http://www.bettstetter.com en-us ]]> Cooperative relaying has been developed for wireless communications to mitigate the negative effects of small-scale fading caused by multipath propagation. A huge amount of research has been done in the past ten years to assess benefits and drawbacks of such techniques by simulations and analytical means. It is surprising, however, that only few studies with real-world measurements in realistic environments were published so far. The goal of a research team lead by Christian Bettstetter at Klagenfurt's NES institute is to contribute toward closing this research gap. Based on an implementation of a simple cooperative relaying protocol on the programmable radio platform WARP, measurements were conducted to evaluate the packet delivery performance in a car-to-car communications scenario. The results will be published in IEEE Wireless Communications Letters. "We studied the ratio and temporal correlation of packet delivery for suburban and highway environments using three cars serving as sender, relay, and destination," Günther Brandner, a researcher in the project team, explains. http://bettstetter.com/#120321 21 Mar 2012 21:00:00 ]]> The Austrian federal minister for science and research, Karlheinz Töchterle, visited Lakeside Labs in Klagenfurt. He and his delegation received an overview of research activities and a short demonstration of aerial robots. A press conference concluded the meeting. Professor Töchterle also participated in a plenary discussion in the afternoon and gave a talk titled "Mass university versus excellence in science: a dilemma in Austria's university politics" at the Federation of Austrian Industries in the evening. http://bettstetter.com/#120307 07 Mar 2012 18:00:00 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. http://bettstetter.com/#120109 09 Jan 2012 18:00:00 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." http://bettstetter.com/#111014 14 Oct 2011 09:30:00 Crisostomo, Schilcher, Bettstetter and Barros investigate probabilistic information dissemination in stochastic networks. The following problem is studied: A source 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 forwarding probability w. Question is: which minimum w-value needs to be met by each node to ensure receipt of the flooded message by all nodes with high probability? A forthcoming article in the journal Computer Networks presents a generic approach to this problem in arbitrary networks and then focuses on Erdös Rényi graphs (ERGs) and random geometric graphs (RGGs). An exact solution is given for ERGs. An asymptotic expression is given for RGGs, which is shown to be an approximation for networks with high node density. In both cases, unreliable links are taken into account. http://bettstetter.com/#110829 11 Aug 2011 18:00:00 Peter Illetschko live from Klagenfurt. http://derstandard.at/1308681071864/Insekten-Kolonien-als-Vorbild-Machen-wir-es-doch-wie-die-Ameisen 13 Jul 2011 08:00:00 The synchronous flashing of fireflies is a spectacular example for self-organization in nature. Thousands of fireflies gather in trees and flash in unison using a distributed mechanism that can be understood using the theory of coupled oscillators. This theory has successfully been used for modeling many other synchronization and coordination phenomena, such as sleep cycles, firing of neurons, and vibration of bridges. Researchers at Lakeside Labs aim at advancing this field of science and transferring it to technological applications, in particular to wireless communication networks. "Synchronization is an important building block in large networks of embedded systems," project leader Christian Bettstetter argues. Synchrony should emerge in a distributed manner without having to rely on central entities. Indeed the team has developed a solution that seems to work well in wireless systems. It is now being implemented in a programmable hardware platform for field tests. Johannes Klinglmayr is already very excited about the results. "Let's see whether measurements in a real-world environment will confirm our promising simulation results" the researcher and PhD candidate at the University of Klagenfurt says. Lakeside Labs also investigates robustness aspects of self-organizing synchronization against faulty devices. What happens if one or more devices misbehave in some manner? The idea is to use an approach from neuroscience and combine it with own results. "We have mathematically proven that the resulting algorithm converges," Klinglmayr proudly concludes. "Our latest results will appear in the ACM Transactions on Autonomous and Adaptive Systems." The Federation of Austrian Industry recently awarded the young scientist with a Euro 10.000 scholarship to promote his work and spend a sabbatical at the Max Planck Institute for Dynamics and Self-Organization in Germany. http://www.bettstetter.com/#110712 12 Jul 2011 12:00:00 How to improve the robustness of WLAN communications? Researchers at Klagenfurt's mobile systems group lead by Christian Bettstetter aim at answering this question. "I expect performance gains using the concept of cooperation between devices," the 38-year old professor says. If data transmission between a notebook and a WLAN station fails, another notebook or any mobile device will be of assistance. "Sounds simple but in fact is quite an engineering challenge," senior researcher Wilfried Elmenreich points out. It took the project team several months to develop a communication protocol that realizes the concept of cooperation. "The backwards compatibility to existing IEEE 802.11 WLAN systems is an important feature," PhD candidate Helmut Adam adds. The ideas of the three scientists were filed as patent applications