Framework for Building Situation-Aware Ubiquitous

Services in Smart Home Environments

vorgelegt vonDiplom-Informatiker

Andreas Rieger

Von der Fakultät IV – Elektrotechnik und Informatikder Technischen Universität Berlin

zur Erlangung des akademischen GradesDoktor der Ingenieurwissenschaften

Dr.-Ing.

genehmigte Dissertation

Promotionsausschuss:Vorsitzender: Prof. Dr. habil. Odej KaoBerichter: Prof. Dr. habil. Sahin AlbayrakBerichter: Prof. Arkady Zaslavsky

Tag der wissenschaftlichen Aussprache: 31.05.2011

Berlin 2011

D 83

Zusammenfassung

Die zunehmende Verbreitung des Computers in verschiedenen Lebensbereichen er-

laubt neue Möglichkeiten der Nutzung, bringt aber auch Herausforderungen für Wis-

senschaftler in verschiedenen Fachrichtungen der Informatik. Mit Hilfe vernetzter

Geräte können intelligente Umgebungen geschaffen werden, die die Benutzer in auf

unterschiedliche Weise unterstützen. Die voranschreitende Miniaturisierung von Sen-

soren und Aktoren, die in Geräte des täglichen Lebens integriert werden, ermöglichen

einen allmählichen Paradigmenwechsel in Richtung des “Ubiquitous Computing”.

Insbesondere unsere eigene Wohnumgebung gerät dabei immer mehr in den Fokus.

Wohnungen und ganze Häuser werden zu so genannten Smart Homes. Ziel dieser

Smart Homes ist die Unterstützung der Bewohner hin zu mehr Komfort, Sicherheit

und Energieeffizienz. Vielfältige Technologien unterstützen diesen Ansatz, jedoch

fehlt es bisher an einem einheitlichen Framework, welches die sich dadurch ergeben-

den Herausforderungen adressiert. Die Integration verschiedenster Geräte, die unter-

schiedliche Kommunikationsmedien und Protokolle verwenden, die Erfassung von

Informationen aus der Umgebung und deren aufbereitete Bereitstellung, sowie die

Generierung von intuitiv bedienbaren Diensten sind dabei die wesentlichen Heraus-

forderungen.

Diese Dissertation befasst sich mit der Erforschung, Entwicklung und Evaluierung

von kontextsensitiven, allgegenwärtigen Diensten für Smart Homes. Dazu wurde

eine eingehende Analyse des Marktes, der Technologien und der Anwendungsgebi-

i

ete für allgegenwärtige Dienste für Smart Homes vorgenommen. Darauf basierend

wurden drei Hauptkomponenten identifiziert, deren Bereitstellung die Umsetzung

von solchen Diensten unterstützt. Diese Komponenten verringern die sich ergebene

Komplexität für Softwareentwickler und ermöglichen eine Fokussierung auf service-

spezifische Aspekte.

Die “Device Management”-Komponente stellt dabei ein transparentes, funktionales

Modell der darunterliegenden Geräte einer Smart Home Umgebung dar. Sie inte-

griert verschiedene Technologien und Protokolle und stellt diese über eine Abstrak-

tionsschicht den darüber liegenden Diensten zur Verfügung. Ein Kontext- und Situa-

tionsmodell stellt Umgebungsinformationen in einer standardisierten Form dar. Die

Einführung des Situationsmodells, welches analog zum menschlichen Prozess der

Erkennung und Bewertung von Situationen umgesetzt wurde, stellt den Diensten auf-

bereitete Situationsinformationen zur Verfügung, die für Adaption von Diensten und

Benutzerschnittstellen verwendet werden können. Die dritte Komponente stellt ein

Framework zur Bereitstellung von intuitiven, multimodalen Benutzerschnittstellen

für Smart Homes dar. Basierend auf einer abstrakten, modellbasierten Beschreibung

der Benutzerschnittstellen werden diese an die Situation des Benutzer und der ak-

tuellen Umgebung angepasst und ausgeliefert.

Die Implementierung wurde u.a. im Rahmen des Service Centric Home Projektes

durchgeführt und in eine Smart Home Testbed integriert. Verschiedene Dienste aus

dem Bereich Smart Home wurden implementiert und in das Testbed integriert. Dabei

konnten die Dienste und deren Entwicklung von den verschiedenen Komponenten

der Architektur profitieren.

ii

Abstract

The increasing spread of computing technology in different areas of life brings with it

new possibilities but also challenges for scientists in various disciplines of computer

science. With the help of connected devices we can create smart environments that

assist the user in many ways. The miniaturization of sensors and actuators that are

integrated into everyday devices enable a gradual paradigm shift in the direction of

"ubiquitous computing".

In particular, our own living environment increasingly becomes the focus of our atten-

tion. Flats and houses become so-called smart homes. The goal of these smart homes is

support the inhabitants to more comfort, safety and energy efficiency. Multiple tech-

nologies support this approach; however, there is a lack of a unified framework that

addresses the challenges. The key challenges are the integration of different devices

using different communication technologies and protocols, the acquisition of informa-

tion from the environment and their aggregated provisioning, and the generation of

intuitively usable service.

This dissertation is concerned with research, development and evaluation of situation-

aware ubiquitous services for smart homes. We have performed an in-depth analysis

of the market, the technologies and application areas for ubiquitous services for smart

homes. Based on this analysis we have identified three main components for the im-

plementation of smart homes, supporting the implementation of ubiquitous services.

These components reduce the resulting complexity for software developers and focus

iii

attention on service-specific aspects.

The device management component thereby offers a transparent, functional model

of the underlying devices in a smart home environment. It integrates various tech-

nologies and protocols and provides an abstraction layer for the available services. A

context-and situation model provides information about the environment in a stan-

dardized form. The introduction of a situation model, which was developed analo-

gously to the human process of detection and assessment of situations, provides pro-

cessed situation information for services, which can be used for adaptation of services

and user interfaces. The third component provides a framework for the provision of

intuitive, multimodal user interfaces for smart homes. Based on an abstract, model-

based description, user interfaces are adapted to the situation of the user and the cur-

rent environment and delivered.

The implementation was done inter alia on the Service Centric Home project and inte-

grated into a smart home testbed. Several smart home applications have been imple-

mented and integrated into the testbed. This way, the services and their development

could benefit from the various components of the architecture.

iv

Acknowledgments

The completion of my dissertation has been a long journey. It is true that “Life is what

happens to you while you’re busy making other plans”. I stopped counting the many

times I have been questioned whether I have have finished my PhD project yet. Many

things happened and changed while I was involved with this project. Even though my

dissertation has always been a priority, due to planned, motivating, exciting, but also

unexpected, disturbing, and bad challenges in personal and work life my dissertation

could not always be the number one priority. Without the continuous support of the

select few that I’m about to mention, I may not have gotten to where I am today.

I’d like to give special thanks to my advisor Prof. Sahin Albayrak for the great sup-

port and motivation and for giving me the opportunity to conduct my research in

the exciting environment of the DAI-Labor of the Technische Universität Berlin. He

gave me the opportunity to work with and lead the competence center Next Genera-

tion Services (NGS), providing the basis for my research. I would also like to thank

Prof. Arkady Zaslavsky for his motivating support and feedback as member of the

committee. His feedback helped to greatly to improve my thesis.

This work has been conducted as part of the research of the NGS group. All current

and former team member, in particular Marco Blumendorf, Richard Cissee, Grzegorz

Lehmann, Dirk Roscher, Frank Trollmann, Sebastian Feuerstack, Jens Wohltorf, and

every other which was not mentioned, made a direct and indirect contribution to this

work for which I’m greatly thankful.

v

And last but not least I’d like to thank my parents for their unflagging belief, their

constant source of support, and for always being there for me. This thesis would

certainly not have existed without them.

