Special Feature

Home Network Service Management
Technologies
Masanori Ogawara†, Eiji Kobayashi, and Ikuo Yoda
Abstract
The next generation of home networks will offer flexible service configurations by linking multipledevices on a home network. This article introduces the architecture of Home Service Harmony, a platform for next-generation home network services. It achieves user-oriented service control by fully managing multiple services and devices.

1. Next-generation home network services
The widespread use of optical fiber and ADSL
(asymmetric digital subscriber line) is encouraging
the use of home networks. Conventional home networks are local area networks (LANs) that connect
broadband routers to the user’s personal computers(PCs). These days, however, various home appliances(audio/visual (AV) equipment, white goods, etc.) can
also be connected to them. Typical services available
on current home networks include remotely controlling digital home appliances (e.g., turning an air conditioner on and off) and monitoring the surroundings(home security). In addition to these services, many
new services are expected to become widely available
via home networks.
NTT Cyber Solutions Laboratories has been studying these next-generation home network services tocreate higher value-added services by combining
appliance functions as shown in Fig. 1. Conventional
services are provided by the appliance features themselves. Since most devices are digital these days, they
can be remotely controlled and their status can bechecked via home networks. Therefore, by combining the functions of multiple devices, we can flexibly
create advanced services that cannot be provided byany single device. For example, a videophone service
can be created without dedicated equipment or PCs,
by combining a user’s existing TV (monitor) with a† NTT Cyber Solutions Laboratories
Yokosuka-shi, 239-0847 Japan
E-mail: ogawara.masanori@lab.ntt.co.jp

Vol. 3 No. 1 Jan. 2005

video camera. A new automated home service can bemade by combining the window blinds, lights, and air
conditioners, etc. The scope of cooperation will
spread beyond localized combinations of homeequipment to services that use the Internet.
This kind of cooperation among appliances
depends on the standardization of home network protocols, such as UPnP (universal plug and play) [1] forAV equipment and ECHONET (energy conservationand homecare network) [2] for white goods. As standardization advances, it will become possible to control and monitor more and more appliances, and it
will become practical to provide services by combining the features of different devices.
2. Service management
Various services are provided in homes, and theircontrol functions vary widely from service to service.
For example, the functions for a TV broadcast service
include “turn off TV” and “turn down the volume”,
while those for telephone service include “transfer”
and “switch to answerphone”. As the varieties of services available via home networks increase, theircontrol functions will increase in number and kind.
In addition, the services are often provided as a set
rather than individually. Sometimes a user consciously requests multiple services at the same time andsometimes he/she unintentionally receives multiple
services as a result of external events. For example, if
a visitor arrives while the user is watching TV, theimages from the door-phone can be displayed on thesame TV monitor. In this case, the user needs to select17Special Feature

Data center
Speakers

TV monitor

Printer

PVRPCHomegateway

Video camera

VideophoneserviceInternetFAX

Telephone

Refrigerator

OfficeWindowblinds

Automatedhomeservice

LightsAir conditioners
PVR: personal video recorderFig. 1. Next generation of home network services.

the service because the TV broadcast and door-phoneservices will both try to use the same TV monitor. If
the TV program is important, the user could display
the door-phone image in a sub-window or record theTV broadcast on a personal video recorder for laterviewing. If the user is not really paying attention tothe program, he/she could let the door-phone image
take over the whole screen.
If these related services could be controlled automatically, their user-friendliness would be increased.
However, the status of the user and service are constantly changing. The traditional service management
system covers fixed services, so it cannot handle collaboration among independent services. Moreover,the service control is uniform because the contexts
that determine the priority are also fixed. Therefore,
uniform control, like always giving priority to thedoor-phone, is not an appropriate solution. We needto provide total management of the services provided
in the home so that we can determine who uses theservice and for what purpose.
3. User-oriented service control
There are two situations where service control
requires the comfortable use of multiple services atthe same time. One is where there are conflicts
18

among the devices, home network bandwidth, power,
and so on. The services should be controlled to avoid
such conflicts. Here, we call resources that can actually be assigned to services (such as devices and network bandwidth) “actual resources”.
The other situation is where the user cannot receive
the services at the same time. For example, if a telephone call arrives while the user is watching TV,
although there is no appliance conflict because theservices use different appliances, the user must usually take some action, such as turning off the TV,turning down the TV volume, or switching to answerphone. This indicates the need for control. We canregard this as a conflict in human reaction capabilities: watching, listening, and speaking, which we call“user functions”. In addition, some combinations ofservices (e.g., cooling and heating services) are illogical. We regard these as conflicts in the home environment. Resources that cannot actually be assigned
to a service, like the “capability to react to service”
and “home environment” are called “abstractresources”, as seen in Table 1. As mentioned above,
when abstract resources conflict, we must control theservice to avoid conflicts, even if there are no conflicts among the actual resources. For example, theTV broadcast service involves user functions such aswatching and listening, and the telephone service
NTT Technical ReviewSpecial Featureservices by comparing the types of abstract resourcesthat they require, allowing us to integrate the different services.

Table 1. Services and abstract resources.
Service

Abstract resources

TV broadcast

Watch and listen

Telephone

Listen and speak

Visual telephone

Watch, listen, and speak

Home security

Secure indoor environment

Automated home

Temperature environment andlighting environment

4. Home Service Harmony

uses the “listen” and “speak” user functions. In thiscase, we control these services to avoid a conflict inthe “listen” user function. How to implement thesolution depends on the status of the service usage.
We could turn down the volume of the TV broadcast
service or pass the incoming call to an answerphone(i.e., not assign the “listen” user function to the telephone service).
By introducing the concept of abstract resources
and avoiding conflicts, we can achieve user-oriented
service control, which cannot be achieved simply byfocusing on conflicts in actual resources. Moreover,
we can check the relationship among independent

We have developed Home Service Harmony: a service control platform for providing the next generation of user-oriented home network services [3]. As
shown in Fig. 2, Home Service Harmony consists offour program module layers. Actual resources, suchas home equipment, network bandwidth, and a person’s schedule and address book, and abstract
resources such as user functions are indicated asresource objects. These resources are centrally managed in the resource management layer. Each modulein the service generation layer constructs services bycombining multiple resources, and these services are
fully managed in the service control layer. The implementation of these program modules complies with
the OSGi Alliance* specifications [4]. OSGi is thestandard for open service platforms for home net* See the footnote on page 14.

