Wednesday, 20. March 2013 20.03.13 09:09 Age: 5 Jahre

Intelligent Switches
Wireless, Efficient Building Control Systems

Prototype boards for light switches

In manufacturing plants and private home, intelligent building control systems are used to control numerous systems such as lighting, air conditioning and window blinds. To control the systems accordingly, network nodes transmit signals between the connected devices, usually through cables, until now. Radio controlled devices are also possible, but so far their ranges are very small and often possible in only one room.

Technical problems often arise in these installations: Nodes might disappear due to faults or remodeling, which hinders communication at that location. Malfunctions might occur due to dynamic changes, such as moving people or opening and closing doors. Interference from other devices on the same frequencies is also possible. When many devices are transmitting simultaneously, the signal volume is very large with many redundancies and the nodes interfere each other, leading to the broadcast storm problem. If an overload occurs, communication might even collapse completely. Intelligent building control systems are a very useful technology, but they do not work efficiently yet and installing them can be very complex, especially when signals are transmitted through cables.

Large networks incorporating many devices, with wireless installation – this is the goal of Junior Prof. Dr. Hannes Frey and his assistant Rafael Funke. The aim of their research is to minimize problematic redundancies by removing nodes, thereby thinning out the network. This type of system is more susceptible to malfunctions, but this problem can be overcome with the right balance between the network density and the freedom from redundancy.

Dr. Hannes Frey and Rafael Funke base their research on the conventional function method: Each node transmits a received signal to each of its neighbors exactly once. Despite a limited transmission range, this reaches all the devices in the network. Frey and Funke configure the system so that it can respond to disturbances dynamically: Special back-up nodes repeat the signal on backup paths if necessary, and only if necessary. With multi-hop communication this even works through non-existing devices. In addition, the nodes can function under low capacity (cost-efficiently) by using algorithmic solutions from the microcontroller.

Small circuit boards, developed and built by project partner Insta Elektro GmbH in Lüdenscheid, are installed in a conventional switch for each individual node. Besides switches, remote controlled devices and motion sensors can also be used as input devices.

The configuration has already been tested in experimental setups and simulations with 230 installed nodes. In their results, Hannes Frey and Rafael Funke reported a significant delivery rate increase of up to 95 percent, the portion of nodes that actually received the message.

The two-year research project was funded by the Federal Ministry of Economics and Technology with 180,000 euro as part of the Central Innovation Programme for SMEs (ZIM).

Junior Prof. Dr. Hannes Frey
Large Wireless Networks
Tel: 05251 60-5380