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Foto: Judith Kraft

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Towards Predicting Resource Demands and Performance of Distributed Cloud Services

S. Dräxler, M. Peuster, M. Illian, H. Karl, 2018


Understanding the behavior of distributed cloud service components in different load situations is important for efficient and automatic management and orchestration of these services. For this purpose and for practical research in distributed cloud computing in general, there is need for benchmarks and experimental data. In this paper, we describe our experiments for characterizing the relationship between resource demands of application components and the expected performance of applica- tions. We present initial results for predicting the interdependence between resource demands and performance characteristics using support vector regression and polynomial regression models. The data gathered from our experiments is publicly available.

Adding Geographical Embedding to AS Topology Generation

A. Schwabe, H. Karl, in: CoRR, 2014

Specifying and Placing Chains of Virtual Network Functions

S. Mehraghdam, M. Keller, H. Karl, in: CoRR, 2014

Denser Networks for the Future Internet, the CROWD Approach

A. de la Oliva, A. Morelli, V. Mancuso, M. Draexler, T. Hentschel, T. Melia, P. Seite, C. Cicconetti, in: Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, Springer Berlin Heidelberg, 2013, pp. 28-41


A Scalable Redundant TDMA Protocol for High-Density WSNs Inside an Aircraft

J. Blanckenstein, J. Garcia-Jimenez, J. Klaue, H. Karl, in: Lecture Notes in Electrical Engineering, Springer International Publishing, 2013, pp. 165-177


Anticipatory Buffer Control and Quality Selection for Wireless Video Streaming

M. Dräxler, J. Blobel, P. Dreimann, S. Valentin, H. Karl, in: CoRR, 2013

Introducing feedback to preemptive routing and wavelength assignment algorithms for dynamic traffic scenarios

P. Wette, H. Karl, Universität Paderborn, 2012


Preemptive Routing and Wavelength Assignment (RWA) algorithms preempt established lightpaths in case not enough resources are available to setup a new lightpath in a Wavelength Division Multiplexing (WDM) network. The selection of lightpaths to be preempted relies on internal decisions of the RWA algorithm. Thus, if dedicated properties of the network topology are required by the applications running on the network, these requirements have to be known by the RWA algorithm. Otherwise it might happen that by preempting a particular lightpath these requirements are violated. If, however, these requirements include parameters only known at the nodes running the application, the RWA algorithm cannot evaluate the requirements. For this reason a RWA algorithm is needed which involves its users in the preemption decisions. We present a family of preemptive RWA algorithms for WDM networks. These algorithms have two distinguishing features: a) they can handle dynamic traffic by on-the-fly reconfiguration, and b) users can give feedback for reconfiguration decisions and thus influence the preemption decision of the RWA algorithm, leading to networks which adapt directly to application needs. This is different from traffic engineering where the network is (slowly) adapted to observed traffic patterns. Our algorithms handle various WDM network configurations including networks consisting of heterogeneous WDM hardware. To this end, we are using the layered graph approach together with a newly developed graph model that is used to determine conflicting lightpaths.

Scenarios, Research Issues, and Architecture for Ubiquitous Sensing

T. Kanter, V. Kardeby, S. Forsström, J. Walters, in: Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, Springer Berlin Heidelberg, 2011, pp. 285-297


How to manage and Search/Retrieve Information Objects

C. Dannewitz, e. al, in: Architecture and Design for the Future Internet, 2011

Integrating Generic Paths and NetInf

C. Dannewitz, e. al, in: Architecture and Design for the Future Internet, 2011

Selected properties of a joint congestion controller for TCP connections

M. Savorić, H. Karl, A. Wolisz, in: Providing Quality of Service in Heterogeneous Environments, Proceedings of the 18th International Teletraffic Congress - ITC-18, Elsevier, 2010, pp. 861-870


Creating Butterflies in the Core – A Network Coding Extension for MPLS/RSVP-TE

T. Biermann, A. Schwabe, H. Karl, in: NETWORKING 2009, Springer Berlin Heidelberg, 2009, pp. 883-894


Network-Coding-Based Cooperative Transmission in Wireless Sensor Networks: Diversity-Multiplexing Tradeoff and Coverage Area Extension

D.H. Woldegebreal, H. Karl, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, 2008, pp. 141-155


Experimental evaluation of IEEE 802.11a-based WLANs for medium range communication

F. Eitzen, S. Valentin, K. Gossens, H. Karl, O. Rolfes, 2007

Ad Hoc Networks

H. Karl, in: The Industrial Information Technology Handbook, 2005, pp. 1--16

Data Transmission in Mobile Communication Systems

H. Karl, in: Location-Based Services, 2004, pp. 207--244

A common wireless sensor network architecture?

V. Handziski, A. Köpke, H. Karl, A. Wolisz, 2003

Relaying in Wireless Access Networks

H. Karl, S. Mengesha, D. Hollos, Business Briefing: Wireless Technology 2002, 2002

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