Carsten Buschmann’s research while affiliated with University of Lübeck and other places

In this work, a secure wireless sensor network (WSN) for the surveillance, monitoring and protection of critical infrastructures was developed. To guarantee the security of the system, the main focus was the implementation of a unique security concept, which includes both security on the communication level, as well as mechanisms that ensure the functional safety during its operation. While there are many theoretical approaches in various subdomains of WSNs—like network structures, communication protocols and security concepts—the construction, implementation and real-life application of these devices is still rare. This work deals with these aforementioned aspects, including all phases from concept-generation to operation of a secure wireless sensor network. While the key focus of this paper lies on the security and safety features of the WSN, the detection, localization and classification capabilities resulting from the interaction of the nodes’ different sensor types are also described.

This poster presents the iBAST project, the goal of which is the continuous monitoring of highway bridges with sensor network technology. Currently working on a first individual solution, the long term goal of the project, though, is to move from individual case studies towards a comprehensive monitoring of bridges, by developing a monitoring system which can be easily and cost-effectively customized for every bridge. This poster abstract presents the system architecture and implementation as well as first results.

In this paper a secure wireless sensor network (WSN) developed within the MOVEDETECT project is presented. The goal of the project was to design, implement and demonstrate a secure WSN for the protection of critical infrastructure. In order to provide a reliable service, the system must detect any kind of tampering with the sensor nodes, prevent eavesdropping and manipulation of the communication as well as detect, track and classify intruders in the protected region. Therefore based on previous experiences, a real-world WSN was developed, which addresses practical issues like water proofing, energy consumption, sensor deployment and visualization of the WSN state, but also provides a unique security concept, a interesting combination of sensors and sophisticated sensor data processing and analysis. The system was evaluated by examining firstly the sensors and the sensor processing algorithms and then conducting realistic field test.

This paper introduces a selective reprogramming scheme for wireless sensor networks, which is reliable, robust and scalable. Selective wireless code replacements are mandatory for real-world deployments where no wired connections exist to a majority of the nodes and where different hardware or different roles lead to a heterogeneous network. The presented scheme is based on the idea that nodes to be updated share missing program parts with each other. We show by real-world experiments and simulations that it reduces the duration of the update process and the number of transmitted messages compared to related work. Even in extremely lossy networks, it reprograms 225 nodes in less than 120 seconds.

Compared to other middleware approaches like CORBA or Java RMI the protocol overhead of SOAP is very high. This fact is not only disadvantageous for several performance-critical applications, but especially in environments with limited network bandwidth or resource-constrained computing devices. Although recent research work concentrated on more compact, binary representations of XML data only very few approaches account for the special characteristics of SOAP communication. This chapter will discuss the most relevant state-of-the-art technologies for compressing XML data. Furthermore, it will present a novel solution for compacting SOAP messages. In order to achieve significantly better compression rates than current approaches, the compressor described in this chapter utilizes structure information from an XML Schema or WSDL document. With this additional knowledge on the “grammar” of the exchanged messages, this compressor generates a single custom pushdown automaton, which can be used as a highly efficient validating parser as well as a highly effective compressor. The main idea is to tag the transitions of the automaton with short binary identifiers that are then used to encode the path through the automaton during parsing. The authors’ approach leads to extremely compact data representations and is also usable in environments with very limited CPU and memory resources.

As battery capacities are a key limiting factor of wireless sensor networks, harvesting energy from the environment is very attractive. For outdoor applications, solar power seems to be the best suited energy source. However, the amount of energy delivered from the sun changes significantly over the year, which makes the dimensioning of the panel difficult. In this paper we discuss the most important impact factors and introduce a model that predicts the harvested solar power and the battery charge over the year. In addition, we present experimental results of the first six month of our long term experiments for validating our model.

For the flexible integration of enterprise applications and business processes, the Service Oriented Architecture (SOA) concept and the web service technology are the state of the art today. Especially for powerful hardware, a lot of web service and related technologies were developed during the last years. But with the development of Future Internet technologies, there is a demand for integrating all kinds of devices into a SOA. This includes especially devices with extremely limited resources, such as wireless sensor nodes, which are not capable of running today's web service technologies. In this paper we disclose the need for research action on different layers of the web service technology stack. We discuss promising solutions for running standard compliant web services in sensor networks and integrating sensor network and enterprise IT web services as well as BPEL business processes seamlessly. We introduce the L2D2 project in which our concept will be realized and proven.

Compared to other middleware approaches like CORBA or Java RMI the protocol overhead of SOAP is very high. This fact is not only disadvantageous for several performance-critical applications, but especially in environments with limited network bandwidth or resource-constrained computing devices. Although recent research work concentrated on more compact, binary representations of XML data only very few approaches account for the special characteristics of SOAP communication. In this article we will discuss the most relevant state-of-the-art technologies for compressing XML data. Furthermore, we will present a novel solution for compacting SOAP messages. In order to achieve significantly better compression rates than current approaches, our compressor utilizes structure information from an XML Schema or WSDL document. With this additional knowledge on the “grammar” of the exchanged messages, our compressor generates a single custom pushdown automaton, which can be used as a highly efficient validating parser as well as a highly efficient compressor. The main idea is to tag the transitions of the automaton with short binary identifiers that are then used to encode the path trough the automaton during parsing. Our approach leads to extremely compact data representations and is also usable in environments with very limited CPU and memory resources.

A weak point of web services is the lack of suitable technologies for implementing service registries. Universal description, discovery and integration (UDDI), as a centralized approach, conflicts with the distributed nature of service-oriented architectures and did not prevail in practice. Hence, in this paper we propose an architecture for discovering and locating web services using the domain name system (DNS). After a detailed survey on current technologies for finding services we present a novel service discovery scheme that is easy to implement and scalable at the same time. Each service provider runs one or more discovery proxies in its Internet domain and sets DNS records pointing to them. Then, local services can register at these proxies. Service users from the local network as well as from the Internet can now locate these proxies using the DNS and query them for available services in this domain. Thus, the local proxies are linked together by the DNS forming one coherent global service directory.