[jan05] January 2005:

Michael Matthes, Holger Biehl, Michael Lauer und Oswald Drobnik: Massive: An Emulation Environment for Mobile Ad-hoc Networks. In Proc. of Wireless On demand Network Systems and Services (WONS2005), IEEE Computer Society, St. Moritz, Switzerland, January 2005.

Abstract

Developing and evaluating protocols and applications for mobile ad-hoc networks requires significant organisational effort when real mobile ad-hoc networks with several mobile terminals are considered. For fine tuning and optimizing ad-hoc protocols, network simulators like the OpNet Modeller, NS2, or GloMoSim are most suitable. However, for the comprehension of the mode of operations of ad-hoc network mechanisms and their effects on the communication flow of applications a real-time experiment environment is more preferable. In this paper, an emulation environment for mobile ad-hoc networks is presented, which operates within existing local area networks utilizing virtual overlay structures reflecting the characteristics of mobile ad-hoc networks. Routing protocols and applications are able to communicate in real-time over emulated mobile infrastuctures using the unmodified IP protocol stack. The emulator provides an extensible interface for specifying mobility patterns in order to define and to evaluate diverse mobile scenarios. Several ad-hoc specific mobility patterns have been integrated and evaluated.

[feb04] February 2004:

Michael Matthes, Felix Apitzsch, Michael Lauer und Oswald Drobnik: Application-oriented Routing for Mobile Ad-hoc Networks. In Proc. of the European Wireless Conference 2004, Mobile and Wireless Systems beyond 3G, Barcelona, Spain, February 2004.

Abstract

In this paper several routing protocol extensions for mobile ad-hoc networks (MANETs) are proposed, which are designed to support a typical class of ad-hoc application scenarios. In the considered scenarios the reachability of essential services, resources, and users is of special interest from an users resp. applications point of view. Mobile terminals gather information about currently offered services and resources. This information is filtered according to individual interests of users. Only communication paths to "interesting" services and resources need to be managed. This paper presents corresponding extensions to the Temporally Ordered Routing Algorithm (TORA), which have been implemented and evaluated in a MANET emulation environment developed by our group. The interaction between the application-oriented routing protocol and an E-learning application for ad-hoc networks is also shown.

[oct03] October 2003:

Michael Lauer, Michael Matthes und Oswald Drobnik: A Framework for Developing Applications for Ad-hoc Environments. Proc. of Software Engineering, Artificial Intelligence, Networking, and Parallel/Distributed Computing (SNPD03), Lübeck, October 2003.

Abstract

Over the recent years there has been an enormous increase of research interest in ad-hoc networking. The development of applications for mobile ad-hoc environments imposes new challenges on the application programmer, because new requirements arise for applications running in such networks. However, applications for ad-hoc networks have a typical style of communication in common. The flow of information is rather determined by specific interests than by explicit well-known sources or destinations. This paper proposes a framework called LEGOLAS to support the development of cooperative ad-hoc aware applications.

[june03] June 2003:

Michael Lauer, Michael Matthes, Markus Ueberall, Oliver Horvath und Oswald Drobnik: CLE: Collaborative Learning Environment. In Poster Proceedings of Computer Support for Collaborative Learning (CSCL03), Bergen, Norway, June 2003.

Abstract

CLE is a computer supported learning environment for analysing scientific artefacts. In a collaborative process a group of students can model the structure of these artefacts. The structure is visualized as a three dimensional concept map. The objective of CLE is to support the analysis and comprehension of scientific artefacts during collaborative group processes.

[mar03] March 2003:

Damian Prokopp, Michael Matthes, Oswald Drobnik und Udo R. Krieger: Integration of Mobility-, QoS- and CAC-Management for Adaptive Mobile Applications. Proc. of Art-QoS 2003: Architecture for Quality of Service in the Internet, LNCS, Springer, Heidelberg, Germany, p.31-49.Warsaw, Poland. März 2003.

Abstract

We sketch a QoS framework for adaptive mobile multi-media environments that integrates mobility- and uality-of-service management with new connection admission control (CAC) schemes. Refering to measurement-based CAC procedures applied in mobile access networks, we discuss their extension to adaptive mobile applications and describe the integration of corresponding resource reservation and CAC policies in our framework. Furthermore, we evaluate the performance of several CAC schemes by a simulation study.