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viii

Contents

1. Introduction 3

1.1. Ubiquitous Computing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2. Motivation and Problem Description . . . . . . . . . . . . . . . . . . . . . 5

1.3. Terminology and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4. Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.5. Structure of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2. Smart Homes 13

2.1. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.2. Market analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.3. Application areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2.4. Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5. Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3. Literature Review 49

3.1. Ubiquitous Computing / Pervasive Computing . . . . . . . . . . . . . . 49

3.2. Smart Home projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

3.3. Context- and Situation Awareness . . . . . . . . . . . . . . . . . . . . . . 58

3.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

4. CoSHA - Conceptual Smart Home Architecture 69

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Contents

4.1. Requirements analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4.2. Conceptual architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

4.3. Device Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

4.4. Context and Situation-Awareness . . . . . . . . . . . . . . . . . . . . . . . 80

4.5. User Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

5. CoSHA Implementation 93

5.1. Device management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

5.2. Context model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

5.3. Multi-Access Service Platform . . . . . . . . . . . . . . . . . . . . . . . . . 102

5.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

6. CoSHA Evaluation 111

6.1. Smart Environment Testbed . . . . . . . . . . . . . . . . . . . . . . . . . . 111

6.2. Service Centric Home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

6.3. Smart Home Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

6.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

7. Conclusion and Future Work 135

7.1. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

7.2. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

A. Outcomes of the dissertation work 139

A.1. Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

A.2. List of talks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

List of Figures 143

List of Tables 147

References 149

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Contents

2

1. Introduction

“The most profound technologies are those that disappear. They weave

themselves into the fabric of everyday life until they are indistinguishable

from it.” - Weiser, 1991

1.1. Ubiquitous Computing

Almost 15 years ago Mark Weiser described in his vision of ubiquitous computing com-

puter systems that will disappear into the environment of our daily lives, and comput-

ing infrastructure as a tool that is available everywhere, every time, and to everybody.

Weiser believes that computing technology will evolve into everyday life and will be

as natural as today’s non computing technologies like writing on a piece of paper with

a pencil. These changes will lead to new environments saturated with computing and

communication capabilities, yet having devices and appliances integrated into the en-

vironment such that they disappear from the user. By the time of his writing, technol-

ogy didn’t allow the realization his vision in an appropriate form yet. However, his

work was a starting signal for many researches to explore a new paradigm of comput-

ing systems. Nowadays, ubiquitous computing is still an ongoing research area with

many unsolved research questions. Many prototype applications have been built, but

less have evolved into commercial systems. Due to the continuously advancing avail-

ability of computing and network infrastructure, the potential audience of computing,

3

1. Introduction

communication or other services of informational nature is growing steadily. Smaller

processors, embedded into everyday objects with increasing processing and commu-

nications abilities can build the foundation for the evolution of ubiquitous computing

systems. These technological changes will have a strong influence in the way we in-

teract with computing systems. Explicit usage of applications and services will fade

into the background, while services running in the background will come to the fore,

but without clear perceiving the use of these services. Given the advances in the fields

of distributed computing, sensor networks, and middleware, the area of ubiquitous

embedded computing is now being envisioned as the way of the future. The systems

and technologies that will arise in support of ubiquitous embedded computing will

undoubtedly need to raise a variety of issues, including human-computer interaction,

dependability, autonomy, resource constraints, etc. In a ubiquitous computing world,

service provisioning systems will be able to proactively address user needs, negoti-

ate for services, act on the user’s behalf, and deliver services anywhere and anytime

across a multitude of networks and devices. As a result of the development humans

benefits from the use of technology without having to consider in a specific situation,

whether and how she will use the technology. The use of technology gets more or less

unconsciously.

These days the vision of ubiquitous computing is increasingly becoming reality, as

Moore’s law about a long-term trend in the history of computing hardware, in which

the number of transistors that can be placed inexpensively on an integrated circuit

has doubled approximately every two years, continues to pertain. The capabilities of

many digital electronic devices are strongly linked to Moore’s law, leading to smaller

sensors and inexpensive devices with more processing capabilities. Nowadays mobile

phones have not only the ability to act as a mobile communication device, but also as a

universal personal assistant. They are capable of storing and accessing different types

of information, as well as extending their usage by the use of internal or external sen-

4

1.2. Motivation and Problem Description

sors. GPS, compass, and accelerometer are just three of the most common today. They

allow not only having services like turn-by-turn navigation on the phone, but allow

also the seamless integration of mobile phones into a bigger service and communi-

cation infrastructure, where the mobile phone acts only as a part of a larger system.

Such an interconnection of sensors and devices shows how technology allows us the

realization ubiquitous computing scenarios.

With all that technological advances, ubiquitous computing is already a partial part of

our daily life. We start using mobile communication nearly anywhere and anytime.

The usage of small sensors in our devices, e.g. GPS in mobile phones or cameras,

works automatically, mostly without taking notice of it. We experience the use of

that technology later, when take note of the online photo service knowing the location

where the picture was taken. However not all challenges of ubiquitous and invisi-

ble computing mentioned by (Schilit et al., 1993) have been met yet. Heterogeneous

devices and networks, interoperability among disparate entities, and mobility and se-

curity are still a challenge for researchers (Kumar and Das, 2006).

1.2. Motivation and Problem Description

Technology plays a more and more important role in our lives. We start to use tech-

nology for an increasing number of tasks of our daily activities. On the other hand

devices that we use tend to get more and more complicated, the consequence of being

that we do not make use of all the possibilities the devices are offering. Almost every

mobile phone for example can be used for more than making calls and sending texts.

There are of course users that make use of the camera, the integrated calendar, the pos-

sibility to receive emails or install new applications, but many users are overwhelmed

and don’t make use of the possibilities, even if they might be useful for them.

Our homes combine appliances and technology of different branches and vendors,

5

1. Introduction

each of which may have been acquired at different times (Edwards and Grinter, 2001).

Basic approaches for new smarter technology are mostly isolated applications. Appli-

ances in our homes get more and more capabilities too. Each individual appliance is

equipped with computing power. Yet also much potential remains unused, as the de-

vices cannot communicate with each other. If at all only devices from the same branch

or the same manufacturer can communicate and exchange information. A manufac-

turer of white goods interconnects his devices resulting in the possibility to read off

the fridge if the dishwasher has finished. Yet it is not possible for the user receive the

information on her mobile phone or as a subtle note on the TV screen while watching

a thrilling blockbuster. Hence it is an important research problem how we can easily

interconnect devices and applications of different heterogeneous sources. It is even

essential to integrate new technology next to existing older systems without making

the old ones unusable (Pensas and Vanhala, 2010).

Technological advances help us realizing smart environments. Smart environments are

defined as “one that is able to acquire and apply knowledge about the environment

and its inhabitants in order to improve their experience in that environment” (Cook

and Das, 2007). Yet, our homes will not turn into smart homes until the potentials of

the technology will get used. Smart environments and smart homes remain an open

research area (Schmidt, 2010) as the impact of technology in these areas is less domi-

nant than in mobile computing or personal computing devices. A main goal of smart

homes is to make quality of living at home better. Everyday activities should get more

intuitive, more enjoyable, more convenient, safer, easier, faster, and better in many

other ways (Saizmaa and Kim, 2008). Real-time and real life issues like continuous

availability, extensibility, resource efficiency, safety, security or privacy (Nehmer et al.,

2006; Becker, 2008) are major challenges for such systems.

One of the primary technological challenges for ubiquitous computing noted by Weiser

is the issue of context management, that is, the need for methods of managing and co-

6

1.3. Terminology and definitions

ordinating the flow of information between the nodes and services available in a ubiq-

uitous environment. The ubiquitous interface envisioned by ubiquitous computing re-

quires that devices continuously support the user’s current actions; context-awareness

forms the basis of this capability. Context-awareness uses context information to pro-

vide relevant information and/or services to the user, where relevancy depends on

the user’s task (Dey, 2000). Context information consists of information about the en-

vironment, the user and their current task(s). Offering this information in a formatted

way, e.g. as a context model, to the service running in the environment allows these

services to provide context-aware information. Ubiquitous services can then seam-

lessly integrate and cooperate in support of user requirements, desires and objectives.

