benefits of digital video conferencing in distance education

I am doing a research project on the benefits of digital-video-conferencing [DVC] on distance education courses. I have found articles stating that synchronous communication [like chat] humanizes online learning, but since all of these studies are a couple of years old they rarely discuss using DVC equipment and software. Do you know of any studies that tackle the use and benefits of software like CUSeeMe or NetMeeting implementation in distance education? Also, since only one user can see and hear the teacher when we use NetMeeting do you know of any inexpensive multi-point DVC software?

 

It seems like DVC is only practical in two scenarios:
1) Private terrestrial networks
2) Satellite networks

In the first case, private networks (which might include virtual private networks) can be carefully designed so that all the routers and switches support some flavor of multicasting.

Without multicasting, the video stream from the source must be replicated for each student. For a single, 30-member class and 10 Mb/s compressed video (so so), you have 300 Mb/s of traffic...quite a lot but do-able on a private OC-12 optical network.

With multicasting (IP or ATM), the private network can be built such that the video stream is intelligently distributed along the way by multicasting routers/servers, reducing the bandwidth substantially. However, it is not a simple matter; for an overview of IP multicasting, see http://www.nortelnetworks.com/products/02/papers/3584.html. ATM multicasting is even harder since it doesn't have any direct support in the protocol; see http://wwwes.cs.utwente.nl/dies/archive/master/oosthoek/.

With or without multicasting, private networks aren't that attractive except perhaps for corporate training. For university DL (which I assume you're talking about), a private network just can't be built for each class; the students' locations change each term. Attempting to use the Internet would be very difficult because of the throughput required and in the case of multicasting, the lack of multicasting facilities at the many ISPs involved.

Satellite communications is a relatively easy solution since it involves a true broadcast medium. Direct broadcast satellites simplify the process for individual subscribers since the terminals are very small, or larger terminals can be placed a corporate or college sites around the country for a remote classroom setting. The uplink would be broadcast and the return path (probably voice only) would be dial or Internet IP voice.

One reason you're not likely to find a cheap multipoint equivalent to CUSeeMe and the like is because of the technical issues already discussed; there just isn't a market for such a program because the Internet does not support the technology easily. For inexpensive private network solutions for campus research, you may find some Linux solutions.

 

Of course you can use much more compressed video. Teleconferencing can be done at ISDN BRI (2B) rates. It is just a matter of deciding what is the acceptable minimum quality for a classroom setting. ISDN might provide some additional carrier-supported DVC opportunities, but probably not at a cost that you'd find acceptable.

 

sorry, I just lost the entire reply to the post. Probably just as well, it was very long.

Bob