A variety of home and building automation technologies are currently in use in state of the art home and buildings and will be use for the next decades. The technologies are either scoped on certain domains of automation (e.g. lighting, shading, HVAC, security, safety, ...) or focus on specific geographically separated markets (e.g. Europe or North America).
Important technologies to be mentioned here are for example KNX, LonWorks, BACnet, ZigBee, Z-Wave or EnOcean. KNX is an important European home and building automation standard that is mainly used in the field level of a automation control network and a huge variety of devices and products exists. On the same level LonWorks provides similar features but has a higher market share in the North American marekt. BACnet on the other hand is an open standard that is mainly used in the automation level of a control network and is mainly in use for commercial building automation technologies. ZigBee is an open wireless standard that mainly focuses on wireless sensor networks and home automation. Another wireless standard for home automation is EnOcean, which recently gains more importance, since it uses energy harvesting for collecting the required energy to operate the automation devices. Z-Wave is a popular but closed standard that operates in a similar environment like ZigBee.
The huge heterogeneity of technologies is an inhibitor for the successful deployment of home and building energy management systems, which are an essential component for optimizing the energy consumption of a building and further for future interaction patterns found in smart grids or smart cities. In this domain also new protocols emerge like for example (Wireless) MBus that can be used to communicate with smart meters.
All these technologies come with a different system stack. For example, custom physical, data link, network, transport, session and application layers. In order to make them interoperable gateways are required that map the different communication principles of the different layers. For the integration a mapping can be provided either for each possible communication pair, or a single integration technology is chosen to which all other technologies are mapped.
The single technology integration approach is desirable since the complexity and the efforts can be reduced. The question is now which technology stack should be used for the integration. A strong trend in research and industry aims at using standard and mature Internet and IT technologies for the integration but also for new devices directly on the level of sensors and actuators.
Important technologies to be mentioned here are for example KNX, LonWorks, BACnet, ZigBee, Z-Wave or EnOcean. KNX is an important European home and building automation standard that is mainly used in the field level of a automation control network and a huge variety of devices and products exists. On the same level LonWorks provides similar features but has a higher market share in the North American marekt. BACnet on the other hand is an open standard that is mainly used in the automation level of a control network and is mainly in use for commercial building automation technologies. ZigBee is an open wireless standard that mainly focuses on wireless sensor networks and home automation. Another wireless standard for home automation is EnOcean, which recently gains more importance, since it uses energy harvesting for collecting the required energy to operate the automation devices. Z-Wave is a popular but closed standard that operates in a similar environment like ZigBee.
The huge heterogeneity of technologies is an inhibitor for the successful deployment of home and building energy management systems, which are an essential component for optimizing the energy consumption of a building and further for future interaction patterns found in smart grids or smart cities. In this domain also new protocols emerge like for example (Wireless) MBus that can be used to communicate with smart meters.
All these technologies come with a different system stack. For example, custom physical, data link, network, transport, session and application layers. In order to make them interoperable gateways are required that map the different communication principles of the different layers. For the integration a mapping can be provided either for each possible communication pair, or a single integration technology is chosen to which all other technologies are mapped.
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| Integration approaches |
So an integration based on an communication stack using IPv6 is desirable and for constrained wireless sensor networks 6LoWPAN can be an enabler to efficiently operate IPv6 even on most contrained wireless devices. Just a new application protocol would be not sufficient. Instead a complete system stack (so-called IoTSyS stack) is required that can be used to operate the Internet of Things and to provide interoperability amongst heterogeneous technologies.
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| Integration challenge |
For providing the upper layer technologies different protocols can be used and a communication based on Web service communication (HTTP + XML) is desirable due to the huge success within IT system integration. However, due to the resource demand (CPU, memorgy, bandwidth) these technologies are not suitable for a deployment in a constrained (wireless) control network with constrained nodes. Therefore, optimizations like the Constrained Application Protocol (CoAP) and Efficient XML Interchange (EXI) can be used to optimize the resource demand of these technologies and to make a deployment feasible. Finally, the application layer semantics need to be mapped into the communication stack. For home and building automation technologies BACnet/WS, OASIS Open Building Information Exchange (OBIX) and OPC UA provide the required information models to provide a common view on building automation systems. Due to the RESTful design of OBIX, which fits very well to the mapping of data point oriented automation systems, OBIX is chosen for providing the application layer semantics.
The final system stack can be seen below.
Within the scope of the research activities and the thesis novel protocol bindings to CoAP/EXI have been contributed to the OASIS specification.
For the creation of a gateway software that maps the different technologies the Java platform is chosen and the OSGI runtime environment in order to use a component-oriented software design.
The gateway uses so call protocol-bundles or drivers for direct communication with bus systems. For this purpose, new drivers have been developed (e.g. W-MBus) or existing open source libraries (e.g. Calimero for KNX, BACnet4J for BACnet,...) have been reused. Then, a common object model based on OBIX is mapped to these technologies and provides the representation of the different systems for the Web service based communication interfaces and for internal services.
A proof of concept implementation for an integration gateway is provided at the project repository (http://code.google.com/p/iotsys).
More details about this approach can be found within the papers:
Markus Jung, Jürgen Weidinger, Christian Reinisch, Wolfgang Kastner, Cedric Crettaz, Alex Olivieri, and Yann Bocchi. A transparent IPv6 multi-protocol gateway to integrate Building Automation Systems in the Internet of Things. In Proceedings of the IEEE International Conference on Internet of Things (iThings 2012), Besancon, France, November 2012
Markus Jung, Jürgen Weidinger, and Wolfgang Kastner. A seamless integration of KNX into Constrained RESTful Environments. In Proceedings of the KNX Scientific, Las Palmas, Spain, November 2012
Markus Jung, Jürgen Weidinger, Wolfgang Kastner, and Alex Olivieri. Building automation and smart cities: An integration approach based on a service-oriented architecture. InProceedings of the 27th IEEE International Conference on Advanced Information Networking and Applications, Barcelona, Spain, March 2013.
The final system stack can be seen below.
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| IoTSyS system stack |
For the creation of a gateway software that maps the different technologies the Java platform is chosen and the OSGI runtime environment in order to use a component-oriented software design.
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| Integration gateway design |
More details about this approach can be found within the papers:
Markus Jung, Jürgen Weidinger, Christian Reinisch, Wolfgang Kastner, Cedric Crettaz, Alex Olivieri, and Yann Bocchi. A transparent IPv6 multi-protocol gateway to integrate Building Automation Systems in the Internet of Things. In Proceedings of the IEEE International Conference on Internet of Things (iThings 2012), Besancon, France, November 2012
Markus Jung, Jürgen Weidinger, and Wolfgang Kastner. A seamless integration of KNX into Constrained RESTful Environments. In Proceedings of the KNX Scientific, Las Palmas, Spain, November 2012
Markus Jung, Jürgen Weidinger, Wolfgang Kastner, and Alex Olivieri. Building automation and smart cities: An integration approach based on a service-oriented architecture. InProceedings of the 27th IEEE International Conference on Advanced Information Networking and Applications, Barcelona, Spain, March 2013.
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