Context-aware services integrate context information to make applications and ser-

vices to be more user-friendly, flexible, and adaptable (Jang et al., 2001).

1.3. Terminology and definitions

In the following we provide some definitions of the terms that are often used within

our research.

1.3.1. Context-Awareness

Context-Awareness describes applications and services that are aware of their environ-

ment that they are running in. They make use of this information to run differently

in varying environmental conditions. This usually involves three steps: collecting,

representing and reasoning. Information about the environment is collected usually

via sensors but also via explicit user input. The collected information is being pre-

processed and stored in a common format. Based on that representation reasoning

algorithms interpret the information. All this together forms the basis for adaptation

of applications and services in a smart home environment.

7

1. Introduction

1.3.2. Situation-Awareness

Situation-Awareness is built on top of Context-Awareness. While the latter does only a

limited interpretation of context information, the former tries to conclude real life sit-

uations form context information. Therefore understanding how information, events,

actions, and the intention of the user will impact goals and objectives in the future will

be used to evaluate situations from context information.

1.3.3. Smart Home

The term smart home describes homes equipped with “intelligent” technologies that

generate an added value for the inhabitant. Usually smart homes are privately used

homes (e.g. home, apartment) in which the many home automation devices (such

as heating, lighting, ventilation), home appliances (such as refrigerator, washing ma-

chine, dryer), consumer electronics and communications equipment are interconnected

and oriented towards the needs and demands of the user. The interconnection allows

the provisioning of new services and assistance functionalities that go beyond the in-

dividual value of the home’s appliances.

1.3.4. Adaptation

Adaptation is the logical use of the properties context-awareness offers. Adaptation

can take place in several ways. First, services themselves can be adapted. This means

that the services conduct related to their usage situation in different ways. Second, the

user interface can be adapted to the current context. The performance of the service

remains untouched, but the adaptation of user interfaces for improved inter-location

allows the services. They may include graphic enhancements also take a change of

rules to a more intuitive, more natural or more appropriate situation to allow interac-

tion.

8

1.4. Contribution

1.4. Contribution

We started our work with analyzing research in ubiquitous computing and context-

awareness. The vision of ubiquitous computing is still the motivating force for many

research projects. Yet, many issues remain unresolved. We have chosen the home

environment as the focus of our research. It provides ideal conditions for research

focusing on how to support the user best with technology that disappears from the at-

tention of the user. The analysis of technologies that are commonly used for realizing

smart home solutions showed a general heterogeneity among devices and communi-

cation protocols. This led our research to the first problem: how the integration of

heterogeneous devices should be handled.

Based on our findings and based on related work in that area we have proposed a

conceptual architecture for building situation aware services for smart home environ-

ments. The architecture addresses three main different research topics that we have

identified for developing services for smart homes:

• Integration of heterogeneous device

• Situation aware adaptation of services

• Intuitive and multimodal user interfaces

We have developed an abstract device model that allows integration of heterogeneous

devices with different communication technologies, protocols and APIs. Abstract

mapping of underlying functionality to functional properties allows service devel-

opers to focus on features rather than on specific implementation issues of used tech-

nologies. It is possible to handle the devices without knowing their device-specific

functionalities when creating services that make use of device specific functionalities.

Our context model offers a basis for automated processing of the environmental state.

The usage of Hidden Markov Models in our approach extends current context-aware

9

1. Introduction

approaches and allows us to find situations that match the current human mental state

during a sequence of interactions with the environment (Rieger and Albayrak, 2010).

We have developed a user interaction framework that generates multimodal user in-

terfaces. Using abstract models for description of user interfaces allows adaptation of

user interfaces based on the current situation of the user or device characteristics of

the device (Rieger et al., 2005).

Based on the conceptual architecture we developed several ubiquitous services with

focus on specific parts of the architecture. These services where carried out in testbed

for smart home services. We have created this testbed in order to allow evaluation of

ubiquitous services for smart environments in a real smart home environment. Var-

ious home automation technologies and interaction devices have been integrated to

support different application areas.

1.5. Structure of the Thesis

This thesis is structured as follows: In the following chapter we describe smart homes

in general, the market of smart homes, their application areas and technologies. Based

on this general overview we identify challenges as well as existing barriers for realiz-

ing smart home solutions.

10

1.5. Structure of the Thesis

Figure 1.1.: Structure of the thesis

Thereafter a literature review shows other smart home research projects. In addi-

tion we take a look at research activities in ubiquitous computing and context- and

situation-awareness, which form the basis for many smart home services.

Based on a requirement analysis we describe “CoSHA”, our conceptual architecture

for smart homes in the chapter thereafter. We identify three main requirements that

support the development of smart home services; easy integration of devices, a context-

and situation model as basis for adaptation, and a user interface framework that sup-

ports multimodal interaction.

Afterwards, in chapter 5, we describe the implementation of our main components.

A device model allows transparent integration and access of heterogeneous devices

and their data by services. The context model stores sensed information and allows

derivation of usage situations. The usage of the situation model to derive intentions of

the user has been published in (Rieger and Albayrak, 2010). A framework for deliver-

ing multimodal user interfaces acts as the central component for providing interaction

11

1. Introduction

between the user and her environment.

The second last chapter describes the evaluation of our approach with several proto-

type applications in a real life testbed for smart homes. The described BerlinTainment

application has been published in (Wohltorf et al., 2005; Rieger et al., 2005).

In the final chapter we summarize our work in the conclusion and present an outlook

about open challenges that might be a starting point for future research.

12

2. Smart Homes

The area of smart homes has attracted significant attention as a specific area within

the research of ubiquitous computing. Smart homes have been defined as

“domestic environments in which we are surrounded by interconnected

technologies that are, more or less, responsive to our presence and actions”

(Edwards and Grinter, 2001).

A smart home can be an apartment or house equipped with sensors, user interfaces,

actuators, networks, and data and decision fusion modules to offer helpful services to

its occupants. Such services can often adapt to the preferences of the user through a

period of observing or interacting with the user.

Until now, most homes offer only little technological support for the user. Often the

term smart home is used to refer to homes that use simple automaton tasks based on

temperature measurements or time constraints. Simple installations that turn off the

lights in a room, after the last person left the room or automatic blinds that close at

night and open again in the morning is two examples. These blinds work standalone,

taking into account only the current time and a simple trigger as a factor of operation.

They close, even if the occupants are outside in the garden and closing might lock

them out. In the blind control application the operation can be made smart if the oper-

ation takes into account other information from door sensors and activity monitoring

and remembering the setting for the same or similar conditions in the future.

13

2. Smart Homes

One important point that turns regular homes into smart homes is the interconnec-

tion of various devices and appliances through a communication network. This al-

lows home appliances, consumer electronic devices, and communication devices to

turn into smart devices that follow the needs and demands of the inhabitants. In or-

der to leverage the capabilities of these devices, new services have to be offered and

deployed into smart homes. These services will be able to improve the quality of life

through manifold assistance in daily activities. Devices, systems and technologies will

be used to create more comfort, flexibility, energy efficiency, and security.

Future solutions will sense the presence of a person in a room and conclude the situa-

tion and context of the user to support her better. A smart home could automatically

set the appropriate lighting, switch on the heating to a warm and comfortable tem-

perature, and tune in to the favorite music station or television channels, taking into

account the situation and goals of the user. Another example is an automated lawn

sprinkler that not only gains efficiency through the use of moisture sensors in the

ground, but also by the use of the weather forecast from the internet.

2.1. Roles

A smart home environment is characterized by three main roles. The first and most

obvious one is the user. In a smart home environment this is typically the inhabitant

and her family members. In some scenarios also guests cannot be ignored. The sec-

ond and not rather important role is devices. Devices allow the realization of smart

homes and are the interface to the inhabitant. The third main role is services. Services

provide the intelligent functionality for the inhabitants and make use of devices in the

environment.

