Letters

Image Systems Using RFID Tag
Positioning Information
Shin’ichi Nakagawa†, Ken’ichiro Soh, Shin’ichi Mine,and Hiroshi Saito
Abstract
We have developed a system that automatically selects images from particular cameras based on RFID
(radio frequency identification) tags that identify individual persons or objects, thus enabling each user
to receive desired images via IP networks. For example, if an RFID tag is inserted in the nametag of akindergarten child and several cameras are installed in the kindergarten, the system automaticallyswitches the transmitted images according to the child’s movements so that the parents can watch theirown child from home or the office.

1. Introduction
ADSL and other broadband services are proliferating at an increasingly rapid pace, and the distributionof stored image contents has now begun. Users canobtain network cameras at an affordable price, andwe can expect to see a steady increase in the types ofimages that can be used, including live images sent byvideo phone. We expect that there will be an increasein demand for simpler selection of images that are ofinterest to users from among the huge number ofavailable images.
† NTT Service Integration Laboratories
Musashino-shi, 180-8585 Japan
E-mail: nakagawa.shinichi@lab.ntt.co.jp

There are various methods for obtaining positioning information such as PHS (personal handy-phonesystem), GPS (global positioning system) and RFID
(radio frequency identification) tags. RFID tags comein active (with built-in battery) and also passive types.
Table 1 shows a simple comparison of these four
methods. RFID tags can be used outdoors, but theinstallation of receivers has not yet reached the pointof being a true infrastructure, and applications arelimited to spot usage in the immediate vicinity of thereceivers. Passive RFID tags can only be used in close
proximity to the receiver, while active RFID tags
have a limited battery life. PHS is basically designed
for outdoor use, but antennas are now being installedindoors, mainly in public facilities, providing a broad
scope of applications. Even so, the positioning accu-Table 1. Comparison of position identification methods.
Position identification
accuracy, etc.

Indoor useNotes

Active RFID tag

Can be used withinapprox. 10 m dia.

GoodRequires internal battery in tag. Can be used for several years,depending on transmission intervals.

Passive RFID tag

Operates at close
range (1 m or less)

Good

Powered by external radio waves, so frequency and distance
between tag and receiver are limited.

PHS*

Position identification
accuracy: about 100 m

Fair

Positioning accuracy is rough. Can be used indoors in somecases, depending on antenna installation conditions.

GPS

Position identification
accuracy: about 10 m

Poor

Cannot be used indoors. Good positioning accuracy whencorrected using map information.

*When using NTT DoCoMo’s Imadoko service (fee required)Vol. 1 No. 7 Oct. 2003

79Lettersracy is around 100 meters. GPS can only be used outdoors. Each of these methods thus has limitations, somethods must either be selected according to the service content, or combined so as to complement one
another.
Our developed system is unique in the sense ofbeing a combination of image systems and RFID systems.
2. Image systems using RFID tag positioning
information
Existing image systems cannot identify the subjectin images. Our system can identify the subject among
several dozen people. It enables users to select camera images of the subject, who is identified by anactive RFID tag placed on him or her, and to view theimages via the Internet on suitable terminals. In thesystem introduced here, we chose the active RFID tag
system as the most appropriate method for use inindoor facilities and within the range of the cameras
being used (approximately 10 meters in diameter).
Here we explain the functions for use in a kindergarten as a typical application.
2.1 Image selection
Figure 1 shows an example of a specific applicationof how this system handles images in a kindergarten.
Cameras, receivers, and management servers areinstalled in the kindergarten classrooms and otherlocations. The children are given RFID tags, whichmight be installed in their nametags. The RFID tags
transmit radio signals at regular intervals, including
an ID code known as RFID. The signals are picked up
by receivers installed throughout the kindergarten,
and the RFID is sent from the receiver to the management server. The receiver picking up the radio signal changes as the child moves around the kindergarten, so the management server can track whichchild (RFID) is in which area. Parents can watch theirchildren by logging into the system via the network
using an account and password issued in advance,
using the browser on their PC at home or at work.
A parent can view his or her child from the nearest
camera. Figure 2 shows a screen for the server administrator managing cameras installed in four locations,

Selected user
nameImage showing thesubject* with a tag ishighlighted by a blue
frame. This is theimage that is shown
to the parent.
* For this demonstration,
we used a teacher
rather than a child.

