. September 2016 14:50

„The information technology specialist Raheeb Muzaffar has developed an application-layer framework that improves the transmission of videos between moving drones and mobile devices located at ground level. His work within the ICE doctoral programme will be completed soon. He explains what makes this technology innovative and talks about his plans for the future in a conversation with Romy Mueller (AAUNews).“ Read more on Medium …

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Thema: Institut, Lakeside Labs, NES | Kommentare (0) | Autor:

Interference alignment in a nutshell

Freitag, 13. März 2015 15:14

There are different strategies on how to handle and manage interference in wireless networks. The choice of strategy mainly depends on the signal-to-interference ratio (SIR) at the receiver. If interference is very weak, it should be ignored and treated as noise. If interference is stronger—about as strong as the desired signal—we want to avoid it and allow only one node to transmit at a given time or frequency in a certain spatial region (orthogonalization). Both strategies are commonly used in wireless technologies in practice. If interference is even stronger than the signal of interest, it is favorable to allow interference and decode it at the receiver rather than to avoid it. A major limitation of all three strategies is that their per-node throughput decreases with an increasing number of transmitting nodes.

Jorge F. Schmidt explaining interference alignment

This fundamental challenge is tackled by interference alignment, which is a „revolutionary wireless transmission strategy“ (El Ayach) that gives a fresh perspective on capacity limits and has the potential to significantly improve the spectral efficiency of wireless communications. […]

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Thema: Institut, NES | Kommentare (0) | Autor:

Internship or Master Thesis: Real-Time Wireless Communication Industrie 4.0

Freitag, 31. Oktober 2014 12:16

Your responsibilities:
You will be a part of a research team at Robert Bosch GmbH working on a networking platform for connected manufacturing in future factories (Industrie 4.0). Your main tasks will include:

  • Evaluation of real-time operation systems for embedded wireless devices (IEEE 802.15.4, Bluetooth, WLAN)
  • Setting-up a testbed for a wireless network with real-time services
  • Design and implementation of service and packet scheduler

Your competencies and qualifications:

  • Student of Electrical Engineering, Computer Science, or similar
  • Good programming skills in C/C++
  • Solid Linux user with first programming experience of embedded devices (Arduino, OpenWRT, TinyOS, embedded Linux, etc.)
  • Good knowledge of (wireless) networking protocols (MAC and routing)
  • Well-organized, responsible, and independent working style

Date and location:

  • Start: Dezember 2014
  • Length: 6 months
  • Job location: Renningen

Reference no.: DE00327359. Apply here. Please attach your examination regulations and when indicated work permit and legal alien resident. For more information contact Dr. Marchenko. Tel.: +49-711-811- 24518.

 

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Thema: DA_Mobile Systems, DA_NES, Diplomarbeit, Institut, NES, PR_Mobile Systems, PR_NES, Praktikum | Kommentare (0) | Autor:

Interference functionals in wireless networks

Sonntag, 12. Oktober 2014 15:16

Interference functionals in wirless networks

Wireless networks are often modeled using tools from stochastic geometry. A team of researchers from Klagenfurt, Athens, and Notre Dame now contributed to these tools by solving general sum-product functionals for Poisson point processes. Link outage probabilities are derived for networks with interference and Nakagami fading.

Multiple access interference in wireless networks occurs if the communication from a transmitter to a receiver is disturbed by additional nodes transmitting in the vicinity of the receiver on the same frequency band and at the same time. Interference can be mitigated or even exploited in networks with central entities using scheduling and signal processing techniques. In distributed systems, however, when no dedicated control entities can regulate the access to the shared wireless medium, interference remains a performance-limiting factor, partly because it is subject to considerable uncertainty. Interference also occurs in wireless networks using code division multiple access (CDMA), where multiple users are not separated in time or frequency but use different spreading codes. In this case as well, interference signals, albeit with reduced power density due to the spreading, add up at the receiver.

[…]

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Thema: Institut, NES | Kommentare (0) | Autor:

Project kickoff: Decision making in networks with errors

Donnerstag, 20. Dezember 2012 10:29

The Lakeside Labs project SOSIE takes an interdisciplinary perspective on decision making in networks suffering from information errors. Human organizations and technical communication systems are compared to identify similarities and differences during decision making processes. Successful techniques may then be transferred from one discipline to the other.