14

2.1. Roles

2.1.1. User

Smart home solutions are tailor made for the inhabitant of a home. Devices, appli-

ances and services are based on her preferences. Access to the services is granted to

each family member. Based on individual properties, different parts of the system are

available after the system knows the current user.

If a smart home system gets an integral part of a home that includes every task in a

home, one must not forget another special kind of user: the guest user. Certain well

known tasks from today’s homes need to be accessible for guest users also. Turning

on the lights should not require any explanation for example.

Interaction with the services should be adapted to preferences of the user. Left-handed

users might want to experience a different layout of interaction on a touchscreen than

right-handed users.

2.1.2. Devices

In today’s homes a multitude of devices exist already as shown in Figure 2.1. Un-

til now, these devices usually work standalone, in their specific application area not

producing any added value through interconnection with other devices.

Devices of a smart home can be divided into different categories:

White goods: Devices like fridge, drier, or kitchen equipment. Studies Franz et al.

(2006) show their potential for optimizing and reducing the energy consumption.

From the users’ perspective, the usage time of these devices is flexible under certain

restrictions, allowing services to take a certain amount of control over the operation of

these devices.

Until now, these devices are usually not connected to other devices. These devices

start to become networked and assistive services allow now possibilities of operation

15

2. Smart Homes

of these devices. There have been some commercial available products from Siemens

(“serve@home” series) or Miele (“miele@home” series). Until now, these devices were

more technology demonstrators, than real market players. Only view devices on the

on the higher price segment have been available. No standard for communication

to these devices has emerged yet, leading to proprietary protocols that allow only

operation between devices of the same manufacturer.

With emerging smart homes connectivity with and among these devices becomes in-

creasingly interesting again. Not only, they can help reducing the electricity bill and

increase overall electrical efficiency, they can also be integrated into comfort or secu-

rity related scenarios.

Figure 2.1.: Home automation devices

16

2.1. Roles

Consumer Electronics: This category of devices comprises those devices that are al-

ready present in many households. TV screens, DVD player, phones, or hifi-systems

are the most important examples of this category.

Some of these devices offer already connectivity. The DLNA standard allows media

sharing and streaming between these devices, independent of the manufacturer. Even

though these solutions sometimes seem to be smart and convincing they have one big

drawback: their services are available only within the category of consumer electron-

ics. These limit the usage of these services to one branch of devices.

In smart homes it should also be possible to create services in all branches. The TV

could not only be used to control entertainment functions, but can also act as an infor-

mation or control device for white goods.

Other devices: Apart from afore mentioned devices other technical equipment is

present in our homes. Mostly these are is legacy systems like lights, light switches,

heating regulators, or blinds that have been present in our homes for a long time.

Smart home services will increase the usability of these devices significantly. Their

operation can be controlled, automated and optimized.

In smart homes an additional category of devices will be added to the existing infras-

tructure:

Home automation devices: These devices will work in the background to enable some

of the operational possibilities of smart homes. Switching actors, binary and other

input devices, heating actors, and dimming actors belong to this category. They offer

functions for switching lights, adjusting the heating or collecting input from a variety

of sensors. In a regular home, these devices (or the functions of these devices) might

be present partly, but the main difference compared to legacy solutions is their offering

of connectivity as a standard.

To sum up, we can say that our current home infrastructure is characterized by a wide

17

2. Smart Homes

heterogeneity of different devices from different manufacturers with widely varying

functionalities. Thus, development of device-independent services that combine func-

tionalities of more than one device is a challenging task. In addition the layout of a

home environment and the available devices is always different.

2.1.3. Services

Services are the enabler for intelligent behavior in smart home environments. They

establish a connection between the user and her environment. One major difference

between current services for homes and smart home services is their ubiquitous avail-

ability and their spanning across multiple devices. While traditional services are usu-

ally bound to a single device, the interconnection of devices in a smart home allows

offering new services that combine devices of different manufacturers and branches.

This combination will deliver new services that increase the benefit for the user in dif-

ferent application areas, ranging from intelligent energy management to control and

safety or services that support daily life and routines for seniors.

2.2. Market analysis

Current home environments are increasingly getting equipped with technical devices.

In 2008 94% of all German households had a TV screen, 70% also a DVD-player. Mo-

bile phones were present in 86%, computers and laptops in 75% of all households1. It

is not unexpected that equipping of households with technical devices will increase

even more in the future, as people tend to adapt to new technologies and devices very

fast.

1Source: German Federal Statistical Office (Statistisches Bundesamt), “Einkommens- und Ver-brauchsstichprobe 2008”

18

2.2. Market analysis

The increasing computing power of devices, and short life cycles of electronic devices

lead to devices that deliver more features than the user actually uses. Either the user

is not aware of the possibilities that the device offers or the operation is too complex

for her. Thus many capabilities of devices will go unused. Another important aspect

for users when adapting to new technology is their wish of staying in control. The re-

quirement analysis within the SerCHo project (see section 6.2) has shown, that control

can appear on different levels:

• Control over usage: Customers want to decide autonomously if they use a par-

ticular device, application or service at all.

• Control over operation: Customers want to control consciously in which way

they use a particular device, application or service.

• Control over time: Customers want to decide actively how much time they are

spending on the use of a particular device, application or service.

• Control over combination: Customers want to decide autonomously which de-

vices, applications or services are part of their smart home solutions.

• Control over evolution: Customers want to decide autonomously if and in which

way they will upgrade their smart home solutions

Smart home solutions will of course take some of the controlling over from the user

to the system or service. In order to give the user not the feeling of losing control,

smart home systems should always provide sufficient information to the user about

the current action. If a user understands why the system has set a device to a spe-

cific operation and if the user has the possibility to overwrite this decision, he will

certainly tend to accept the loose of control better. In addition the benefit for the user

should always be highlighted. Thereby the user can evaluate the benefit over the loss

of control.

End users normally choose the device they want to use depending on the intended

19

2. Smart Homes

purpose and the actual application. Smart home solution will offer systems that are

composed out of a combination of different devices. Hence for end users not conver-

gence on the level of devices but convergence on the level of controlling devices and

accessing content is important.

Current consumer electronics for homes already show some of the requirements that

a smart home solution has to fulfill in order for customers to accept the solution.

Consumer electronics offer their services with no significant boot up time (“instant

on”), have an attractive design that fits in a well-designed living room, try to be user

friendly, and offer plug-and-play characteristics. Smart home solutions will have to

build up on these basic requirements.

For customers the main benefit of smart home solutions consists in the ability to use

personal information and services independent of time, location or device according

to their individual preferences. Customers do not (want to) care about the technology,

which is necessary to realize these benefits. Overall, they want to achieve an improve-

ment of their life by means of smart home solutions, which allow customers to do new

things or to do things in a quicker, better, saver, cheaper, or easier way than before.

Beside the benefits of smart home solutions customers also perceive several threats.

Firstly, they fear an ongoing and cumulative loss of sovereignty and control. More-

over, they anticipate an increasing dependency on technological systems and a poten-

tial intrusion into privacy. Finally, customers assess as a critical aspect of smart home

the risk of unplanned and unsolicited side-effects, e.g. health hazards, environmental

hazards, technical malfunction, additional costs, or extra time.

Overall, customers are at present open-minded towards smart home scenarios and

they show an incipient interest in respective applications and services. Despite the

perceived threats, most customers generally don’t assume an adverse attitude. But

they demand for a comprehensible and stepwise implementation of smart home solu-

20

2.2. Market analysis

tions in order to explicitly address their misgivings and to avoid a mental overload by

complex systems.

The adoption of smart home solutions is influenced by several factors. The demand

analysis within the SerCHo project (see section 6.2) has authored six relevant spheres

of influence:

• Price: level and transparency of end-user prices with respect to the first-time

purchase and the day-to-day usage.

• Value added: concreteness, availability and relevance of the primary features of

an smart home solution.

