H.323 Via Satellite Success

Bob Dixon, 04 December 2001

On Nov 27-28, good quality H.323 video conferencing via low-cost earth satellite was achieved for the first time. This occurred at the ITEC-Ohio Windows on the Future conference held in Dublin, Ohio. We have been working on this for some time, and at last success was achieved just in time for the conference. This was done by a cooperative team from OARNet, Tachyon corp, and Ohio State University.

Tachyon operates a satellite-based Internet connectivity service, which provides guaranteed bandwidth (unlike the home subscriber services) that is optimized for IP traffic. A Tachyon dish was installed on the hotel rooftop for the conference. This is a 2x3 foot elliptical dish that is easy to transport and install. It typically costs about $4K including installation, and then there are monthly charges which vary by the speed desired. The downlink speed is 1.5 Mb, and the maximum uplink speed is now 256Kb. This costs about $1100/mo. The uplink speed limited the speed of the video conference to 256Kb, and we tried various slower and faster speeds and found that 256Kb is optimum. The video and audio quality seen at the conference was very good, since that is limited only by the 1.5 Mb downlink speed. The quality at other locations was less. Fortunately this speed asymmetry is in the right direction for distance learning applications, since the class sees the best video and audio and the instructor can probably accept the poorer video and audio.

The actual conference was arranged like this. A Polycom viewstation at the hotel connected to the ethernet provided by the satellite station. The rooftop dish communicated with a synchronous satellite located over the equator, which covers North America. The satellite communicates with the Tachyon ground station in San Diego, Calif. (They also have another one in Amsterdam, for European users.) Tachyon connects to Internet 1 in San Diego, via Cox Communications, and that carried the signal to the OARNet Accord MCU in Columbus, OH and thence via a local link to a RADVision 9-port MCU, which connected via Internet2 to many participants across North America. People talked with the conference from North Dakota, Louisiana, Colorado and other places. In fact there were so many wanting to participate, that the small MCU became fully loaded and we could not at first connect from the hotel ourselves (hence the Accord MCU was brought in to organize and control things better.) It worked amazingly well, considering the I1 link from San Diego to Columbus, and the fact that this had never been done before.

The performance will soon be even better, because Tachyon will soon connect to Internet2 via the San Diego Supercomputer Center gigapop, and because Tachyon is increasing the speed of the uplink to 512Kb by the end of January. With the assistance of SKC Communications, we have loaned Polycom Viewstations and a small RADVision MCU to Tachyon for installation at their San Diego facility. It may prove beneficial to have an MCU directly attached to their network center there.

This is part of a larger effort by the American Distance Education Consortium (ADEC) to provide internet-based distance learning to rural colleges. They now have about 30 satellite dishes in operation at Indian tribal and historically black colleges around the country, and that will increase to about 80 within a year. They are now being used for things like web-based instruction, and we hope to make H.323 video conferencing available as well. The NOC for the ADEC project is operated by OARNet. The satellite data transmission system was not originally designed for such demanding applications as video and audio, so it has been a challenge to make this all work for H.323.

Future plans call for mounting Tachyon dishes on small trailers, so they can be used for special events and emergencies, and for travelling distance learning applications. Work is also under way with other projects to use Tachyon dishes in Appalachian poor areas, and eventually in Africa.