ENHANCING AND EXTENDING ENGINEERING
EDUCATION
USING DESKTOP VIDEOCONFERENCING
ABSTRACT
This paper describes electronic connectivity, videoconferencing technologies, and potential roles of desktop videoconferencing (DVC) in engineering education. Desktop videoconferencing is an exciting and affordable approach to synchronous remote communication and can be applied to improve the quality and extend the reach of education. The paper surveys different types of videoconferencing systems, with emphasis on desktop systems that communicate using the Internet Multicast Backbone (MBONE) and Integrated Services Digital Network (ISDN). The paper describes three specific application examples: lecture sharing over the Internet, industrial guest lecturer using an ISDN-based DVC system, and student outreach, also using ISDN-based DVC.
In the current period of rapid technological change and limited resources, engineering educators must find effective and efficient means to provide relevant and engaging educational experiences to traditional undergraduates, attract and retain students from diverse backgrounds, and update the technical knowledge of practicing engineers and other non-traditional students. While these needs must be addressed on multiple levels using a variety of approaches, there is an opportunity to leverage new and emerging computer and communication technology to: (i) improve efficiency by tapping into remote resources and extending access to local resources, and (ii) provide educational resources on a flexible, as-needed basis to match a variety of learning styles and needs. However, the application of new, and rapidly evolving, technologies to educational challenges is not always a simple matter; it requires an understanding of both the capabilities of technology and the educational needs followed by a careful mating and tailoring of technologies and instructional methods.
SUCCEED is one of many groups exploring this coupling of technology and education. SUCCEED, the Southeastern University and College Coalition for Engineering Education, is a National Science Foundation-funded engineering education coalition of eight engineering colleges "committed to a comprehensive revitalization of undergraduate engineering" [1]. One of SUCCEED's several goals is to "implement new communication and information technology that enhances the effectiveness and efficiency of the learning process" [1]. SUCCEED's Electronic Connectivity Deliverable Team (ECDT) was formed to address this goal [2]. The ECDT involved investigators from four of the eight coalition schools, North Carolina State University, University of Florida, University of North Carolina at Charlotte, and Virginia Polytechnic Institute and State University (Virginia Tech). The ECDT and other technology-based activities within SUCCEED have now evolved into the Technology-Based Curriculum Delivery (TBCD) Coalition Focus Team with participants from all eight schools (the four listed previously plus Clemson University, Florida State University/Florida A&M University, Georgia Tech, and North Carolina A&T State University).
This paper describes exploration of desktop videoconferencing (DVC) technology and applications at Virginia Tech conducted as part of the SUCCEED ECDT. We believe that DVC provides a cost-effective means to:
Desktop videoconferencing has features that are distinct from both traditional satellite and microwave video delivery systems and room videoconferencing systems. Desktop systems cost less to purchase and operate, are more tightly integrated with a computing environment, often provide a richer set of supporting tools such as shared electronic whiteboards and application sharing, and offer the opportunity for wide-scale distribution directly to students' desks. In general, DVC systems offer lower video quality than competing systems, but equivalent audio quality and, often, improved support for graphical communication. Studies have shown that the quality of audio and clarity of graphics are the most important factors for many distance learning applications [3, 4].
The reminder of this paper first provides an overview of electronic connectivity and defines the role of DVC in this larger suite of capabilities. Videoconferencing technology, types of systems, relative strengths and weaknesses, and example systems are then discussed. Before concluding, the paper presents results from three experiments where DVC systems were used for engineering education applications.
Electronic connectivity refers to communication via electronic means. It is critical that modes of communication be understood so that appropriate electronic connectivity technologies can be applied. Common forms of communication in education are textual, graphical, audio, and video. Communication may be one-to-one, one-to-many, or many-to-many and may be in real-time or delayed. This section describes the different forms of communication and interaction and examines technologies that support these different forms.
Modes of Communication
Figure 1 shows a taxonomy of four different modes of communication categorized by time, i.e. synchronous versus asynchronous, and space or place, i.e. local versus remote. "Same time, same place" (local synchronous) is the mode for traditional classroom instruction. "Different time, different place" (remote asynchronous) is the mode employed in asynchronous learning schemes such as World-Wide Web-based courses. Videoconferencing supports the "same time, different place" (remote synchronous) mode, although video archives can be used to provide asynchronous access to previous sessions [5].
Communication can also be characterized by interaction. Interaction may be one-to-one, one-to-many, or many-to-many. One-to-many interaction is exemplified by traditional lecturing. One-to-many interaction is also typically asymmetrical in that information flows primarily in one direction, e.g. from the lecturer to students. Interaction in office hours or in mentoring is usually one-to-one and, often, symmetric in that substantial information may flow between both involved parties. Many-to-many interaction is present in class discussions or group meetings. Videoconferencing can support all of these modes, although different systems may be more or less effective than others for a given mode.