• Security: data protection, privacy protection and fraud prevention.

• Durability: compatibility, standardization, modularity, extensibility, quality and

persistence of the complete system and its components.

• Simplicity: ease of installation, ease of use and ease of experience.

• Outer appearance: visual integration into the home environment with regard to

aesthetics and design.

Beside these user-driven restraints there are some market-driven influences, which

still hinder the adoption of smart home solutions. Particularly, the comparatively low

broadband penetration in Germany and the not sufficiently solved and standardized

technologies belong to these factors.

Customers who are interested in buying or using smart home solutions can be divided

into the three groups “demanding for simplification”, “demanding for variety” and

“demanding for options”. Each type is characterized by specific motivations, which

represent different success factors for suppliers. Smart home solutions addressing

the type “demanding for simplification” should be comprehensible and straightfor-

ward. Moreover, these customers expect a tangible simplification of their everyday

21

2. Smart Homes

life. The respective smart home solutions should be based upon familiar and estab-

lished components. Customers of the type “demanding for variety” particularly ap-

preciate high grade and innovative smart home solutions. At the same time image

and brand awareness are highly valuated by these customers. The value proposition

should primarily focus on quality and interoperability. Modularity and ability for in-

tegration are the key success factors of smart home solutions of the type “demanding

for options”. Moreover suppliers should emphasize the innovative character of smart

home solutions and the diversity of usage.

If customers perceive a relevant and real, not only fictitious or optional advantage

of smart home services, they clearly show a willingness to pay. The majority of cus-

tomers expect a structural distinction between the application level and the equip-

ment level within pricing models. With services and / or contents they usually prefer

a renting model. Thereby, the payment may consist of a monthly fixed amount, a

use-dependent amount or a combination of both elements. In contrast, with regard

to hardware equipment a purchase model with a unique payment is clearly preferred.

For a single customer the actual willingness to pay strongly depends on his individual

perception of benefits, the relevant application field, and his fundamental expenditure

behavior.

With respect to the choice of a supplier of smart home solutions consumers tend to

differentiate between the initial purchase and the extension of solutions. In the case

of an initial purchase consumers often demand for solutions from one source. This

desire does not necessarily imply that customers expect fully integrated companies

who are providing all components of smart home solutions themselves. They rather

want to have a unique relationship to one supplier in the sense of "one stop shop-

ping" and "one face to the customer". This supplier may even consist of a consortium

of different companies that features a unique customer interface. Additionally, such

a combination must create the impression that the consortium as a whole is work-

22

2.2. Market analysis

ing closely together without friction losses. In case of the extension of smart home

solutions, customers are seeking the adequate supplier in a more open way. Mostly,

they are not committed to suppliers, which they already used in the past. Depending

on their specific needs they also take other providers into consideration. Therefore,

modularity and openness are important features of smart home solutions.

Figure 2.2.: Use cases for smart homes (translated from Strese et al. (2010))

A variety of use cases can be described for smart home services as seen in figure 2.2.

These use cases a motivated by customer needs like entertainment, housekeeping,

or home security. In order to realize these use cases, sensors and actors are needed

to support the implementation of these use cases. Sensors and actors play a central

role in smart home environments; they are the mediator between the user and her

environment. Sensors provide the services with information about the environment

23

2. Smart Homes

and the user, while actors deliver the feedback to the user or change environmental

conditions. If sensing and acting technology gets combined with existing devices, a

new category of devices is being created. These “smart” devices combine well know

devices with additional, intelligent and autonomous functionality. The core of the

smart home environment constitutes out of home networking technologies.

2.2.1. Summary

Until now the development of smart home solutions did not “take off” quite as rapidly

as expected. The main driving forces in the current development and deployment of

home automation have to be identified. Saving energy, increasing of comfort and

simplification of the running of the home could be it. In addition the need for health

and social services for specific target groups could also support turning our homes

into smart homes.

In the following subchapter we’ll describe the relevant application areas in detail.

2.3. Application areas

Smart homes are especially characterized applications that offer their services to the

occupants. Services for smart homes make use of the technology and offer services

that adapt to the environment and to the user’s situation. Services tend to evolve

from individual services for specific problems to more complete solutions that ad-

dress a combination of different application areas, in order to support the occupants

in a more complete way. Building up smart home solutions requires composing ser-

vices and usage scenarios, which fit well together in terms of their basic character.

This combination of devices and services can result in value-added services that en-

courages customers to invest in smart home solutions.

24

2.3. Application areas

Figure 2.3.: Preferences of end users for smart homes (Szuppa, 2007)

Customer surveys as shown in figure 2.3 show, that not one single killer application

for all consumers exists, but one can identify main applications areas for smart home

solutions. In the following we will highlight the five most common applications areas.

2.3.1. Comfort

Services that increase the comfort of the occupants are the main driver at customer

side. These services help them to reduce burden of annoying tasks or make occupants

feel more comfortable in their homes. Services in this category generally increase the

service level of the home.

Comfort related services adjust lighting and temperature to make living in the house

a more pleasant experience. In the morning, the inhabitant could awake to a home

already at its ideal temperature as the heating or air conditioning has already adjusted

itself on at a preset time. On the way to the bathroom movement sensors control

25

2. Smart Homes

lighting, and ensure instant availability of hot water by turning in the hot water pump.

Using a touch screen on the way to the kitchen starts a breakfast scene. Lightning in

the kitchen is turned on, the favorite morning news station is switched on the TV, and

the coffee machine serves a fresh latte. An intelligent fridge updates the shopping list,

suggests a meal plan for the week based on user preferences and diet, and delivers

health information for each dish. Before leaving the house for work, the occupant is

notified about open windows or doors. In the afternoon, automated blinds prevent

the sun to heat up the living room to ensure, a comfortable temperature when the

occupants returns from work. In the evening, the lighting is set automatically for a

family meal, dinner party, or a television evening, with simultaneous operation of

suitable devices.

2.3.2. Communication and Entertainment

Closely related to comfort is the area of communication and entertainment services.

Entertainment services in a smart home control the consumption of audio and video

media. Home theater systems, audio and visual equipment can be used to recreate a

cinema experience at home. The system automatically adjusts lighting levels, closes

blinds and powers up audio visual equipment to suit the entertainment experience.

As the inhabitant sits down to watch a DVD or television program, the TV screen can

be automatically raised, or a projector screen lowered. Audiovisual content can be

accessed and played on any output device within the smart home. Multi-room audio

systems automatically pipe music from the hifi-stereo-system to any room while the

inhabitant moves through the rooms during his daily activities. Automated recording

of favorite shows, or program recommendation based on learned user preferences

based on previous watched program will enhance our entertainment experience even

further.

26

2.3. Application areas

2.3.3. Safety and Security

Another prominent area for services in smart homes is safety. Everybody wants to

feel safe at home and protect her possessions. Therefore any technology that supports

these wishes will be gladly accepted by occupants of homes. Alarm systems are a

familiar product to many of us. Traditionally, an alarm system protects a home while

the inhabitants are away. It uses glass breakage detectors or motion sensors after it has

been armed to set up an alarm. Alarm systems in smart homes can provide even more

features; they can monitor regular behavior and create an alarm or a warning when

something unusual occurs. It can also turn off the lightning and the stove, or close the

blinds when a thunder storm approaches. Remote access to the system allow the user

to check from a distance if everything is alright – offering them a feeling of safety.

2.3.4. Energy Management

Energy efficiency is becoming a more and more important topic in our society. Pre-

serving energy can start within our own homes. Think of the following scenario: In

order to save on heating and thus to protect our environment the temperature is low-

ered in the absence of the occupier, or when windows are opened. Shortly before the

arrival of the inhabitant, the temperature will be set to a comfortable level again, e.g.

via a cell phone or automatic synchronizing with the user’s calendar. In general, heat-

ing, ventilation and blinds co-ordinate with each other and create an energy-efficient,

pleasant climate.

