OPERATION OF INTER-UNIVERSITY SATELLITE NETWORK: SCS
Abstract
A flexible mesh-type inter-university network was realized as SCS (Space
Collaboration System) in Japan. Multi-site operation in video conferencing
mode is easily performed sharing two or three Mbps careers. 143 sites from
120 higher education institutions including universities, colleges and
collaboration centers in Japan are using the system for 3000 hours a year. One
third is in one-man-operation mode. Two thirds are for course exchanges and
research meetings. New style of education and research activities became
possible. Data sharing mode is bEing evaluated experimentally among 6 sites.
Keywords: satellite communications, inter-university network, collaboration,
educatio
1. Introduction
Terrestrial infrastructure is bEIng constructed all over the world. Important
sites are linked with optical fibers. The se sites can enjoy the benefits of
recent information and communication technologies. But dispersed rural areas
are ironically always behind the dense urban area regarding this high-
performance infrastructure because of its thin traffics.
Satellite communication has the advantages of wide coverage and direct
accessibility to the network just by setting an earth station. We do not wait
for the growth of the terrestrial infrastructure there.
Inter-university satellite network named as SCS(Space Collaboration System)
was developed in Japan after the experimental study of multi-site satellite
workshop experiments among 10 sites in six countries for two years. It is
designed to be easy to operate multi-site sessions in a multi-career mode by
the control signal from a HUB station, which is installed in NIME(National
Institute of Multimedia Education). It has been operational since 1996 and is
used for a variety of collaborative activities among universities for about
3000 hours a year
This article reviews the SCS and results of its operation.
2. Requirements of Inter-university Network
Broadcasting of the educational program is economically efficient to
distribute educational programs widely. We can see many examples of this style
of distance education system. The keys in such cases are inexpensive receivers
and attractive programs. The number of the receivers is important and the
programs are to be produced so beautifully and attractively to be able to
gather as many participants as possible.
On the other hand, especially in the higher education where the advanced or
specialized topics are dealt with, the number of professors, students or
researchers might be small and it will be difficult to find persons concerned
in one university. The collaboration is necessary and effective.
Accordingly, the inter-university network requires following characteristics.
- two-way links
- multi-site interactivity
- easy operation
And that, these requirements should be realized economically as the
participants are many..
3. SCS configuration
How to perform the transmission in each university is important because it has
an effect on the total cost of the system. The Mbps coding scheme
was selected as the optimum in SCS. Its bandwidth was narrow enough to
suppress the channel cost and the picture quality and the coding delay
characteristics were sufficient for the real time interaction and course
exchange. The link budget calculation showed that Mbps links were
achievable for a VSAT with a m antenna all over Japan.
Licensed operators are normally required at each site. But each station can do
without them if it is a “VSAT” satisfying such conditions as follows:
- the antenna gain is below 50 dB in Ku band
- the transmission is controlled by a HUB station via satellite
- the transmission is stopped if the control fails, etc.
SCS has as one of the objectives to eliminate the requirement of licensed
operators at each university by adopting the controlled VSAT system. All the
stations are controlled by a HUB in NIME(National Institute of Multimedia
Education) in SCS.
This configuration has another advantage. Setting channels, power, time,
checking echo problems, picture received, status of all stations, etc., These
works were inevitable when we connect a station with other stations via
satellite. But automatic starting of sessions and closing became possible by
the control signals from the HUB in SCS. It facilitates the satellite use
considerably.
Several stations in a session share two or three channels in successive mode
in SCS. And in this way, the multi-site operation is performed keeping a
channel cost fixed. A session will be managed efficiently if there is a
chairman in it. Any station can be a chairman station in a session with any
number of participant stations. And a participant station can request a
channel to make a speech anytime, which is to be approved by a chairman
station. The control signals necessary to perform these tasks are all sent and
received by the HUB although some of them are triggered at a VSAT. High
flexibility is obtained by this configuration although a double hop control
requires about 6 seconds to observe the change of speaker’s station on the
channel. And these operations are performed just by a finger touch on a panel
at each station.