[feb03] February 2003:

Michael Lauer, Michael Matthes und Oswald Drobnik: *ELAN: Konzept einer adaptiven Infrastruktur für Lernumgebungen in Ad-hoc Netzen*. Kommunikation in Verteilten Systemen, (KiVS03), Leipzig, Germany, February 2003.

Abstract

Ad-Hoc Netze stellen aufgrund ihrer inhärenten Dynamik besondere Anforderungen an Mechanismen zur Kommunikationsunterstützung. Der ``einfache'' Zugang zu Ad-Hoc Netzen, der die ``spontane'' Vernetzung von beliebigen mobilen Endgeräten erlaubt, bietet jedoch auch neue Möglichkeiten für Kommunikationsanwendungen. In diesem Beitrag wird das Konzept einer adaptiven Infrastruktur für Ad-Hoc Netze vorgestellt, das durch die Anforderungen von Anwendungen in einer derartigen hochdynamischen mobilen Umgebung definiert ist. Dem Konzept liegt ein spezielles Anwendungsszenario aus dem E-Learning Bereich zugrunde. Anhand dieses Szenarios lassen sich charakteristische Einflüsse von Ad-Hoc Netzen auf Kommunikationsanwendungen identifizieren, so dass das entwickelte Konzept auf beliebige Anwendungsszenarien für Ad-Hoc Netze erweiterbar ist.

[sep02] September 2002:

Michael Lauer und Michael Matthes: ELAN: An E-Learning Infrastructure for Ad-Hoc Networks. Proc. of the 8th ACM International Conference on Mobile Computing and Networking (MobiCom 2002), Poster Presentation. Atlanta, Georgia, USA, September 2002.

Abstract

One of the main objective of an infrastructure for E-Learning in ad-hoc networks is the development of efficient methods to find students with similar interests and to find services providing useful information. Therefore, special mechanisms for distributing awareness information must be provided on several layers ? on the network layer and on the application layer ? which take into account the high dynamics of mobile ad-hoc networks.

[july02] July 2002:

Michael Matthes, Jens Bachmann, Udo Krieger und Oswald Drobnik: A QoS Management System for Adaptive Applications supporting Mobility and End-to-End Guarantees. Proc. of the IASTED International Conference, Wireless and Optical Communications (WOC2002), Banff, Canada, July 2002.

Abstract

Motivated by the current integration of radio access networks and the IP-based high-speed data communication in core networks, we have developed a new quality-of-service management concept for mobile environments. Following the IntServ service model, it provides resource reservation, control and signaling mechanisms and is able to interwork with RSVP in the backbone. The most important new feature is its capability to cooperate with adaptive applications that can adjust their traffic generation processes according to the varying conditions in a mobile environment. We have implemented and validated the concept in a testbed provided by an IEEE802.11b compatible wireless LAN with Mobile IP. The stated experiments with a new adaptive version of the video conference tool Vic reveal the feasibility and performance gains of our approach.

[may02] May 2002:

Jens Bachmann, Michael Matthes, Udo Krieger und Oswald Drobnik: Mobility and QoS-Management for Adaptive Applications. Proc. of 11. International World Wide Web Conference, Hawaii, USA. May 2002.

Abstract

Considering a wireless next generation IP-network and its corresponding QoS-management mechanisms, we sketch the concept of a service architecture where adaptive applications are running on top of the transport and network layers with their resource and mobility-management functionalities. We present an abstract programming model that captures the signaling and control functionality of the flow layer and its communication with the governing resource-management components of the access infrastructure. We illustrate its feasibility by a QoS enhanced LINUX implementation at an advanced testbed of an IEEE802.11 compatible wireless LAN with a Mobile IP network layer. A series of comprehensive experiments and traffic measurements are used to study the interworking of flow control, resource reservation and mobility management and to identify the most effective and most sensitive control information used by the adaptation processes of the application layer.

[jan02] January 2002:

Jens Bachmann, Michael Matthes, Udo Krieger und Oswald Drobnik: Mobility Management and QoS-support for Adaptive Applications in Next Generation Wireless Networks: Concept, realization and traffic measurements. Proc. of Telecommunication Networks and Teletraffic Theory, St. Petersburg, January 2002.

