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 1.5 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, education

1. introduction

terrestrial infrastructure is being constructed all over the world. important sites are linked with optical fibers. these 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 1.5 mbps h.261 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 1.5 mbps links were achievable for a vsat with a 2.4 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 oct.1996 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 1.5 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 1.5-2 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 3.9 and 3.3 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 4.2 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 3.9 and 3.6 and it is thought there is no problem. the score about the switching delay was 2.7 but this problem is inevitable in a satellite system.

opinions about the total system evaluation, such as multi-site operation capability were higher than 4.0 and the inclination to use the system again was 4.2. 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 3.2. 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 1.5 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, oct.1993

[2] “japanese inter-university satellite network “scs””, , . 48th iaf, turin, oct.1997