Electronic Connectivity in Education
The use of electronic connectivity in engineering education may be evolutionary or it may be revolutionary. A revolutionary approach exploits completely new styles of learning and abandons traditional teaching methods. For the near term, it is anticipated that most uses of electronic connectivity will be evolutionary rather than revolutionary. While traditional methods must be adapted to effectively utilize different delivery methods and the relative importance of different course components may change, traditional learning modes and teaching methods can serve as templates to guide the application of electronic connectivity.
Table I shows a mapping between a variety of instructional components and some enabling technologies. The components are characterized with respect to information flow, i.e. symmetric versus asymmetric, and time of interaction, i.e. synchronous versus asynchronous.
Videoconferencing, the focus of this paper, and related technologies, such as shared electronic whiteboards and shared applications, can be applied to extend or enhance several of the instructional components where interaction is synchronous. The effectiveness of videoconferencing can often be enhanced if used jointly with asynchronous technologies. For example, use of the World Wide Web for distribution of supplemental materials provides easy access for remote students.
As indicated above, videoconferencing enables remote synchronous communication for both point-to-point (one-to-one) and multipoint (one-to-many and many-to-many) interaction and can be applied to instructional components including remote lecturing, remote office hours, and remote mentoring. However, there are different types of videoconferencing systems with a range of capabilities and costs. It is not always the case that more money buys increased capability. In fact, desktop videoconferencing systems may cost much less than room systems, but, if properly used, can be more effective for some instructional purposes due to improved integration with a computing environment. This section provides background on videoconferencing, describes communication options, presents a taxonomy of different types of videoconferencing systems, discusses relative strengths and weaknesses, and presents DVC systems used in the demonstration projects.
Background
The two-way transmission of video and audio between two or more remote sites the fundamental characteristic of videoconferencing has become much more commonplace in recent years. This is due to advances in integrated circuit technology and related software, communications, and standards.
Perhaps the single most significant factor in the proliferation of videoconferencing is the ever increasing capability of integrated circuits, coupled with software to control and exploit hardware processing. Relatively low-cost hardware video codecs (coder/decoders) can be built to perform complex operations on video to achieve orders of magnitude reduction in the data rate required for transmission. This compression, based on redundancy within a single image (intraframe compression) and correlation between different images (interframe compression), is critical to the economical transmission of video. General-purpose microprocessors are also increasingly powerful, allowing the execution of complex software, enabling computer-to-computer interaction, and, for lower quality video, software codecs.
Communications technology has perhaps not progressed as quickly as integrated circuit technology, but greater capacity at lower cost is available today than it was just a few years ago. The explosive growth of the Internet provides network connectivity at relatively high data rates on a very large scale almost universal within the academic and engineering communities. The Internet's Multicast Backbone (MBONE) enables the efficient multipoint distribution of video and other information. ISDN is now widely available and very high capacity asynchronous transfer mode (ATM) networks are beginning to be deployed. These communication options are described below.
The final contributor to the growing availability of videoconferencing are standards. Standards allow equipment from different vendors to work with each other. New standards are emerging to keep pace with new communication technologies and applications. The most prevalent videoconferencing standards are those developed through the International Telecommunications Union (ITU). H.320 is an overall standard for videoconferencing designed for use with ISDN. It uses H.261 video compression and many H.320 systems use T.120 for data sharing. Currently most, but not all, videoconferencing systems with ISDN interfaces support H.320, although they may also support proprietary schemes for connecting like units. Recently, the industry has begun to focus on H.321, H.323, and H.324, which are intended for use with Broadband-ISDN (B-ISDN), local area networks (LANs), and standard telephone service ("plain old telephone service" or POTS), respectively [5].
Communication Options
Most current videoconferencing systems use either ISDN or the Internet to transfer video, audio, and data. ATM has several advantageous features, but the availability of ATM and of products that utilize ATM is currently very limited.
ISDN is a circuit-switched network, so it is much like the standard telephone network. However, ISDN provides substantially more capacity and call control than standard telephone service. A single ISDN basic rate interface (BRI) provides two circuit-switched (dedicated) 64-kilobit per second (kbps) B channels and one packet-switched 16-Kbps D channel (referred to as 2B+D). The capacity of the two B channels can be aggregated to simultaneously carry voice, compressed video, and data. ISDN service is available in most of the U.S. and is very widely deployed in much of Europe. Equipment to interface to ISDN is also available; numerous vendors offer ISDN-based DVC systems. ISDN does have limitations, however. Its capacity is somewhat low for video applications. Image size and frame rate are necessarily reduced from broadcast quality. Some videoconferencing systems utilize multiple BRIs for a single conference to improve video quality. For example, three BRIs can be combined to provide 384-kbps capacity. Like the standard telephone network, ISDN provides point-to-point connections. Multipoint conferences require the use of a special multipoint control unit (MCU) to create a virtual multipoint network using multiple point-to-point connections. One can purchase MCU equipment or utilize fee-based multipoint services. Reference [6] is source for additional information about ISDN.
