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social issues that support the services. For example,
when a user uses a mobile videophone, he/she needs
to hold the device by one hand. This use situation
causes an essential restriction: A signer has to use
only one hand for signing instead of usual two-
handed signing. This posture is one of causes of
human stress and fatigue. One-handed signing also
causes difficulties in both production and perception
of Japanese Sign Language (JSL) (Kamata,
Shionome, Yamamoto, & Fischer, 2003). Another
example is a remote signed language interpreting
(video relay) service. The service inherently requires
human and social resources, in addition to
technological one.
In this report we first focus upon the display size
of mobile videophones and show the results for
perception experiments of JSL. We next make
general discussions on information/communication
services by a signed language based on the present
study results and previous experimental results for
one-handed signing (Kamata, Shionome, Yamamoto,
& Fischer, 2003). We further consider the quality of
services from the user’s point of view. We must take
into account those factors which are not considered
for the usual QoS such as user characteristics for
physical, cognitive and language capabilities
including communication situations, and human and
social factors that support the services. We then
introduce another measure, which we name User-
Based Quality of Service (UbQoS), for considering
these factors.
2 TERMINALS, MEDIA,
NETWORKS AND
COMMUNICATION SERVICES
Visual communication systems can provide new
communication opportunities to people those who
use a signed language in their daily lives (Pereira, &
Lindström, 1994). Certain features of
communication systems specify the characteristics
of these communication services.
(1) Network access means including terminal used
by a user. We assume in this discussion that mobile
videophones are used as terminals.
(2) Media type. We can now use various media for
information transmission through communication
systems such as voice, text, still pictures, and motion
pictures (video, or motion images). In this report we
only focus on videophone images (motion images).
(3) Media quality is very important parameter for
the usual QoS. Temporal and spatial resolutions are
important parameters. Another one is the time delay
between the video and its associated voice (audio-
video delay).
(4) Applications: In this report, we focus on the
videophone applications for signed language
communications, such as interpersonal
communication, a remote access to web site
information, and support services in daily life
activities such as entertainment/leisure, work,
education, and emergency.
One of the important issues for a user is whether
or not he/she can perform, in a particular situation,
an intended information/communication activity.
Quality of Service (QoS) is usually measured by
technological parameters such as frame rate and
spatial resolution for transmitted video signals. This
measure, however, does not explicitly include
factors for users and their use environments
(communication situations): Sensory and cognitive
abilities, user preferences, purpose of the activity,
and the environment in which information and
communication activities are performed. We here
show an example of voice on-demand service. Voice
on-demand services (telephone answering service)
with automatic speech recognition (ASR) are widely
used to access to information. Some hard of hearing
and deaf people can not recognise the message nor
do they respond to the message. The use situation is
very similar to that of the ordinary hearing people in
a noisy environment. Hearing people hardly
recognise the voice or speech information in a noisy
environment. From these cases, we can see that the
quality of information and communication activities
also depends on the use environments, or the use
situations.
From these examples, we introduce another term,
User-Based Quality of Service (UbQoS), for taking
into account parameters of human and social issues
that are not considered in the usual QoS. That is,
UbQoS includes parameters for quality or usefulness
of activities that a user really wants to perform in a
particular situation.
In this report, we focus upon deaf people who use
a signed language in their daily lives, and are not
able to use the usual voice/speech
telecommunication services. The aim of our project
as mentioned earlier is identifying fundamental
issues to improve communication environments
where deaf and hearing people are using mobile
videophones. In the study, we consider three types
of videophones commercially available in Japan as
shown in Figure 1. Usual mobile videophones
(Figs.1(a), and1(b)) have display size of around two
inches and weight of around 120g. PDA (Personal
Digital Assistants) type one shown in Figure 1(c)
has a larger display (3.5 inches) and is heavier than
usual ones (280g).
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