Fig. 2. Example of management screen.
ParentImagetransmission

LAN

Management server

ReceiverClassroom AT

Image selection function
Camera for specified
subject selected according
to reception conditions

ReceiverTCameraClassroom B
ReceiverClassroom CT

RFID tag

Fiber access

CameraCameraDevice management functions
Relationships between RFID
receivers, cameras, etc.,
and installation location
management

IP network

Dangerous area;
notification whenchild enters

User management functions
Correspondence between tag
and child
Correspondence between
child and parent
Movement history
Tag’s movement
history displayedscesr acFibe

T

ParentADSL

Imagetransmission

Safetymanagement

Teacher

Alarm function
Sounds in response toreception conditions

Fig. 1. Typical system configuration in kindergarten.

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Letters

such as the shoeboxes andthe lockers. Parents see
only one image (in thiscase the bottom left one),which is automaticallyhighlighted with a blue
frame on their screen.
(For this demonstration,
we used a teacher rather
than a child.)

Selected tagged user
Monitoring period
Time of detection
Place of detection

2.2 Movement history
Other functions besides
the automatic selection of
the live camera are“Movement History Display” and “Alarm Function”. The information
received from the RFID tag is stored in the system ina log. Figure 3 shows a screen image of how thisinformation is displayed in chronological order(Movement History). This log shows movement
behavior at a glance; for example, which RFID tags
(i.e., which children) have been in which area and for
how long, as well as how many times a subject went
to each area. If a data analysis function is added tothis system, it will be possible to use this data in awide variety of applications, including analyses ofcorrelations between tags and statistical analysis of
the time spent in each receiver area or the number ofentries and exits. Some of these applications aredescribed below.
2.3 Alarm function
It is possible to have an alarm sound according to
the reception conditions of a given RFID tag. For
example, the alarm could sound if the tag is detectedby a specified receiver or when the tag cannot bedetected by any of the receivers. Figure 4 shows anexample of this system (alarm settings). For a kindergarten, the alarm could be set to sound when any
child approaches one of the exits or the stairs to theroof. However, the RFID tag system itself is notdesigned for applications where lives may be at risk.
Such applications of this system should be confined
to use as a complementary function.
3. Potential fields of application
The system itself is a general-purpose system andcan be applied to a wide range of fields besides
kindergarten and daycare settings. Table 2 shows sevVol. 1 No. 7 Oct. 2003

Fig. 3. Movement history.

Check box matrix
for setting alarms

Places where user
will be monitored

Tagged users

Fig. 4. Alarm settings.

eral specific examples.
(1) Home monitoring (pets, perimeter of house):
An RFID tag can be attached to the collar of a cat
or other indoor pet, and a camera and receiverinstalled inside the house, so that the owner canwatch the pet while away from home. An RFID tag
can also be attached to the family’s key-holders,
and receivers can be installed in the living room andother locations and cameras can be installed in thefront hall and other parts of the house. When no signals are received from the RFID tags — that is,when nobody is home — the home owner or a security company can remotely watch images of theperimeter of the house.
(2) Social welfare facilities: Residents have RFIDtags, so relatives and others can watch an elderly
person there. Secondary applications by the facilities themselves are also possible, for example
detecting residents who have wandered off thepremises based on locations of the RFID tag signals. Depending on the requirements of the viewers, the range of camera images can be adjusted, ora power switch can be added to the RFID tag itself,
so if the person being monitored wants some priva81

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Stored images

Live Images

Table 2. Typical applications.
Application

RFID tag subject

Receiver, camera
installation locations

Image viewing
location and viewer

Home security

PetHomeOutside the home

Home security

Keyholder

Perimeter of house(camera)

Security company oroutside the home

Building
monitoring

VisitorRestricted areas

Security personnel

Shared object
management

Shared object

Management or
usage location

Shared object
manager or user

Commemorative
video production

Visitors

Entertainment facilities,
attractions, etc.