For occupants it is not only possible to save energy but also costs. Under pressure from

government regulations, energy suppliers start to roll out electricity smart meters.

Smart meters allow accurate real-time information on energy use in the home to the

consumer and back to the energy supplier. Based on smart meters it is possible to

offer tariffs that charge rates based on the time of the day that usage occurs, so called

27

2. Smart Homes

Time of Use (TOU) tariffs. Usually this means a lower rate during the night when

there is less demand for electricity and higher rates during the day when there is more

demand for electricity. In order to do better with TOU tariffs, it is necessary to shift

usage of appliances to lower priced zones.

Too complex tariff structures would overwhelm end-consumers making it impossible

to them to get the most out of the new possibilities. Thus, smart homes will not only

offer alternative means of displaying energy consumption than we are used today– i.e.

through mobiles, the internet or via digital TV, but also allow intelligent management

of appliances, based on forecasted energy prices and user preferences resulting in a

cost and user optimized usage of appliances.

For energy suppliers a tariff based management of energy demand can also be ad-

vantageous. Tariff-based incentives for shifting the usage of appliances to other times

can be used to flatten the load curve. A flattened load curve results in a better over-

all efficiency generation of energy. Proposals of integrating electrical vehicles into the

home energy management go even further. The idea behind that is that the energy

stored in batteries could be used during peak time in order to reduce the current en-

ergy consumption of a smart home during peak times and to recharge the batteries

off-peak.

2.3.5. Ambient Assisted Living

Another application area that does not come into the mind of customers at first is Am-

bient Assisted Living (AAL). AAL is about concepts, products and services that com-

bine new technologies with social environment with the aim to increase the quality of

life for people in all stages of life. AAL is motivated by the unstoppable demographic

change. In 2035 Germany will have one of the oldest populations in the world. More

than half of people will be 50 years and older; every third person will be older than 60

28

2.3. Application areas

years. This is a challenge for society, economy and politics to develop and implement

affordable solutions that increase the quality of life while keep in check costs for social

systems.

Figure 2.4.: AAL innovation model

Smart homes can help elderly people to improve their everyday life, increase their

security, and help keeping them social contacts. Smart homes can enable them to

perform activities by themselves they were not able to do before and which are im-

portant for their daily life. Improving the quality of life of elderly people for as long

as possible will also allow them to live longer in their familiar surroundings and will

help the healthcare system to reduce costs for nursing fees. As most elderly suffer

from personal health, maintaining health and functional capability of the elderly and

promoting a better and healthier lifestyle for possible health risks is an additional re-

quirement for AAL.

On the other hand older people are not very familiar with technical solutions; they

might feel to be overstrained by the technology. Therefore it is particularly important

for smart home for the elderly to make services and solutions not to complicated.

29

2. Smart Homes

2.3.6. Summary

We have shown that smart homes can improve the quality of living in different ap-

plication areas. Considerable advantages need to be present for the user to give him

motivation to invest into new technologies needed for realizing smart homes. These

technologies already exist, thus in the following subchapter we’ll take a look at tech-

nologies available for realizing smart home solutions.

2.4. Technologies

Different kinds of technologies form the basis for realizing smart home solutions. They

can be divided into three main groups of devices: Sensors, actors and communication

technologies, actors that control home appliances, input and output devices that allow

for the control and operation of services installed in the home, and a communications

network that connects all the devices and lets them exchange information. Often the

boundaries between these components are fluent. Some home automation devices are

sensors and actors simultaneously. They allow on- and off switching of load while

also sensing the current energy consumption.

Sensors and other measuring devices collect and distribute a variety of information

of the environment they are installed in. They perceive current status information as

well as and changes of measured valued. A few examples are information about tem-

perature, light, movement, smoke, noise, resource consumption and so on. Sensors

information delivers the basis for smart home services to create better, traceable, yet

smarter decisions.

Actors play the role of the extended arm of the inhabitant. They can be found in many

home appliances. They turn on lights, open and close blinds, turn of the oven, adjust

the radiator or air conditioning system, and open and close doors and windows, and

30

2.4. Technologies

so on. Actors replace the direct user interaction with devices and appliances in smart

home; they are the enabler for home automation.

Special characteristics of smart homes are the interplay of different technologies. A

communication network forms the basis for connection of devices and sensors within

a smart home. These communication networks exist in manifold ways.

2.4.1. Home Automation systems

Several competing home automation systems are available to support the realization

of a smart home. These technologies have been created directly for the intended use

in smart home environments. They offer sensing and acting devices, as well as a com-

munication network interconnecting these devices. In the following we will present

the most widely used home automation systems.

KNX

KNX is field bus system for home and building automation. KNX uses a standard-

ized OSI-based network communications protocol2. The intended use of this protocol

makes KNX independent of any particular hardware platform. KNX is a further devel-

opment of the European standards EIB, BatiBus and EHS. While keeping the interop-

erability with EIB, KNX added the configuration mechanisms and transmission media

of BatiBus and EHS to the standard. The KNX Association with more than 110 mem-

bers certifies products that implement the KNX standard. Certification guarantees

interoperability between products. The KNX standard support different transmission

media for operation:

• Twisted pair with 9,6 kbit/s with a max distance of 1000 meter

2http://www.knx.org/knx-standard/standardisation/, accessed on December 10, 2010

31

2. Smart Homes

• Powerline communication (PLC) with data rates of 1,2 kbit/ s with a max. dis-

tance of 600 meter

• Radio frequency (RF) at 868 Mhz

• Ethernet cable with 10 Mbit/s

The most commonly used communication technology today which is supported by

almost every KNX appliances manufacturer is the twisted pair system - even though

it has the disadvantage of a separate cable that has to be installed. PLC and RF have

less support by the manufacturers, even if they are more easily to install. KNX over

Ethernet cable has the smallest dissemination among used technologies.

Figure 2.5.: KNX devices for home automation

KNX has a broad support from manufactures in Europe. Figure 2.5 gives an overview

about available devices, sensors and actors that support the KNX standard. KNX

offers devices and solutions for almost every possible use case for smart homes. How-

ever, constantly high prices for the components and the difficulty of retrofitting pre-

vent a wider spread of the technology until now.

32

2.4. Technologies

X10 and INSTEON

X10 3 is one of the oldest communication standards that enable communication among

electronic devices for a home environment. In most application areas X10 uses house-

hold electrical wiring’s for communication between devices, even though a radio fre-

quency X10 protocol has also been defined. The usage of the wires in a house allows

realizing automation and controlling of devices without the need of rewiring. Adapter

plugged into regular power outlets can communicate to or receive signals from other

devices using the same technology. Basic functions are turning devices on and off and

reporting of status information. More advanced devices like cameras, or sensors are

also available.

The standard X10 power line and RF protocols also lack support for encryption, and

can only address 256 devices. As with all power line technologies, signal filtering is

needed, so that close neighbors using X10 may not interfere with each other. Interfer-

ing RF wireless signals may similarly be received, with it being easy for anyone nearby

with an X10 RF remote to wittingly or unwittingly cause mayhem if an RF to power

line device is being used on a premises. Despite some drawbacks of this technology,

it has become quite popular in the United States. One reason for that might be the

inexpensive availability of new components.

Two main reasons prevent a broader distribution of X10 technology in Germany. Firstly,

technical regulations for wireless communication limit the transmission power to 5mW

per device. With this small power it was nearly impossible to guarantee a failure-free

operation. Secondly, the usage of three phase network required the installation of a

phase connector, which made the usage of X10 in private homes uneconomic.

INSTEON 4 has been developed to address the inherent limitations in the X10 standard

a new standard while keeping compatibility with X10. Backward compatibility with3http://en.wikipedia.org/wiki/X10_(industry_standard), accessed on October 15, 20104http://www.insteon.net/pdf/insteondetails.pdf, accessed on November 23, 2010

33

2. Smart Homes

X10 allows home owners to migrate to the new INSTEON technology without having

to throw away all their used X10 devices.

