Frank Golatowski

Weighted Centroid Localization in Zigbee-based Sensor Networks

Localization in wireless sensor networks gets more and more important, because many applications need to locate the source of incoming measurements as precise as possible. Weighted centroid localization (WCL) provides a fast and easy algorithm to locate devices in wireless sensor networks. The algorithm is derived from a centroid determination which calculates the position of devices by averaging the coordinates of known reference points. To improve the calculated position in real implementations, WCL uses weights to attract the estimated position to close reference points provided that coarse distances are available. Due to the fact that Zigbee provides the link quality indication (LQI) as a quality indicator of a received packet, it can also be used to estimate a distance from a node to reference points.

SIRENA - Service Infrastructure for Real-time Embedded Networked Devices: A service oriented framework for different domains

The SIRENA project started in 2003 to leverage Service Oriented Architectures (SOA) to seamlessly interconnect (embedded) devices inside and between four distinct domains - the industrial, telecommunication, automotive and home automation domain. A framework was developed to achieve this aim as well as assuring interoperability with existing devices and extensibility of network based on SIRENA technology. The core of the framework is the Devices Profile for Web Services (DPWS) which will play an important role in the upcoming Microsoft Windows. The first DPWS stack worldwide developed by the SIRENA consortium is described and its operation evidenced in several demonstrators. This paper presents the results of the SIRENA project, provides insights into used technologies and presents tools, components and services for advanced development, deployment and maintenance of devices.

Wireless sensor networks - new challenges in software engineering

Software development for wireless sensor networks requires novel programming paradigms and technologies. This article describes the concept of a new service oriented software architecture for mobile sensor networks. With this architecture, a flexible, scalable programming of applications based on an adaptive middleware is possible. The middleware supports mechanisms for cooperative data mining, self-organization, networking, and energy optimization to build higher-level service structures. The purpose of our research activities is the development of a framework, which radically simplifies the development of software for sensor network applications.

Service-Oriented Architectures for Embedded Systems Using Devices Profile for Web Services

A movement from distributed systems controlled by users to automatic, autonomous and self-configuring distributed systems is noticeable. Web services is one approach but lacking the secure integration of resource-constraint devices. This paper describes the devices profile for Web services (DPWS), underlying protocols and a DPWS toolkit implementation based on C and gSOAP and discuss its current state. It has enormous relevance for embedded systems and industrial automation since DPWS targets resource-constraint devices explicitly, and has the potential to shift the industrial landscape which is characterized of heterogeneous devices.

Beyond 6LoWPAN: Web Services in Wireless Sensor Networks

To date, Wireless Sensor Networks (WSN) require their own specific methodologies, tools, and technologies. With the rise of 6LoWPAN protocols (i.e., IPv6 over Low Power Wireless Personal Area Networks), WSNs can use IP to share a common network layer with other networks and the Internet for highly interoperable device communication. But additional efforts are necessary to develop new or adapt existing application layer protocols for IP-enabled WSNs. Hence, this paper investigates W3C SOAP Web Services (WS) in the context of WSNs. In particular, it is shown that the Devices Profile for Web Services (DPWS) can be used as an application layer protocol in WSNs.

Encoding and Compression for the Devices Profile for Web Services

Most solutions for Wireless Sensor Networks (WSN) come equipped with their own architectural concepts which raise the problem of possible incompatibility of computer networks and the WSN. Often gateway concepts are used to overcome this problem. But this is not the best solution on the long term. Other research fields and industrial domains are heading for universal cross domain architecture concepts based on internet technologies that are more mature and better understood. The IETF 6LoWPAN working group provides the groundings for standardized communication using existing network protocols like IPv6 also in low power radio networks. A big challenge when deploying further application layer network protocols on top of 6LoWPAN is the message size of existing mostly XML based protocols which does not meet the resource requirements of deeply embedded devices without further research efforts. This paper presents different data compression techniques for the Devices Profile of Web Services (DPWS) to be applied in 6LoWPAN networks. Therefore, we analyze a realistic scenario. We determined 18 message types in the scenario and compressed and encoded all messages by using existing schemes and tools. For the first time, we also investigate on the Efficient XML Interchange (EXI) format for DPWS.

WS4D: Toolkits for Networked Embedded Systems Based on the Devices Profile for Web Services

As the application of the Internet Protocol (IP) is not longer restricted to the internet and computer networks, future IP-based application scenarios require an enormous diversity of heterogeneous platforms and systems. Thereby emerging communication architectures, concepts, technologies and protocols must be capable of handling thousands of devices and communication endpoints on the one hand and be flexible and extensible enough on the other hand, to provide cross domain interoperability independent of platform specific constraints. The Devices Profile for Web Services (DPWS) is such a cross domain technology. This paper provides an overview of DPWS and existing DPWS implementations and toolkits with special focus on the Web Service for Devices (WS4D) initiative. Therefore, features and capabilities of DPWS are described in detail by referring to the open source WS4D implementations. The target platforms are ranging from resource rich server platforms down to highly resource constrained embedded devices.

Web services on deeply embedded devices with real-time processing

Service-oriented architectures become more and more important in connecting devices with each other. The main advantages of service-oriented architectures are higher abstraction level and interoperability of devices. In this field Web services become the most important standard for communication between devices. But this upcoming technology is only available on powerful devices. Embedded hardware is often excluded from the deployment of Web services because of the lack of resources like computing power and memory. In this area also real-time capabilities for process control are required. This paper presents a new approach to handle Web services communication on deeply embedded hardware with the devices profile for Web services specification.

Devices Profile for Web Services in Wireless Sensor Networks: Adaptations and enhancements

For Service-oriented Architectures, Web Services are claimed as state of the art to connect business execution layers as well as networking devices. Additionally, the deployment of Wireless Sensor Networks became applicable over the last years. The usage of application layer gateways and proxy concepts allow the integration of these sensor networks into real world scenarios and existing networks that make use of Web Services. This paper presents a new approach to adapt and enhance the Devices Profile for Web Services to be applied in Wireless Sensor Networks directly. Thus, seamless connectivity between business layers, device level networks, and Wireless Sensor Networks are possible.

Survey on real-time communication via ethernet in industrial automation environments

For companies in the automation industry, the development of real-time Ethernet to connect devices is of high economic interest to replace conventional fieldbus systems. Therefore, many approaches for adapting Ethernet to real-time requirements come from industrial applications. This is a challenging task as the original Ethernet standard IEEE 802.3 was not designed for real-time data transmission. Likewise, protocols basing on Ethernet like TCP, UDP, and IP do typically not consider real-time requirements. Hence, adaptations on several OSI layers become necessary to make the industrial system meet hard real-time requirements. For this purpose, a multitude of realtime capable Industrial Ethernet systems has been developed, which solve the problems of standard Ethernet- and TCP/IP- or UDP/IP-based communication in a variety of ways. This paper gives a summary of different Industrial Ethernet protocols for the real-time data transmission via Ethernet in automation environments. Advantages and disadvantages of these protocols are analyzed with regard to their sustainability in terms of their realtime capability, reliability, scalability, self-configuration of the network, and hardware requirements. Against the background of connected devices tremendously growing in number and computational power in the prospective “Industrial Internet”, consequences for future developments are drawn.