Abstract

Considering a wireless next generation IP network and its corresponding QoS-management mechanisms, we sketch a service architecture where adaptive applications are running on top of the transport and network layers with their resource and mobility management functionalities. We describe a Linux implementation of our concept in an IEEE802.11b compatible wireless LAN with Mobile IP as network layer using a unified programming model. Finally, a series of comprehensive traffic measurements are used to study the interworking of flow control, resource reservation and mobility management.

[mar01] March 2001:

Michael Matthes, Udo Krieger und Oswald Drobnik: On the Efficiency of the Data Transport in an IEEE802.11 wireless LAN with Mobile IP - Myth and Reality. Proc. of Mobile Systems 2001/Mobile Internet, Moskow, March 2001.

Abstract

Currently, the integration of wireless LANs (WLANs) based on IEEE802.11 into IP- or ATM-networks is rapidly evolving. We study the transport efficiency of the TCP and UDP protocols in an advanced testbed. We use Mobile IP as new network layer to support a seamless roaming of mobile terminals. Our measurements reveal the potential and the drawbacks of the approach and provide new insight on the relationship of the signal-to-noise ratio and the dynamics of the TCP flow control. It may be used to develop improved handoff and mobility-management mechanisms for an efficient transport of real-time multi-media and data streams over wireless links in WLANs, GPRS or UMTS networks.

[feb01] February 2001:

Michael Matthes, Udo Krieger und Oswald Drobnik: Auswirkung drahtloser Netzsegmente auf die Transporteffizienz von TCP/IP-Verbindungen. Proc. of Kommunikation in Verteilten Systemen (KiVS 2001), Hamburg, Germany, February 2001.

Abstract

Ein Forschungsschwerpunkt in der Entwicklung von Kommunikationsinfrastrukturen stellt derzeit die Integration von drahtlosen Netzsegmenten in bestehende IP-basierte Festnetze dar. Bestehende Protokolle des Festnetzes berŽücksichtigen jedoch nur unzureichend die EinflŽüsse von funkbasierten ŽÜbertragungswegen (variierende VerbindungsqualitŽäten, MŽöglichkeit des Roamings). Eine effiziente multimediale Datenkommunikation bei Einbeziehung funkbasierter ŽÜbertragungswege erfordert AdaptionsfŽähigkeit auf mehreren Protokollebenen. In diesem Beitrag werden einige der zu berŽücksichtigenden Umgebungsbedingen auf mehreren Protokollebenen anhand von Experimenten in einem drahtlosem LAN mit Mobile-IP auf der Netzwerkebene identifiziert und Hinweise zur Anpassung von KommunikationsstrŽömen formuliert.

[july99] July 1999:

Jürgen Berghoff, Michael Matthes und Oswald Drobnik: Mobile-awareness in Collaborative Learning Environments. Proc. of the 5th International Conference on Information Systems Analysis and Synthesis 1999 (ISAS'99), Orlando, USA, July 1999.

Abstract

Mobility is becoming an increasingly important subject for computer-supported cooperation. Mobile-awareness grows to a major topic for CSCW-systems in mobile environments. In our paper we discuss several awareness concepts for traditional CSCW-systems in the context of mobility. We distinguish three main classes: member-awareness, group-awareness, session-awareness. A general system architecture is proposed based on Mobile-IP. It supports the distribution of awareness information in mobile environments. The integration of mobile awareness concepts into our collaborative learning environment is investigated. Our collaborative learning environment is a kind of knowledge modeling system: the members of the group collaborate to develop a common view of research topics. In a first phase all group members work on their own to build a semiformal representation of the research artifact. In a second phase all group members cooperate to aggregate the individual views to a common representation. An experimental mobile environment is under development to analyze mobile awareness scenarios.

[apr98] April 1998:

Jürgen Berghoff, Josefine Schumann, Michael Matthes und Oswald Drobnik: Communication Support for Knowledge-intensive Services. Proc. of 4th International Conference on Broadband Communications (BC'98), IFIP TC 6/WG6.2, Stuttgart, Germany, April 1998.

Abstract

Knowledge-intensive services gain significant importance for the development of innovative products. Up to now they depend mainly on face-to-face communication. Technological progress in artificial intelligence, groupware, and broadband systems favour computerized support of such services. In this field we focus on the computerized communication support for human interactions. We try to enrich human communication through 3D visualization of problems and research artefacts. A prototype system is under development to assess the required network capacity. It consists of tools for knowledge modeling, group interaction and a multicast protocol.