Friederike Wall, who initiated the project together with Christian Bettstetter, is excited about the topic: „The two disciplines have so much in common, I’m sure our partnership will be mutually beneficial.“

Doris Behrens and Pasquale Grippa joined the team as senior researcher and PhD researcher, respectively. Funding is obtained via Lakeside Labs from ERFE, KWF, and the state of Austria.

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Thema: Forschung, Institut, Lakeside Labs, NES | Kommentare (0) | Autor:

Estimating device cardinality using probabilistic trials

Montag, 9. Januar 2012 15:25

Some protocols and applications in mobile computing require that a device knows as to how many other devices exhibiting a certain attribute are in its radio coverage. Obtaining this cardinality information by message exchange between devices is reliable but inefficient in dense networks in terms of overhead and delay. Performing an estimation of the cardinality using probabilistic trials is an alternative.

Adam, Yanmaz, and Bettstetter pursue such a probabilistic approach by proposing cardinality estimator protocols that require no coordination among polled devices but are based on a simple random access scheme with busy tones exploiting the number of empty slots to infer about cardinality. Their forthcoming article in IEEE Transactions on Mobile Computing compares three estimators with different levels of adaptability and feedback from the query device and discusses suitability for IEEE 802.11 and low power sensors.

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Thema: Forschung, Institut, Lakeside Labs, NES | Kommentare (0) | Autor:

Zufälliges Fluten in Zufallsnetzen

Freitag, 30. Dezember 2011 23:50

Probabilistic Flooding in Stochastic Networks

A node intends to deliver a message to all other network nodes using probabilistic flooding, i.e., each node forwards a received message to all its neighbors with a common network-wide forwarding probability ω. Question is: what is the minimum ω-value each node should use, such that the flooded message is obtained by all nodes with high probability?

We first present a generic approach to derive the global outreach probability in arbitrary networks and then focus on Erdős Rényi graphs and random geometric graphs.

Crisóstomo, Schilcher, Bettstetter, Barros. Probabilistic Flooding in Stochastic Networks: Analysis of Global Information Outreach. Computer Networks, vol. 56, no. 1, pp. 142-156, Jan 2012.

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Thema: Forschung, Institut, Lakeside Labs, NES | Kommentare (0) | Autor:

Interference dynamics in wireless networks

Freitag, 14. Oktober 2011 8:45

Interference has significant impact on the performance of wireless communication systems. A comprehensive understanding of its dynamic behavior over time is important for the design of diversity schemes and protocols, whose performance can severely degrade in case of highly-correlated interference.

Schilcher, Bettstetter, and Brandner aim at advancing this emerging field from a theoretical perspective. Their forthcoming article to be published in the IEEE Transactions on Mobile Computing derives closed-form expressions and calculation rules for the correlation coefficient of the overall interference power received at a certain point in space. „We take into account three sources of correlation: node locations, channel, and traffic,“ Schilcher says. It took the team more than one year to find solutions for 27 scenarios presented in the article. The hard work payed off.

Schilcher recently also defended his doctoral thesis with distinction. „This is an important research direction,“ the external PhD examiner, Martin Haenggi from the University of Notre Dame (USA), says. „The spatial and temporal structure of interference has been largely ignored, although it is critical to the performance of wireless networks. The Klagenfurt group made an original contribution that greatly enhances our understanding of interference.“

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Thema: Forschung, Institut, Lakeside Labs, NES | Kommentare (0) | Autor:

Selbstorganisierende Synchronisation: Konvergenzbeweis und Exzellenzstipendium

Dienstag, 12. Juli 2011 12:18

Das synchrone Blinken von Glühwürmchen ist ein beeindruckendes Beispiel für Selbstorganisation. Tausende dieser Tierchen sammeln sich in Bäumen und blinken im Takt, ohne dass ein „Dirigent“ diesen vorgibt. Dieses in Asien auftretende Phänomen lässt sich mit der Theorie gekoppelter Oszillatoren erklären, die auch vielen anderen Synchronisations- und Koordinationsphänomenen zugrunde liegt z. B. Schlafzyklen, Feuern von Neuronen und Schwingungsverhalten von Brücken.