The Internet, including the LANs that form the local distribution networks for the Internet, are packet-switched networks. Many DVC systems allow connections over LANs and/or the Internet itself. There are issues in transmitting multimedia information over packet-switched networks where capacity is shared in an on-demand manner among multiple users. If network utilization is high, sufficient capacity may not be available over some links and information will be lost. This is especially critical at links between campus or corporate networks and the Internet backbone. Also, packet switching may introduce queueing delays that violate the real-time constraints of audio and video. Audio and video compression, low video frame rates, efficient multicasting to groups of computers using the MBONE [7, 8], and protocols that support real-time transport [9] can improve performance.
ATM has two features that make it attractive for videoconferencing, it supports high data rate connections, for example 155-megabit per second (Mbps) links are common, and, with some implementations, it supports quality of service guarantees that ensure that real-time audio and video information is delivered in a timely manner. For example, the Net.Work.Virginia ATM wide area network [10] is routinely used for videoconferencing. Output from a standard codec is adapted to ATM using a cell access multiplexer. It is likely that future DVC products will take advantage of ATM to provide high quality video and rapid data transfer. Currently, however, ATM service is not widely available and high data rate services tend to be rather expensive unless shared among many applications and organizations.
A Loose Taxonomy of Videoconferencing Systems
One can loosely categorize videoconferencing systems into four categories based on their complexity, i.e. cost, and underlying communications mechanism.
Room or "Roll-Around" Videoconferencing Systems. Room videoconferencing systems provide two-way audio and video, usually using three ISDN BRIs (384 kbps) or higher data rate connections. Since ISDN or other point-to-point links are normally used, sessions with more than two sites require the services of a multipoint conferencing unit. Room systems can support computer display input, for example using an NTSC scan converter, and may also support the interactive use of software as an option. Equipment costs from $25,000 to $75,000 or more per site. ISDN charges vary, but point-to-point connections usually cost around $90 per hour for three BRIs and multipoint service costs about $160 per site per hour for three BRIs.
ISDN-Based Desktop Videoconferencing Systems. These system leverage personal computer (PC) capabilities for two-way video and audio using, typically, a single ISDN BRI. DVC systems are built into a computer, while room videoconferencing systems often have a computer built into them. This "visibility" of the computer in a DVC system explicitly integrates conferencing and computing. Typical systems supports shared whiteboards for collaborative annotation, shared applications for joint viewing and control of applications, and file sharing. Equipment beyond the computer itself costs about $1,000 to $3,000. Since DVC systems use just one BRI, communication costs are about one-third of those of room systems, i.e. about $30 per hour for a point-to-point connection about $55 per hour per site for a multipoint session.
Internet-Based Desktop Videoconferencing Systems. Like the ISDN-based DVC systems just described, these system leverage PC or workstation capabilities for two-way video and audio, but use the Internet or other packet-switched network for communications instead of ISDN. Special-purpose hardware or software executed on a very high performance processor is used for video compression. The video compression card with software typically costs about $1,000 or more. Incremental communication costs are zero, although increased network traffic can lead to increased expenses for an organization's network infrastructure.
Internet-Based "Personal" Desktop Videoconferencing Systems. By using inexpensive video capture boards or cameras with built-in video capture, standard computers can be used to provide low frame rate video, highly compressed audio, and collaborative tools. The audio and video quality of these systems is inherently lower than those found in ISDN- and high-end Internet-based DVC systems. However, the collaborative tools may be as powerful, or even more powerful, than those found in other systems. Equipment costs may be as little as $100. Like high-end Internet-based DVC systems, the incremental communication costs are zero. However, the impact of "personal" DVC systems on overall network utilization tends to be less than the impact of higher-end systems since the data rate is lower.
Comparisons
The selection of a videoconferencing solution varies according to particular instructional needs, teaching styles, and organizational and other constraints. The following criteria are considered important if videoconferencing is to be widely deployed, employed in novel ways that are both effective and efficient, and supportive of engineering education which is heavily computer-based.
