What is Interoperability in the context of Demand Response?

Recent advances in wireless networking and microelectronic fabrication have enabled a mass production of low-cost computationally capable miniature devices that are already changing the way we live and communicate having the profound impact on our daily life. With such large number of different technologies, that coexist at the same space and time, one of the crucial questions is how to make them work together and provide more values for the end users.

Interoperability is defined as the ability of a system to work with or use the parts of equipment of another system. In the context of RESPOND project, the architecture of the system is designed to support interoperability from the beginning. RESPOND project aims to complement and enhance the existing smart home and building management systems, in order to improve the energy efficiency and optimize the costs by seamless integration of cooperative Demand-Response programs. Since there potentially exist different legacy and mutually incompatible devices, one of the most important goals is to ensure interoperability which represents one of the main pillars for the successful deployment of the RESPOND system. In particular, the interoperability will ensure that the developed system is future proof, with more choices regarding compatible hardware, and without undesirable vendor lock-in effect.

In order to categorize different features that contribute to interoperability, a layered interoperability model is presented, as shown in the Figure above, which comprises the common interoperability layers: technical, syntactic, and semantic layers:

  1. The first one – technical interoperability layer focuses on establishing communication channel between the systems. It represents the lowest level of interoperability that is required to hold for the system to be interoperable at all. It includes a combination of software and hardware that enables the physical communication channel and the lower layer of the protocol stack.  For home automation, TCP/IP is considered as the solution for technical interoperability. Nevertheless, home automation devices often lack hardware/software support for TCP/IP communication. Therefore, in order to provide technical interoperability for legacy home automation devices, it is necessary to employ appropriate hardware solution.
  2. Next, the syntactic interoperability layer enhances the interoperability by introducing a common data format for the message exchange between different systems. This interoperability layer empowers two or more systems with the capability to interpret the message content of exchanged data. There exist different methods for implementing syntactic interoperability. It can be performed directly between two or more devices using their native protocols, or by employing protocol converters. For the purpose of interoperability in RESPOND project, it will be implemented in a middleware, through protocol adapters that abstract diverse protocols of legacy and newly installed equipment and unify the data via CDM.
    The benefit of such approach is that each protocol needs to beconverted only into common format and back, that results in a linearly growing number of adapters (2N).
  3. Finally, on the semantic interoperability layer, the data are presented semantically, categorized using context ontologies and linked to other semantic data. Semantic interoperability is concerned about the meaning of the data and sharing of that meaning. It ensures that the precise meaning of exchanged information can be understood by any other application that was not initially developed for that purpose. In such a way, systems are able to combine received information with other information resources (e.g. ontology) and to process it in a meaningful manner.

To conclude, the interoperability represents one of the main foundational elements for the future Internet of Things that will undoubtedly change the way we live, work and communicate. Achieving interoperability at this point is not trivial, especially since IoT area is still in its infancy, and many lessons needs to be learned. Nevertheless, the significant market potential and possible societal benefits are expected to further push the development of interoperable standards towards achieving fully interoperable solutions for the benefit of all of us.

Lazar Berbakov, PhD
Research Associate


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