Home Automation

Chapter 2

Home Automation

Home automation (or domotics) is a practice of enhancing the household ap- pliances automation in residential dwellings, in order to allow features that were impossible or highly expansive in the past. Home automation, together with building automation, is born during the third industrial revolution, as an application of informatic technologies in house or building environments. Home automation aims to:

• enhance the life quality,

• enhance the house security,

• reduce the power consumption,

• reduce the maintainance costs.

A household appliance having computing and communicating capabilities is called a smart device (or smart appliance). Normally, smart devices are li- kely not to have big computational resources. Home automation has to deal with this problem with ad-hoc solutions and, very often, ad-hoc communica- tion protocols. Home automation functionalities include and extend those of building automation, such as the control of closures devices, lighting devices, HVAC devices and security and surveillance systems. In addition, home auto- mation provides for more house-specific services, such as the control of home entertainment systems, pet feeding or domestic robots.

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From the point of view of intelligence distribution, three possible architec- tures are possible in a home automation application.

1. Centralized architecture. Smart devices are not more than sensors and/or actuators. A centralized node coordinates the smart appliances and gene- rates the opportune orders.

2. Distributed architecture. There is no central intelligence point. The intelli- gence of the system is distributed among the devices that cooperate with each other in order to fulfill the service.

3. Mixed architecture. There is a central control point, but smart devices are also capable of cooperating independently with each other for some tasks.

This thesis work focuses on centralized architecture. The central control point may be a personal computer or a dedicated hardware with some computational resources.

The most used communication mediums in home automation are electrical wiring and radio frequency. Electrical wiring offers higher bit-rates but requires higher installation costs. The idea is using already installed cable networks, for example energy supply or telephony networks, in old houses, whereas installing new ad-hoc networks for new houses. On the contrary, radio frequency offers very cheap installations and low bit-rates. The radio frequency solution is the most followed in last years, for old houses as well as for new ones.

Another key requirement, especially for wireless-based home automation, is battery saving. Battery-powered smart appliances must have a very low power consumption, both for computing and communicating functionalities, in order to increase batteries’ lifes. Good battery consumption levels are considered those which permit years-long batteries lifes.

This thesis work uses IEEE 802.15.4[7] standard protocol in order to provide

wireless, low-cost, ultra-low-battery consuming home automation solutions.