Christoph Niedermeier

High Quality Mobile Communication

Future communication environments have to support mobility at various levels ranging from device and personal to session and service mobility. Much effort is currently beeing spent in the areas of cellular access technology, wireless LAN technology and mobility support in IP (Mobile IP). There is a clear trend that the IP protocol is becoming the dominant networking protocol. Since standard IP networks do not provide any guarantees for the transmission quality parameters, there is a clear demand for a comprehensive QoS mechanism, which allows for adaptation in a mobile environment using heterogeneous devices with heterogeneous access networks.

A model based development approach for building automation systems

As of today, building automation systems are present in almost any commercial building. They perform climate control, lightning control, access control, surveillance, and quite a few other tasks. As a result of their evolutionary development, building automation systems are divided into separate silos of disciplines that are not well integrated with each other. As of today, a variety of communication protocols, data models and engineering approaches are used by different vendors. Existing standardized building automation protocols as BACnet or KNX allow integration of some disciplines on the communication level but fail to provide means for common description of devices, services and data on the semantic level. This means that building automation applications that span multiple disciplines require a high effort for development, engineering and maintenance. If devices from multiple vendors are integrated in one installation, a set of different engineering tools and vendor-specific knowledge is required. In the ITEA “Building as a Service” (BaaS) project we try to overcome these deficiencies and define a common way to develop, engineer, commission, operate and maintain building automation systems following a service oriented approach. The whole process will be supported by semantic models to reduce costs and time-to-market, which is a quite new approach. In this paper we will present the current state of the work with special regard to domain modeling and model driven processes that are currently being specified for the BaaS platform.

Connecting the web with the web of things: lessons learned from implementing a CoAP-HTTP proxy

The Constrained Application Protocol (CoAP) is a lightweight application layer protocol for the Internet of Things. CoAP is based on HTTP mechanisms to build RESTful Web services. In contrast to HTTP, CoAP was designed for machine-to-machine (M2M) communication and uses a binary representation. This allows efficient transport and processing in resource-constrained networks such as Wireless Sensor Networks (WSN). Due to the analogy to REST, a mapping between CoAP and HTTP is possible. In this paper one of the first translating CoAP-HTTP proxies is presented, that provides HTTP clients transparent access to CoAP resources and vice versa. Furthermore, caching relieves CoAP servers, which solves a key challenge for the Internet of Things: to allow a constant/permanent availability of resources from a network of constrained devices, which are required to minimize data transmissions due to their noticeable restrictions in power consumption. We describe, which issues of the translation we found during the time of implementation and testing, and explain how the proxy handles these issues. Finally, an evaluation, using real WSN hardware, is given, and an approximation scheme on how much transmissions can be saved by caching resources is provided.

TinyModules: Code module exchange in TinyOS

The ability to update or exchange the program code running on sensor nodes is a core requirement in many wireless sensor network scenarios. Such code update mechanisms must take the specific resource limitations of wireless sensor nodes into account since both the transmission and the processing of updates consume considerable amounts of time and energy. We present TinyModules, a novel code update mechanism for TinyOS-based sensor networks whose idea is to divide the program code into a static part and an exchangeable TinyModule. TinyModules is highly configurable with the system developer being able to freely define which parts of the application should be exchangeable. We show that the use of TinyModules can achieve considerable savings in terms of code update size and update time with only negligible additional processing required on the nodes.

Knowledge-based middleware for future home networks

Humans are lazy. They want to get as much support and assistance in their daily life as possible. To provide sophisticated digital butler functionality a system has to monitor the humans and their environment to understand their desires. It has to control all devices to translate the deduced wills into actions. To provide an integrated intelligent environment to the residents it is necessary to overcome the borders of different manufacturers, devices and access technologies. A management and control middleware is needed that shields users as well as high level management services from the technical details of the network of devices by providing a standardized, resilient and secure communication channel. We present a knowledge-based middleware as base for that purpose in this paper. The novel approach is the transparent connection of highly heterogeneous home devices by requiring only very limited functionality per device. Our design allows the desired high autonomicity in a secure and efficient way.

Towards a Service Oriented Architecture for Wireless Sensor Networks in Industrial Applications

Abstract We discuss the introduction of service oriented architectures to wireless sensor networks (WSN) in industrial applications. We give an example for a WSN architecture as applied in the EU project SOCRADES in order to explain constraints preventing a full-fledged service oriented approach. Such an approach appears to be beneficial for applications like diagnostics or monitoring where service composition can provide new functionalities. However, the limited resources in WSN must be taken into account. For control applications additional constraints like determinism or latency bound severly limit a loose coupling of services. As a consequence we propose a support by appropriate design and engineering tools.

SCOPE - Sensor Mote Configuration and Operation Enhancement

Wireless sensor networks are difficult to manage and control due to their large geographical distribution and the lack of visual feedback. Tasks of configuration, debugging, monitoring and role assignment are only possible with access to the running application. With SCOPE we developed a generic management framework for such networks. It can be integrated in every TinyOS application to monitor and adjust application values such as configuration variables, sensor readings or other data. To be most flexible a generic approach was taken to read and set variables by Remote Instance Calls. SCOPE is a demon application running on every mote and sending the desired data to a Java application on a PC with network access. This enables the system administrator to manage and control every single node by adjusting these values. This paper describes the architecture and use of the SCOPE framework as well as comparies it with other non-commercial state-of-the-art system management frameworks for wireless sensor networks.

Engineering and operation made easy - a semantics and service oriented approach to building automation

Building automation systems control many aspects of todays buildings - lightning control, air condition, shading, access control, and surveillance, just to name a few. This diversity and the diversity of related technologies and protocols entails that the extension or integration of building automation systems requires a major effort. To address these challenges, the ITEA3 Building as a Service (BaaS) project developed a reference architecture that is based on a service oriented approach enhanced with semantic descriptions that aims at model based code generation and simple integration of legacy devices. In this paper, we present an overview of the BaaS reference architecture with a specific focus on the information model and on the envisioned way to take advantage of the semantic descriptions for information filtering, search and discovery throughout the lifecycle of a building automation system.

A model of pervasive services for service composition

We propose a formal definition of a pervasive service model targeting the very dynamic environments typical of mobile application scenarios. The model is based on a requirement analysis and evolves from existing service definitions. These are extended with pervasive features that allow for the modeling of context awareness, and pervasive functionality needed for the dynamic (re-) composition of services. In order to demonstrate its value, we present an implementation of a pervasive service platform that makes use of the service model.