Wissenschaftler des Forschungsclusters Lakeside Labs der Universität Klagenfurt forschen auf diesem Gebiet und möchten es auf technische Anwendungen – im speziellen auf drahtlose Kommunikationsnetze – übertragen. „Synchronisation ist ein wichtiger Funktionsbaustein in großen vernetzten eingebetteten Systemen“, erklärt der Projektleiter Christian Bettstetter. Dabei soll Synchronität auf verteilte Art und Weise ohne zentrale Steuerung erreicht werden.

Dem Team ist es gelungen, einen Algorithmus zu entwickeln, der sich in drahtlosen Systemen zu bewähren scheint. Er wird derzeit auf einer Hardwareplattform implementiert und im Feld getestet. Johannes Klinglmayr zeigt sich mit ersten Ergebnissen zufrieden. „Wir hoffen, dass sich unsere vielversprechenden Simulationsergebnisse mit den Messungen unter realistischen Bedingungen decken“, meint der Forscher und Doktorand am Institut für Vernetzte und Eingebettete Systeme.

In einem von der FFG geförderten Projekt werden auch Fragen der Robustheit untersucht, das heißt inwieweit fehlerhafte Geräte bei selbstorganisierender Synchronisation stören. Was passiert, wenn sich ein oder mehrere Geräte nicht dem Algorithmus entsprechend verhalten? Die Antwort hofft man in einer Kombination aus neurowissenschaftlichen und eigenen Erkenntnissen zu finden. „Es ist uns gelungen, die Konvergenz des Verfahrens mathematisch zu beweisen. Unsere jüngsten Ergebnisse werden demnächst in den ACM Transactions on Autonomous and Adaptive Systems veröffentlicht“, freut sich Klinglmayr.

Kürzlich hat der Nachwuchswissenschaftler ein „Exzellenzstipendium“ der Kärntner Industriellenvereinigung im Wert von € 10.000 erhalten, um einige Monate als Gast am Max-Planck-Institut für Dynamik und Selbstorganisation zu forschen.

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Thema: Forschung, Hall of Fame, Institut, Lakeside Labs, NES, Preis/Auszeichnung | Kommentare (0) | Autor:

Patentanmeldungen zu neuen WLAN-Protokollen

Montag, 30. Mai 2011 15:57

Wie verbessert man die Robustheit von WLAN-Kommunikation? Diese Frage stellen sich Wissenschaftler der Forschungsgruppe Mobile Systeme unter der Leitung von Christian Bettstetter. „Ich erhoffe mir Performanzsteigerungen durch die Kooperation von Geräten,“ so der 38-jährige Professor. Falls eine Übertragung z. B. zwischen einem Notebook und einer WLAN-Station nicht erfolgreich ist, so soll ein anderes Notebook Hilfe leisten.

„Was einfach klingt, ist in Wahrheit eine komplexe Ingenieursaufgabe“, stellt Privatdozent Wilfried Elmenreich klar. Das Projektteam entwickelte in monatelanger Arbeit ein Kommunikationsprotokoll, mit dem sich das Prinzip der Kooperation verwirklichen lässt. „Wichtig ist die Rückwärtskompatibilität zu WLAN-Systemen nach dem IEEE 802.11-Standard“, so Doktorand Helmut Adam.

Die Ideen der drei Forscher wurden in zwei Patentanmeldungen beim Europäischen Patentamt geschützt und nun veröffentlicht. Sie sind unter den Kürzeln EP 2326029 und EP 232630 als Volltext im Web erhältlich.

Derzeit ist das Forscherteam dabei, die Erfindungen in die Praxis umzusetzen. Auf einer programmierbaren Hardwareplattform werden die Kommunikationsprotokolle implementiert und mittels Messungen in großen Fabrikhallen getestet und evaluiert. Für diese Test werden noch studentische Mitarbeiter gesucht.

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Thema: Forschung, Institut, Lakeside Labs, NES, PR_Mobile Systems, PR_NES, Praktikum | Kommentare (0) | Autor: