Martin Lipphardt

MarathonNet: adding value to large scale sport events - a connectivity analysis

The project MarathonNet develops wireless sensor networks for monitoring runners during marathon events. The application requires a high degree of connectivity in order to provide actual data for runners and spectators. Depending on the distribution of the runners on the track, the communication range and the number of base stations network partitions might occur that reduce connectivity. To investigate these dependencies in detail we conducted various simulations on connectivity. In this paper we first introduce the application scenario and discuss the impact of the different parameters and their interrelations. We then present the simulation results and discuss their consequences for the application design.

Using graphical process modeling for realizing SOA programming paradigms in sensor networks

Designing and modifying sensor network applications demand for IT expertise in the field of distributed systems. Programming paradigms used in application development for sensor networks like object orientation do not refer to the distributed nature of a sensor network application. This represses the usage of sensor network technology as part of industrial applications. In enterprises graphical tools like BPEL and BPMN are used to coordinate distributed processes and overcome the complexity of the interaction among different components. In this work we introduce the GWELS toolbox as graphical process modeling tool to realize the service oriented programming paradigm for sensor networks and ease the development and integration of sensor network applications. We exemplarily design and deploy a sensor network application with GWELS to demonstrate the applicability of our approach.

Integrating standardized transaction protocols in service-oriented wireless sensor networks

Despite much research in the area of wireless sensor networks in recent years, the programming of sensor nodes is still time-consuming and tedious. A new paradigm which seems to be qualified to simplify the programming of sensor networks is the Service Oriented Architecture. The composition of simple services to more complex ones can be a convenient way to design applications. To enable the sophisticated techniques known from service oriented architectures like replication and migration of services, a transaction model for sensor networks is required. In this paper, we study the applicability of the standard commit protocols Two Phase Commit (2PC) and Transaction Commit On Timeout and show in experiments with real sensor nodes that 2PC can enable consistent service migration in wireless sensor networks.

DySSCo - A Protocol for Dynamic Self-Organizing Service Coverage

Service oriented middleware draws a lot of attention in current research on sensor networks. The automatic distribution of services within a network and the preservation of this distribution is a fundamental aspect of network applications with self-x properties. The network gains the ability to react on mobility, network fragmentation, node failures and new user demands. This paper proposes a distributed self-organizing algorithm for service distribution and preservation of this distribution using demanded coverages for the services. After discussing the theory of the convergence of the algorithm, this paper presents a real-world deployment of a sensor network scenario and evaluates the performance of the algorithm.

Stream-Based XML Template Compression for Wireless Sensor Network Data Management

Using structured data formats like XML in wireless sensor networks to support exchangeability and heterogeneity on application level has become an important research topic in the area of large scale networked sensing systems. Besides, the usage of XML encourages the adaptation of service oriented programming techniques to simplify sensor network application engineering. While the sensor nodes still have significant resource limitations in terms of energy and memory capacity and computational power, recent data management approaches show positive results to bridge this resource gap. Nevertheless, further optimizations are needed to enhance the application range to support larger sets of data within the networks. In this work we present an optimization for a template object compression scheme that is based on a stream-oriented XML compression and supports dynamic data management and query evaluation on the compressed data. We hereby present a complete solution for XML compression, data processing and query evaluation that can be further embedded in the engineering process to support developers. The presented solutions are evaluated and result into significant improvements in comparison to previous approaches, when processing complex large scale XML documents.

FRED - An Application for a Real-Life Large Scale Multihop Ad Hoc Network

Simulations were standard in the mobile ad hoc network (MANET) research community in the past New protocols and algorithms were validated via simulations by network simulators such as ns2 or GloMoSim. However, even with the increasing number of published simulation papers, contradictory results are decreasing the confidence in simulations today. First experimental results show that simulation models for ad hoc networks are far from being realistic and protocols developed in simulations failed in real word environments. As a result, the demand for experimental results and application deployments within the research community increases. In this paper, we introduce FRED as a suitable application to conduct protocol evaluations as well as user acceptance surveys. FRED (flexible radio enabled dialog) is an enhanced TED-System that allows asynchronous surveys or quizzes with a multi hop radio network, where individual participants conduct the survey independent of others. FRED is based on the pacemate sensor network platform that provides a comfortable lightweight housing, a simple radio interface and an intuitive GUI that allows long term evaluations of user acceptance and network protocols.

A service-oriented operating system and an application development infrastructure for wireless sensor networks

Due to the highly distributed nature and special basic conditions such as limited resources, implementing and maintaining a sensor network application is a tedious task. In this demonstration we present a service-oriented operating system for sensor nodes and a framework that allows a composition of services on the nodes. We show how sensor network applications can be composed and modified by using different services.

GRAPE - Gradient based Routing for All PurposE

Routing within wireless mobile multi-hop networks is a challenging task. Therefore, in the past several routing protocols have been developed with various extensions and adoptions to certain specific scenarios. The consensus of the discussion about routing is that depending on all aspects of their application reaching from number of nodes, mobility, to the data traffic profile of the application developers can choose an optimal routing protocol. In the meantime some routing protocols have evolved as standard choice like AODV, DSR, OLSR, TBRPF. With the advent of sensor networks, requirements like scalability and resource consumption are added to the research domain. This resulted in additional extremely specialized routing algorithms or special extensions to existing protocols. So is there really a need and room for another routing protocol? We are convinced that a really simple, efficient, scalable protocol that allows for mobility and is suited for various performance classes of devices does not exist. We propose GRAPE as a completely new approach for routing in wireless multi-hop networks and present performance results based on simulations and measurements that demonstrate the potential of the routing approach.

Praxiserfahrungen mit MarathonNet – Ein mobiles Sensornetz im Sport

ZUSAMMENFASSUNG Das Forschungsgebiet der Sensornetze sieht massiv verteilte Anwendungen mit einer Vernetzung von hunderten oder tausenden von kleinen meist batteriebetriebenen autarken Endgeräten vor. Aufgrund der zurzeit noch teuren Hardware und des hohen Aufwands von Feldversuchen basieren die Ergebnisse heutzutage weitestgehend auf Simulationen. Der Übergang von der Simulation zum praktischen Einsatz wird von Forschern zunehmend als eine neue Herausforderung gesehen. Unser Projekt MarathonNet hat das Ziel, in einem attraktiven Anwendungsfeld neu entwickelte Verfahren unter praxisrelevanten Umständen zu testen. Wir präsentieren in diesem Artikel unsere ersten Erfahrungen beim Übergang von der virtuellen Welt der Simulation hin zur Ableitung der Anforderungen an die Hardware und Software und berichten von den Ergebnissen beim ersten Einsatz während eines Marathons.

Self-organizing service distribution

In this demonstration we show how a sensor network application can be composed by different services. We demonstrate how the services dynamically distribute within the network and how this distribution automatically adapts to changes in topology or user demands.