Service control layer
Service manager

Service generation layer
Service 1•••Service nResource management layer
Profile manager

Home network
resource manager

Resource layer
Resource 1

Resource 2

Resource 3•••Resource n•••
Schedule andaddress book

Telephone

TV monitor

Network bandwidthFig. 2. Structure of Home Service Harmony program modules.

Vol. 3 No. 1 Jan. 2005

19

Special Feature

Resource
assignment

Decide the scopeof control

Servicemanager

History/preference
information

Environmental
resources: 100%

“Watch”: 100%
“Listen”: 10%“Listen”: 90%“Speak”: 100%

Air conditioners: 100%
Lighting: 100%

Network bandwidth: 0%
Living room TV: 100%

Network bandwidth: 10%
Telephone: 100%

Automatedhomeservice

No user resources, but theenvironmental resources areassigned. Service should becontinued.

Videoservice•••

The “listen” user resourceis 10%, so the user cannot
listen to sound (mute control).

Telephoneservice

The assigned user resources “listen” and“speak” are sufficient to start service, butsince network bandwidth is low, the soundquality should be kept low.

Fig. 3. Service control and autonomous decision of scope of control according to resource assignment.

works, and it enables the dynamic addition/deletion/updating of program modules during system
operations. Therefore, we can dynamically
add/enhance services and resources to achieve a highlevel of maintenance performance/operability.
The service control of Home Service Harmony isachieved through resource assignment by service
management, as shown in Fig. 3. As the home network connects the various devices and sensors, etc.,
we can identify the appliance status, environmental
information, and the user’s location in real time. For
example, we could use RFID (radio frequency identification) readers and tags to identify the user’s location. Based on this information, we can check forconflicts in actual and abstract resources and estimate
the importance of each service by considering theusage history and preference information. For example, the usage history indicates the user’s control pattern, so the service manager can judge the importanceof a service from the frequency of the service control.
The service manager then assigns the resources toservices according to the importance of each service,
so conflicts between those resources can be avoided.
In other words, the service management does notissue commands unique to each service like “replay”
and “stop”. It just allocates the amount of actual and20

abstract resources available to each service. Each service then autonomously decides the specific control
operations, based on the assigned resources. In thecurrent version, the service manager allocates
resources in proportion to the service’s importance.
Thus, the adequacy of the resource allocation
depends on the estimation of the importance.
Because the service manager just coordinates theabstract and actual resource services, its overhead isvery small. In addition, because its control method is
general and independent from the unique control
commands of each service, it can be easily enhanced
to handle new services.
5. Future plans
Home Service Harmony now controls AV appliances using abstract resources, such as user functions, but it cannot handle white goods. Furthermore,
it is difficult to handle controls when several users arereceiving the same service. In future, we will incorporate technologies for learning and recording theuser’s actions and making this information available
to all types of appliances. We will develop a service
generation tool that complies with this method.

NTT Technical Review

Special FeatureReferences
Masanori Ogawara
[1]
[2]
[3]

[4]

http://www.upnp.org/
Echonet: http://www.echonet.gr.jp/english/index.htm
E. Kobayashi, M. Ogawara, and I. Yoda, “Multi Services Coordinate
System over Home Network,” Technical Report of IEICE, Vol. 103,
No. 42, TM2003-115, May 2003.
R. Kawamura and H. Maeomichi, “Standardization Activity of OSGi
(Open Services Gateway Initiative),” NTT Technical Review, Vol. 2,
No. 1, pp. 94-97, 2004.

Research Engineer, Network Appliance andServices Project, NTT Cyber Solutions Laboratories.
He received the B.E. and M.E. degrees in electrical engineering from Keio University, Yokohama, Kanagawa in 1992 and 1994, respectively.
In 1994, he joined NTT Network Service Systems Laboratories, where he was engaged inR&D of WDM-based broadcast-and-selectswitching. His current research interest is useroriented service platforms on home networks. He
received the paper award from the Institute ofElectronics, Information and Communication
Engineers (IEICE) of Japan in 1999. He is amember of IEICE.

Eiji Kobayashi
Research Engineer, Network Appliance andServices Project, NTT Cyber Solutions Laboratories.
He received the B.E. and M.E. degrees in integrated design engineering from Keio University,
Yokohama, Kanagawa in 2000 and 2002, respectively. In 2002, he joined NTT Network Innovation Laboratories. He has mainly been engaged
in R&D of service management systems forhome networks. His research interests are home
network services, context-aware services, andintelligent systems. He is a member of IEICE.

Ikuo Yoda
Senior Manager, Network Appliance and Services Project, NTT Cyber Solutions Laboratories.
He received the B.E. and M.E. degrees in electrical engineering from Waseda University,
Tokyo in 1986 and 1988, respectively. In 1988,
he joined NTT where he was engaged in R&D of
TMN-based network management systems. In
1999, he joined NTT Comware Corp. where hewas engaged in the development of motion picture delivery systems. In 2002, he moved to NTT
Network Innovation Laboratories. His researchinterests are home networks and service management. He is a member of IEICE and the Information Processing Society of Japan.

Vol. 3 No. 1 Jan. 2005

21