4. Operations of SCS
The operation of SCS was started in with 50 VSATs and a HUB. And 143
sites in 120 institutions are in the network in FY 2000. 103 sites are in
national universities, 14 sites are in private universities and others are in
colleges, collaboration institutes, etc. Furthermore, a transportable station
was also developed in 1999.
(1) Actual utilization
NIME is operating the HUB station with licensed operators, usually one
monitoring the entire network. 7 administrative staffs deal with
administrative works and mainly a few researchers study technical issues.
For the moment, available satellite channels are under budgetary constraint
although there is almost no constraint technically. A session uses two or
three channels of Mbps and two 64kbps channels for control simultaneously.
Three parallel sessions are preferentially possible to reserve. An additional
parallel session requires some negotiation in advance with a satellite channel
provider. The whole reserved schedule is open on the web page, which users
look in and reserve hours for their sessions in advance with participant’s
names. Without reservation no station can watch the session at all. It is
because the HUB controls the session and participant earth stations to
accomplish an easy and no-licensed-operator operation at universities.
SCS is being used for about 3000 hours a year for a variety of collaboration
activities among universities. Many sessions are of -2 hours in duration
between 2-6 stations. For example;
- 13 sessions of course exchange on pedagogy among three universities
- 11 sessions of research meeting on parallel computing software among three
universities
- a session of conference on pedagogy among 46 universities
- 7 sessions of forum on virtual university among 15 universities
- Periodic meeting on SCS collaboration among more than 100 universities
Almost all these sessions are operated as interactive sessions with remote
participants.
About two-thirds of the sessions are for course exchanges and joint research
meetings. The percentage of course exchange increased remarkably in 1999. This
tendency is thought attributed to the enactment to allow universities to
approve credits in the video-conferencing type distance education.
One third of the sessions are operated by each professor alone. Another third
is with students or colleagues and the last third with a staff, technical or
administrative. It indicates the easiness of SCS’s operation. More than half
sessions are with more than three sites. It indicates the system’s sufficient
capability.
(2) User’s evaluation
139 answers to the questionnaires obtained from the users in universities
installed SCS in 1996 and 1997 were analyzed to evaluate the system.
Average opinion scores on its picture quality were and in 5 grade
score for speaker’s images and material’s. The opinion score on the
picture quality saturates rapidly according to the increase of the bandwidth.
Incidentally even the high quality analog images using 30 MHz bandwidth got
scores in another experiment. As the channel fee increases linearly in
function of the bandwidth the optimum bit rate exists in the lower bit rate
regarding the opinion scores.
As for the scores about the materials sent, it is to be noted that professors
themselves, not specialists in distance education, prepare materials for
sessions in SCS. Too small characters were often observed in materials in the
earlier sessions after the operation of SCS started.
Audio quality and audio level adjustment got and and it is thought
there is no problem. The score about the switching delay was but this
problem is inevitable in a satellite system.
Opinions about the total system evaluation, such as multi-site operation
capability were higher than and the inclination to use the system again
was . These scores indicate the effectiveness of SCS as an inter-university
network..
Control is made on touch panel monitors for channel switching and selecting of
picture signals. Opinions scores abut the easiness of its operation was .
Some practice is thought required and training sessions are often held by
NIME.
(3) SCS’s effects
According to 192 comments from 62 sites, the estimated effects of SCS were
categorized in 7 groups: Independence of distance (30%), Usefulness for
students (17%), Economy of time and money (16%),Progress in R&D activities
(15%), Information exchange capability (12%), Improvement of multimedia
literacy (6%), Others (4%).
A classroom of students can now easily participates in the valuable courses or
research conferences held outside thEir universities, which was otherwise
impossible for them to participate. Facing new expressions or ideas in such
environment is estimated valuable for students.