LonWorks

LonWorks was created to address the needs of control applications. Echelon Corpo-

ration is the driving force behind this technology. The LonWorks networking technol-

ogy is aproved as an international ISO/IEC standard 5. It is currently mostly used in

business environments, less for home automation purposes. Machine control, street

lightning, air conditioning systems, or intelligent electricity metering are typical cases

of application. For example, Italian energy supplier ENEL uses LonWorks as the basis

for its advanced metering project with more than 20 million nodes in operation.

Using a peer-to-peer protocol LonWorks can use twisted pair, power-line, fiber optics,

and RF as transmission media. The twisted pair layer can transfer up to 78 kbit/s of

data, while the power line achieves either 5.4 or 3.6 kbit/s, depending on the used

frequency.

BacNet

BacNet is a data communication protocol for building automation and control net-

works that has been standardized under ISO 16484-5 6. It has been developed by the

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

Interoperability between devices from different manufacturers is ensure by BACnet,

if all the project partners involved agree on certain BACnet Interoperability Building

Block (BIBB) defined by the standard. A BIBB defines the services and procedures that

need to be supported at server and client side to achieve a specific requirement of the

5http://www.lonmark.org/news_events/press/2008/1208_iso_standard, accessed on August 8, 20106http://www.bacnetinternational.org/displaycommon.cfm?an=1&subarticlenbr=23, accessed on

March 7, 2011

34

2.4. Technologies

system. For each device a PICS (Protocol Implementation Conformance Statement)

lists all supported BIBBs, object types, character sets and communication options.

digitalSTROM

A relatively new technology in home automation is digitalSTROM7 developed by ETH

Zürich. It offers a simple method of connecting electrical appliances in a home. The

system works over the existing mains making it an optimal solution for upgrading

existing homes to smart homes. A small server installed in the fuse box acts a central

controlling unit.

Ant-size chips (see 2.6), mounted directly into the devices or in an adapter plug, it lets

devices communicate with one another. Each device equipped with a digitalSTROM

chip can be addressed with its unique address. In contrast to other power line based

technologies, digitalSTROM offers an interception-proof power line communication

system. It only communicates within a single circuit within a private dwelling. Out-

side of this circuit, including parallel running wires, it is physically invisible. Another

unique feature is two methods of measuring power consumption of electrical devices.

A per zone power consumption of its electric circuits in combination with calibrated

value of the house meter as a reference and a per device refined measurement down

to the individual device using a digitalSTROM dSID chip.

7http://www.digitalstrom.org, accessed on April 7, 2011

35

2. Smart Homes

Figure 2.6.: digitalSTROM chips - © aizo ag

Controlling of the system can be done either with novel digitalSTROM switches, which

are equipped with a LED. The LED indicated the application area that is currently

being controlled with the switch. Complex configurations can be set-up with a web-

based configuration utility. The server installed in the fuse box offers also an inte-

grated web server allowing external services to access and control digitalSTROM de-

vices.

Several target application areas including comfort, security, entertainment, and energy

allow a broad support for developing new applications for a smart home.

EnOcean

EnOcean offers self powered devices that use energy harvesting mechanisms for Home

automation. EnOcean technology is making use of energy created from slight changes

in motion, pressure, light, temperature or vibration allowing to build building battery-

less and wire-free control sensors. Thereby sensors can be easily installed and won’t

need any maintenance. Using wireless transmission media at 868 or 315 Mhz, energy

efficiency during radio reception and transmission is also of key importance.

36

2.4. Technologies

Figure 2.7.: EnOcean power generator transmitter module - © www.enocean.com

The EnOcean Alliance drives the standardization of communication profiles to ensure

communication between sensors and gateways of different manufacturer. The EnO-

cean Equipment Profile (EEP) is a unique identifier that describes the functionality of

an EnOcean device irrespective of its vendor. Different interfaces to other technologies

like LonWorks, EIB/KNX and TCP/IP allow integration into and extension of already

established home automation solutions.

2.4.2. Communication Technology

Typically different networking technologies exist in a smart home, as there has no

standard technology emerged yet. The communication network lets different devices

within a smart home exchange data.

Communication networks can be divided into two main categories: wired and wire-

less technology. While the former has advantages regarding security concerns, it lacks

ease of installation. The installation of the latter is in most cases more easily, yet it

has some other drawbacks. Besides concerns of inhabitants regarding their well-being

because of the wireless installation, the power supply of wireless sensors is often a

37

2. Smart Homes

problem that can easily sour installation.

Wireless Technologies

Wireless Sensor Networks have become increasingly popular as connectivity networks

for smart environments (Pensas and Vanhala, 2010). Wireless Sensor Networks for

smart homes allow a flexible and comfortable integration of sensors and devices into

the home environments. Installation can be easily done, as only power supply needs

to be provided. With batteries getting more powerful, in many cases one can even

abandon direct power supply and integrate a warning system that alarms the user

just before the device gets unusable. Recently, new approaches like the EnOcean tech-

nology 2.4.1 allow realization of battery-less, wireless control systems only based on

the use of energy created from slight changes in motion or pressure.

Bluetooth Bluetooth is a standardized and royalty-free radio technology for wireless

voice and data communication of up to 256 participants, with only 8 mostly small

mobile devices, such as phones with a wireless headset, laptops with a printer can be

active simultaneously via a short distance up to 100 meters.

Since version 2.0, data rates of around 2.1 Mbit/s can be transferred and thus new

application areas of Bluetooth technology are possible, like the encrypted transmission

of audiovisual information. The available bandwidth in the 2.4 GHz band is shared

between all participating devices. Disorders may be caused, however, e.g. by garage

door openers, microwave ovens and cordless phones which use the same frequency

band.

Currently Bluetooth is very common for the interconnection of mobile phone and con-

nection of mobile phones to other devices. In home automation Bluetooth has not

gained a reasonable market share yet.

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2.4. Technologies

DECT DECT (Digital Enhanced Cordless Telecommunications) is a European Stan-

dard for digital wireless phones. DECT has coverage of about 30 to 50m within build-

ings using 120 encrypted channels at using the frequency band between 1880 and 1900

MHz. In addition, DECT-based wireless data networks with data devices on can be

operated. The DECT Application Profiles contain additional specifications defining

how the DECT air interface should be used in specific applications to achieve max-

imum interoperability between DECT equipment from different manufacturers. The

Packet Radio Service DPRS and the Multimedia Access Profile e.g. DMAP permit data

with higher data rates of up to 2 Mbit/s.

Until now DECT the majority of DECT product shipments are in the residential appli-

cations with single base station and single handset configurations for wireless phones.

GSM/UMTS GSM (Global System for Mobile Communication) is currently the defacto

standard for mobile phones in Europe. The radio is based on cells, whose expansion

depends on the number of participants. GSM is used for voice telephony and Short

Message Services SMS at data rated of 9.6 kbit/s. Smart phones, notebooks and PDAs

preference data over the wireless network with the more recent GPRS (General Packet

Radio Service) with a maximum data rate of up to 160 kbit / s or EDGE (Enhanced

Data Rates for GSM Evolution) with a realistic data rate of 110 kbit / s for full mobility

and 220 kbit / s in stationary operation.

UMTS (Universal Mobile Telecommunications System) is the follow up standard for

mobile communications. While GSM is called second generation (2G), UMTS is re-

ferred to third generation (3G). UMTS was mainly developed to increase the available

data rates. It enables data rated up to 2 Mbit/s. Based on the UMTS standard HS-

DPA (High Speed Downlink Packet Access) enables even higher data rates up to 7,2

Mbit/s.

While the general availability of GSM/UMTS speaks for this technology, the related

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2. Smart Homes

costs hinder a broader usage for smart home devices. One exception are smart meter,

where many energy provider use GSM for transmission of usage and billing informa-

tion.