at the European and US patent offices. The manuscripts have recently been published and are available for download using the identifiers EP 2326029 and EP 232630. The research team is now busy implementing the communication protocol on a programmable hardware platform to field-test and evaluate the inventions. Students who would like to join the research project are very welcome. http://www.bettstetter.com/#110601 01 Jun 2011 18:00:00 Computers processors have been leaving offices and become more and more embedded into everyday objects. Enhanced with sensors and networked via wireless connections, these computerized objects allow new fields of application, such as smart homes and remote health monitoring. The IEEE/ICE Summer School on Networked Embedded Systems will feature research-oriented lectures on selected topics in this emerging area. Being part of the Erasmus Mundus PhD program Interactive and Cognitive Environments (ICE), it will take place in Klagenfurt from September 3-7 and is open to the public upon registration. Speakers include, among others, Ian F. Akyildiz (Georgia Tech) on nano networks, Andrea Cavallaro (QMUL) on camera networks, Carlo Regazzoni (Genova) on data fusion, and Kai Römer (Lübeck) on sensor networks. A dinner talk will be given by Infineon Austria CTO Reinhard Petschacher. The social event will include an excursion to Infineon in Villach. The event is technically co-sponsored by the IEEE. http://www.bettstetter.com/#110408 08 Apr 2011 18:00:00 Lakeside Labs is now offering content on Apple iTunes U, the leading platform for educational videos. Categories include lectures from scientists, courses on academic careers, interviews with researchers, and research highlights. http://www.bettstetter.com/#110406 06 Apr 2011 18:00:00 About 50 participants from 16 countries attended the Fifth International Workshop on Self-Organizing Systems hosted by Martina Zitterbart and her team in Karlsruhe (Germany). The two-day event started with an exciting keynote address of Hermann Haken, a pioneer in the field of self-organizing systems. He outlined his work ranging from laser theory to information theory and pattern recognition to nano robots. The workshop featured ten paper presentations in four sessions on the design and analysis of self-organizing systems, wireless networks, and peer-to-peer networks. Topics included evolutionary design, distributed clustering, self-localization, self-repair, and routing. All papers have been published in the book Self-Organizing Systems edited by the program chairs Christian Bettstetter and Carlos Gershenson. The best paper award was conferred on François Cantin and Guy Leduc from the University of Liège (Belgium). In two poster sessions, 17 PhD students and PostDocs presented their work and discussed their ideas with fellow researchers. The award for the best poster was given to Helmut Lindner, who is a PhD student at Klagenfurt's NES institute. Cornell professor Hod Lipson concluded the workshop with an inspiring keynote talk on self-reflective machines. He demonstrated several experiments with self-aware mobile robots that evolve ways to walk. According to Lipson, such reflective processes are essential for achieving meta-cognitive capacities. The ZKM, a center for art and media technology, provided a fancy setting for the social event. http://www.bettstetter.com/#110224 24 Feb 2011 18:00:00 Information and communication systems become increasingly complex. Sascha Aumüller from the daily newspaper Der Standard talked with Christian Bettstetter about this problem. The interview "Nobody wants to call the sysadmin" is about self-organization that can help to overcome the limitations of today's technological possibilities. Lakeside Labs founder Bettstetter also talks about his current projects and Klagenfurt as a science location. http://www.bettstetter.com/#110216 16 Feb 2011 18:00:00 As part of her student project in the mobile systems group, Cam Lai Ngo developed and programmed the iPhone application BUZZflies. With this fun application, you can easily synchronize a set of iPhone devices in time and then let them play a song together, either a song from your library or a built-in song. BUZZflies is thus simulating a distributed loudspeaker. The synchronization is achieved by exchanging sound signals between the devices and employing and demonstrating a synchronization algorithm inspired from nature. The application is available free of charge at Apple's App Store. http://www.bettstetter.com/#100107 07 Jan 2010 18:00:00 The two Lakeside Labs professors Mario Huemer and Christian Bettstetter discussed with Reinhard Petschacher, CTO at Infineon Austria, about the topic of cooperation between industry and universities. The dialog is part of the book "Wissen schaffen," which illustrates the variety of research activities at the University of Klagenfurt. http://www.bettstetter.com/#091202 02 Dec 2009 18:00:00 Alexander Tyrrell passed the defense of his doctorate thesis on synchronization in wireless networks. The examinors were Christian Bettstetter (Klagenfurt) and Rudolf Mathar (RWTH Aachen). 16 Sep 2009 18:00:00 A method for self-organizing slot synchronization suited for wireless systems has been developed. The concepts, architecture, and performance results will be published in a forthcoming article in IEEE Transactions on Mobile Computing. http://www.bettstetter.com/#090910 10 Sep 2009 09:00:00 The Erasmus-Mundus doctorate school Interactive and Cognitive Environments has been accepted for funding. This new training and research program will be offered by the University of Klagenfurt in cooperation with four other European universitites. http://www.bettstetter.com/#090721 21 Jul 2009 09:00:00