Effective research activities became possible by easy meeting via satellite
even a small number of participants. It could give time to professors for
efficient activities. SCS remarkably increased the number of the people who
experienced distance education, videoconference with other universities and
satellite communications, which were otherwise a kind of privilege of limited
number of “rich” professors. Many people has experienced what material is
good for the remote students and came to talk about networked education. This
environment will become the basement for the future collaboration network.
The effects of SCS are attributed to three features of the network in general:
the easy connection among universities, the many participation and equality of
the sites. It shows the effectiveness of the SCS concept.
(4) Issues to be improved
Collected 252 comments were 139 users about what is to be improved about SCS.
Comments were categorized into 5 groups: SCS system (41%), Utilization of
university’s equipments (34%), Procedures to use the system in university
(10%), Support system (13%), others (2%). That is, about 60 % are the problems
about the environment around SCS systems.
As for the system, easy operability when more than three stations were in a
session was the most requested. Easier operability and the operability in
remote rooms followed. The sum of these requests amount to 50% of the comments
regarding SCS system. But soon after these surveys the remote operation
software for channel access control was developed for the remote rooms, and
three-career operation mode was also started by which more than three sites
can participate in a discussion. Far more easily
Issues to be improved outside SCS were 60% of the total comments. The most
comments were on inadequate locating of the control panels, monitors and
insufficient monitor performances. Requests for the adequate use of SCS and
adequate operation of cameras and microphones followed. Universities seem not
to be accustomed to use these systems.
Easier procedures to use the SCS facility and support system for the new users
also appeared as issues to be improved.
5. SCS transportable station
Collaboration activities have been between fixed sites up to now. But if a
place outside the classroom can collaborate more easily, new collaborative
activities will become possible. A full function SCS transportable station was
developed. Three-career operation as well as chairman function is possible at
the transportable site. All-in-one concept is adopted in its design, so three
33 inch liquid crystal monitors, audio systems, a channel controller, an AV
controller are all carried in a wagon with RF equipments as well as power
generators. It is effectively used to make a place isolated link to SCS
network.
6. Application of SCS
The more universities, the more various courses and the more variety of
activities are shared among them. Special courses that might be otherwise
difficult in a single university become possible. Small number of students or
professors in different universities can get together using the
videoconference style network.
General courses among universities will be also effectively shared. Continuous
or refresher education courses for teachers, doctors, nurses etc., for
example, are also possible. New graduate courses can be started gathering
similar faculties in different universities. Any university can start even a
“virtual” university using this network. With flexible multi-site operation
techniques in SCS, large-scale symposia have been held already in SCS, with
more than 100 universities, for example. And frequent video conferencing style
interaction strengthens and widens human networks with its easy group-to-group
interactivity. It will be forming the foundation of future collaborative
activities among universities.
7. Development of data sharing system
The service in SCS is video conferencing for the moment. As the SCS is a
digital system, data can be transmitted between sites. A proto-type system was
to be introduced to 6 sites in the SCS network, two of which are in NIME, to
evaluate the data sharing function among multiple sites. Each station can
transmit signals in one or two channels and can recEIve four channels
simultaneously. One channel is dedicated to the data transmission. One station
is approved to send the data at a time by the chairman station in a session.
The data sender can be changed station to station according to the assignment
of the chairman station.
The data lower than 384 Kbps is sent dividing Mbps channel instead of
using additional channel. Users can easily transfer data files from
station to station in a video conferencing session. Figures and tables in
detail shared or exchanged among remote participants will be useful for the
specialized or advanced discussion among universities.
8. Conclusion
In SCS, any university can promote his own activity with any number of other
universities and it can chair his sessions easily by himself. Through about
3000 hours of experiences a year, lot of know-how’s about “distance
education”, video conferencing and multi-site collaboration are being
accumulated in far more people in universities than before. It will be the
base for the future improvement of higher education as a whole.
The authors express their thanks to all the persons regarding SCS projects.
References
[1] ”Satellite Workshop Experiments using ETS-V”, ,., 44th IAF,
Graz,
[2] “Japanese Inter-University Satellite Network “SCS””, , .
48th IAF, Turin,
