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Chapter 2. Related Work/Fundamentals 19

2.3. Home Automation Gateways

A gateway is a linking device between two or more diﬀerent network technologies. It provides

uniﬁed interfaces and protocol conversion methods to enable diﬀerent participants to communicate

with each other. The gateway implies an abstraction layer, as the participants do not have to

know details about the protocol and characteristics of the other side. A HA gateway is usually a

piece of hardware, consisting of a processing unit and diﬀerent interface modules. The complexity

depends on the number of supported systems as well on the systems themselves. There are a wide

variety of gateways, which can provide very diﬀerent functions. In this work, they will be divided

in two main categories:

HA-HA gateway: HA-HA gateways are focused on connecting diﬀerent HA systems among

themselves. Examples are X10RF to X10 or ZigBee to KNX [10] gateways.

HA-PC gateway: HA-PC gateways aim to incorporate computers into the automation system,

by providing interfaces like serial port, USB or LAN. Such gateways often support more than

one HA protocol in order to be applicable to many tasks and to address a high number of

potential buyers.

Connecting diﬀerent transmission technologies like KNX TP and KNX RF (section 2.2.4 on

page 9), allows the user to select the most appropriate system for each task. This combines

their advantages and leads to increased robustness. Furthermore, automation systems can be up-

graded with hardware from diﬀerent systems. This can be necessary if a product is discontinued

or a certain device does only exist for another HA system. Apart from that, gateways can have

typical computer interfaces, like Ethernet or USB, allowing much more extensive control possibili-

ties. The drawbacks are relatively minor compared to the advantages. Due to an additional device

in the information chain, some functions like signal repetition will cause a delay and increase the

latency of the whole system. Another point against the acquisition of a gateway is the price which

can increase up to several hundred euros for high class systems.

2.3.1. Example Gateways

This section will present some selected HA gateways. Since this work aims to integrate HA into

an Intelligent Environment, in which computers play a central role, only HA-PC gateways are

considered. They must be able to connect to 433 or 868 MHz wireless systems and should support

many diﬀerent protocols. It is also desirable that the device is low cost and easy to use. All the

four presented gateways fulﬁl these requirements and could be used for the practical part of this

work (chapter 3 on page 27 Concept).

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