Person entering

Efficiency
Improvement

Employee

Shops and workplaces

Manager or head
office employee

cy, he or she can switch it off.
(3) In public facilities: RFID tags can be incorporated into ID badges for visitors, enabling security
personnel to detect accidental entry by visitors into
restricted areas in real time and to monitor images
from a safety management perspective.
As an extension of these applications, in addition
to monitoring live images, these images can be
stored for a period of time, enabling the following
types of applications by matching the imagesagainst the RFID tag reception logs.
(4) Management of shared objects: An RFID tag
can be attached to a shopping cart or other sharedobject and a receiver and camera installed in themanagement location, so that when a change in thesignal status of the RFID tag—that is, movement of
the shared object—is detected, it is possible toaccess images for the time when movement tookplace.
(5) Entertainment facilities: Cameras and receivers
are installed at attractions in indoor facilities, andvisitors have RFID tags. A commemorative video
for each visitor can then be created by gathering relevant RFID images from the images stored
throughout the day. These images could be edited in
combination with images from parades and otherevents.
(6) Shops and workplaces: Cameras and receivers
can be installed in shops and workplaces and theemployees given RFID tags. In addition to managing the attendance of each employee, by storing
images and recording movement of the RFID tags,

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System application
conditions

Can be used

Requires additional function
for processing stored images
Requires additional function
related to analysis process

it is possible to analyze the time required to complete tasks or the variation in required time among
various employees. This information can also be
used as basic data for increasing work efficiency orfor designing more efficient office layouts.
4. Further study
To adapt the systems to handle a large number ofusers, we will reconsider how to distribute the server
load, or which users connect to which servers, andhow to manage the total load. If the systems are to be
applicable to security services, they should be morereliable and fault tolerant.
5. Conclusion
We have developed image systems combined withpositioning systems. These enable us to create newservices for broadband users. The number of live
images is expected to increase even more in thefuture, with mass media images of interest to many
people and individual images targeting a small number of users (e.g., images from cameras installed inkindergartens and daycare centers). The provision ofattractive images as well as convenient and easy-touse services holds the key to the future proliferationof broadband. The RFID tag image system introduced here will contribute to the further popularization of broadband applications, though it needs to beimproved.

NTT Technical Review

Letters

Shin’ichi Nakagawa
Senior Research Engineer, Information Sharing Service Network Innovation Project, NTT
Service Integration Laboratories.
He received the B.S. degree in physics fromSaitama University, Saitama in 1987 and theM.S. degree from Chiba University, Chiba in
1989. He joined NTT in 1989. He is a member ofthe Institute of Electronics, Information andCommunication Engineers (IEICE).

Shin’ichi Mine
Senior Research Engineer, Kyushu Laboratory, NTT Service Integration Laboratories.
He received the B.E. and M.E. degrees fromKyushu Institute of Technology, Fukuoka in
1988 and 1990, respectively. He joined NTT
Human Interface Laboratories in 1990 andengaged in the development of ISDN terminalsystems, technical support for ISDN network services, and the development of pay phone systems
using smart cards until 1999. Since 1999 he has
been creating new services using the broadband
network in Fukuoka, Japan. His present researchinterests are broadband communication systems
that help people create new ideas easily.

Ken’ichiro SohSenior Research Engineer, Kyushu Laboratory, NTT Service Integration Laboratories.
He received the B.E. and M.E. degrees in information engineering from Kumamoto University,Kumamoto in 1989 and 1991, respectively. In1991, he joined NTT Telecommunication Networks Laboratories. He worked on multimedia
quality assessment and multipoint videoconferencing service. He is a member of IEICE and theAcoustic Society of Japan.

Hiroshi Saito
Senior Research Engineer, Supervisor, Information Sharing Service Network Innovation Project, NTT Service Integration Laboratories.
He received the B.E. degree in mathematicalengineering, the M.E. degree in control engineering, and received Dr.Eng. in teletraffic engineering from the University of Tokyo in 1981, 1983,and 1992, respectively. He joined NTT in 1983.
He received the Young Engineer Award ofIEICE in 1990, the Telecommunication
Advancement Institute Award in 1995, and theexcellent paper award of the Operations ResearchSociety of Japan (ORSJ) in 1998. Dr. Saito is afellow of ORSJ, a senior member of IEEE, and amember of International Federation for Information Processing WG 7.3 and IEICE.

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