Konnex-RF Konnex-RF (KNX-RF) is a wireless extension to the twisted pair based

Konnex Home Automation bus. For installation conditions, where neither twisted

pair nor power-line communication can be used, KNX-RF allows to transfer data wire-

lessly, while still being able to cooperate with wired KNX devices. As the complete

KNX standard also the wireless part KNX-RF is vendor independent. Using the 868

MHz Konnex-RF shows a better transmission behavior within buildings compared to

the 2.4 GHz band used by Wi-Fi and many other protocols.

RFID RFID (radio frequency identification) is suitable for wireless identification of

goods (such as serial numbers or product name) and even over a distance of a few

millimeters up to several meters. Currently RFID is increasingly used for inventory

management, but is also interesting for refrigerators, microwave ovens, etc. where the

RFID labels on foods automatically recognize the date of expiry and provide possible

preparation tips.

Wireless-USB Wireless USB is a high-speed wireless networking technology for var-

ious devices, such as keyboards, mouse, camera, printer and so on. It provides a com-

plement to the traditional USB interface. Ultra Wideband (UWB) used as the radio-

technical base, works with transfer rates of 480 Mbit/s at distances of 3 meters.

WLAN WLAN (Wireless Local Area Network)refers to a wireless network, which be-

long to the network devices in a radius of several meters to several kilometers at a

speed of 11Mbit/s with 802.11b and 54Mbit/s for 802.11g and linking example with

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2.4. Technologies

wireless internet supplies. While the IEEE 802.11n working group, currently finished

the draft for the standardization of high-speed WLANs with 300 Mbit/s, already a

discussion about a gigabit wireless network has started.

WIMAX WIMAX (Worldwide Interoperability for Microwave Access) is a wireless

technology for wideband, bidirectional high-speed transmissions in the access net-

work with about 75 Mbps at a range of up to 50 kilometers. Unfortunately WiMAX can

not fulfill both goals at the same time. It can either operate at higher bitrates or over

longer distances but not both: operating at the maximum range of 50 km increases

bit error rate and thus results in a much lower bitrate. WiMAX refers to interoperable

implementations of the IEEE 802.16 wireless-networks standard. WIMAX is seen as

a technology that provides next-generation of wireless technology designed to enable

pervasive, high-speed mobile Internet access to the widest array of devices including

notebook PCs, handsets, smartphones, and consumer electronics such as gaming de-

vices, cameras, camcorders, music players, and more. WiMAX is a long range system,

covering many kilometers, which uses licensed or unlicensed spectrum to deliver a

point-to-point connection to the Internet.

Like most wireless systems, available bandwidth is shared between users in a given

radio sector, so performance could deteriorate in the case of many active users in a

single sector. In practice, most users will have a range of 2-3 Mbit/s services and

additional radio cards will be added to the base station to increase the number of

users that may be served as required.

ZigBee ZigBee is an industry standard based on IEEE 802.15.4 for wireless sensor

and control networks with a low data rate of 20 kbit/s or 250 kbit/s to short distances

to about 75 meters. It is intended for the use of maintenance-free wireless switches

and wireless sensors with limited energy supply (e.g. battery) in poorly accessible

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2. Smart Homes

areas, where the replacement of batteries is only possible with great effort. To achieve

this, ZigBee offers a comparatively low data rate. Main focus is the lowest possible

power consumption, so battery-powered devices can be operated for several months

to several years without replacement.

The ZigBee, and IEEE-802.15.4-standard offer the developer three different types Zig-

Bee devices. With these devices, a ZigBee Personal Area Network (PAN) is built. There

are three roles that a ZigBee device can take:

• ZigBee End Device: Simple devices such as light switches implement only a part

of the ZigBee protocol, and therefore are also called Reduced Function Devices

(RFD). They log on to a router of, thus forming a network in star topology.

• ZigBee Router: Full function devices (FFD) can also act as a router, log on to an

existing router and create a tree network topology.

• ZigBee coordinator: Exactly one router in a PAN will also assume the role of the

coordinator. He sets the basic parameters of the PAN and manages the network.

Since the ZigBee standard uses one coordinator, when using indirect addressing, a

failure of the coordinator will jeopardize the entire network, since all of these devices,

and routing information are kept in a volatile memory. A ZigBee network is hierar-

chically structured and has an single point of failure (SPoF). However, routers can be

configured so that they take over the task of the coordinator in a case of failure.

An advantage of ZigBee technology is it’s wireless multihop ability. Long distances

can be bridged, as devices can forward information of adjacent devices.

Z-Wave Z-Wave was developed by Danish company Zensys and the Z-Wave Al-

liance for home automation with special focus requirements of home automation tech-

nologies. It operates at 868 Mhz allowing data transmission rates between 9.600 bit/s

and 40 Kbit/s.

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2.4. Technologies

Z-Wave uses a meshed network topology, that is, each network node is connected

to one or more other network nodes. This has the advantage that a message can be

transmitted between two network nodes, even if they cannot communicate directly

with each other as they are too far apart. In this case, the message is transmitted

over one or more intermediate nodes. Due to its similar features Z-Wave is in direct

competition with ZigBee.

2.4.3. Location

Location information is important in almost every smart home scenario. Using explicit

input methods are one easy way to provide context-aware systems with location infor-

mation. Users need to inform the system about changes of their location. This could

be done e.g. by using a finger print sensor before entering a room or letting the user

enter his current position in a field before starting service usage. This explicit user

interaction for acquiring context information is contradictory to the vision of ubiq-

uitous computing. Also the provided information may not be very accurate neither

can it be dependably, without demanding too much effort from the user. To realize

autonomous smart home systems, only automatic location sensing techniques can be

used and will be considered in the following. Depending on the needed precision of

the information it is more or less difficult to obtain location information.

Technologies

Common to all location sensing technologies is the use of radar to define the position

of the client. In the following we present the main technologies that can be used to

determine the location of an entity.

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2. Smart Homes

Nearest sensor The least precise but simplest method is the nearest sensor method.

This capability determines the access point or cellular base station to which a client

device is associated. It assumes that this sensor is the closest sensor to the device. It

then computes how far the signal radiates. The diameter of the 360-degree radiation

"cell" surrounding the sensor is as precise as this method alone gets, even presum-

ing that the client does indeed associate with the nearest sensor. If a base station

has approximately a 100-by-100-meter coverage area, for example, the nearest-sensor

method tracks the client to within a 10,000-square-meter area. Note, though, that a

client might associate with a sensor a bit farther away if the nearest one is overloaded

or its signal strength is otherwise not as strong.

Triangulation The usage of triangulation methods goes back to ancient times. Trian-

gulation measures angles between three or more nearby known points. The intersec-

tion of those angels is calculated as the client location. With triangulation, accuracy

is reduced if the signal is reflected off of the walls in a room or if the signal has taken

multiple paths before reaching the device. Triangulation does not take into account

the effects that a building and/or other objects can have on a signal. Trilateration is

similar, but uses the distance between known points, rather than the angles between

them.

Wi-Fi Positioning Normally indoor location sensing systems require installing ad-

ditional hardware infrastructure. As in today’s cities more and more wireless access

points are being installed, one started to use those access points for location sensing.

A requirement for using this technology is a map of well-known positions of access

points. Today companies have started to drive through major cities with specially

equipped sensor vehicles that scan existing Wi-Fi access points and their position. Us-

ing triangulation or nearest sensor technology a Wi-Fi client can determine its location

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2.4. Technologies

very accurately. Apple’s first generation iPhone mobile device was one of the first

broader available devices that made use of Wi-Fi positioning (due to the lack of an

internal GPS sensor). Surprising to many, the device showed a great accuracy within

major cities, but as expected, had no luck in getting a position in rural areas.

Microsoft Research has developed RADAR, a building-wide tracking system based on

the IEEE 802.11 Wi Fi technology (Bahl and Padmanabhan, 2000). RADAR measures,

at the base station, the signal strength and signal-to-noise ratio of signals that wireless

devices send, then it uses this data to compute the 2D position within a building.

Microsoft has developed two RADAR implementations: one using scene analysis and

the oth