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Chapter 2. Related Work/Fundamentals 9

control of home appliances over the existing power grid. X10-based devices are inexpensive and

easy to install and are therefore very popular, especially in North America. Power line Commu-

nication (PLC) oﬀers good ﬂexibility, allowing the user to relocate their devices to some extent.

Nevertheless, X10 is not as ﬂexible as comparable wireless systems, since the device must be

placed near power plugs. This excludes mobile devices, such as remotes or identiﬁcation tags. As

a result of this limitation, there is a wireless standard called X10RF. It is based on X10 and both

systems can be connected by using gateways. X10RF is mainly used by outdoor devices, such as

motion sensors or door bells for areas, where no power line is accessible. However, the core of

the automation system, which includes all actuators, still uses PLC. There are many diﬀerent X10

products on the market, but they can be divided into three main categories:

• Home Automation (switches, timers, shutter motors)

• Security (cameras, motion sensors, glass breaking sensors)

• Multimedia (universal remote, IR receiver)

Despite the wide product range, X10 suﬀers from many disadvantages: On the one hand, data

transmission is very slow

, which results in a noticeable delay between actions. The use of gateways

or signal repeaters that are used to extend the range of the systems, increases this delay; as a

result time lags up to 1 s are not uncommon. On the other hand, the X10RF protocol is not very

scalable and due to the binding to the slow X10 PLC, it is not likely that X10RF is capable of

asserting itself.

KNX/EIB

KNX is an open communication standard for home- and building automation (ISO/IEC 14543,

CENELEC EN 50090, CEN EN 13321-1, GB/Z 20965) and a derivate from the European In-

stallation Bus (EIB), BatiBus and European Home System (EHS). It speciﬁes how to connect

the diﬀerent KNX components and describes the protocol and the communication. About 200

companies worldwide distribute over 6000 KNX products [9], resulting in a huge product range.

The emphasis is on HVAC products, but there are also many solutions available for multimedia

and other ﬁelds of application. KNX components are highly priced and due to their relatively com-

plex installation, they are used primarily in new buildings. However, the ability to integrate other

automation systems allows the user to upgrade the system with easy to install wireless devices.

Lee et al. [10] developed a ZigBee-KNX gateway to interface both systems and to enable inte-

gration of both wireless and wired HA systems. Another approach is presented by Windhab [11],

where a Java-based software is used to control KNX devices via mobile devices, using Bluetooth.

Furthermore, special gateways such as Miele@Home allow connections to dishwashers and wash-

around 20 bit/s

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