Tables II through V provide qualitative comparisons of the four different types of videoconferencing systems by summarizing their relative advantages and disadvantages.
| Advantages | Disadvantages |
| Good to very good video and audio quality
Video and audio quality does not vary Supports well-understood lecture and meeting models H.320 standard enables interoperability |
Inherently point-to-point; MCU needed for
multipoint conferencing
High system cost High communication costs Integration of computing is often limited |
| Advantages | Disadvantages |
| Good audio quality
Video and audio quality does not vary Low system cost Moderate communication charges Excellent integration with computing (shared whiteboard and applications) H.320 standard with T.120 standard for data enables interoperability |
Moderate video quality (low frame rate and
small video images)
Non-traditional lecture or meeting models needed for effective use Inherently point-to-point; MCU needed for multipoint conferencing |
| Advantages | Disadvantages |
| Internet connectivity is widely available
Excellent support for multipoint conferencing with multicasting Low system cost, software often free No incremental communication charges Excellent integration with computing (shared whiteboard and applications) Software versions for multiple platforms |
Audio and video quality is highly variable,
ranging from good to unusable
Non-traditional lecture or meeting model needed for effective use Places a burden on already overloaded Internet connections |
| Advantages | Disadvantages |
|
|
While there are many important applications for which room videoconferencing systems are uniquely qualified, there are three key differences between room systems and many desktop systems that led us to focus on desktop videoconferencing.
In addition, immediate use of DVC systems can provide a knowledge base to improve use of
more expensive room videoconferencing systems and future DVC and new videoconferencing
systems with enhanced capabilities.
Example Systems
To date we have extensively used two different desktop videoconferencing systems.
The first is an Internet-based DVC system based on a Sun Microsystems SPARCstation 5 workstation running the Solaris operating system with a Sun Video card. This configuration supports different software packages. Freely available conferencing tools for the MBONE [11] have been found to work well. Specifically, we have made extensive use of SDR (session director), VIC and IVDS (video), VAT (audio), and WB (whiteboard). Figure 2 shows an example of WB, the shared whiteboard. We have also successfully used the commercial Sun ShowMe package that supports video, audio, shared whiteboard, and shared applications.
The second DVC system is an ISDN-based Intel ProShare Video System 200 running on a standard 120-MHz Pentium personal computer with Microsoft Windows 95. Features include two-way audio and video, shared whiteboard using a notebook metaphor, application sharing, and file, clipboard and image exchange. The Intel ProShare system uses a single ISDN BRI to transfer video, audio, and data. The same system can also be used for videoconferencing on a local area network.
We have used, and continue to use, the two systems described above for a variety of conferencing tasks, experiments, and demonstrations. Three specific applications directly related to engineering education are described below.
Remote Lecture Sharing
Virginia Tech and the University of Florida collaborated to share two lectures on March 19 and April 2, 1996 for a graduate computer networks class. The lectures were carried on the Internet using standard MBONE tools (SDR, VIC, VAT, WB) [11] running on Sun Microsystems workstations. Copies of the instructors' slides were made available in advance on the World Wide Web. The demonstration explored the potential of this type of resource sharing using the Internet.
Hardware, software, and networks provided the electronic equivalents of traditional lecture components. A video stream, audio stream, and display of presentation graphics provided the asymmetrical one-to-many information flow from the lecturer to the students. Return audio and video streams provided symmetrical many-to-many communication for student interaction. Given equipment and space constraints and the desire to experiment, two different classroom configurations were used. Students at Virginia Tech were in a computer laboratory, with one or two students sharing each workstation. Students at Florida were in a standard television classroom with a video projection system.
Since only two sites were involved in the shared lectures a non-multicast, or point-to-point, "tunnel" was established between the local area network in the workstation laboratory at Virginia Tech and the classroom at Florida. At Virginia Tech, multicasting eliminated the need to send separate video, audio and graphics streams to each of the local workstations.
Use of the WB shared whiteboard illustrates how available technology can be used to effectively deliver adapted instructional material. For the lecture originated at Virginia Tech, lecture slides began as a Microsoft PowerPoint presentation. The PowerPoint presentation was "printed" to a PostScript file and the PSSPLIT tool was used to create a set of PostScript files with one file corresponding to one slide in the original PowerPoint file. The LZPS tool was then used to create compressed PostScript files. WBIMPORT [11] (whiteboard import) was used to control the slides. Using WBIMPORT, slides were preloaded to all remote workstations from the instructor's workstation. The instructor was then able to move between and synchronize the slides at all workstations. (Figure 2 shows an example of a PowerPoint slide displayed using WB as part of another presentation.)
For the lecture originating at Virginia Tech, there were three groups of students. The group at Florida saw the lecture delivered over the Internet while in a fairly traditional classroom environment. A second group of students at Virginia Tech saw the lecture delivered over a local area network seated at workstations in a laboratory separated from the instructor. The third group attended a traditional "live" lecture by the same instructor, covering the same material, using the same lecture slides. Students in the Internet-delivered lecture completed a questionnaire after each lecture and all students took a quiz to assess retention and understanding of lecture material. Quiz results showed no statistical difference in performance among the three groups, although the Virginia Tech students in the "live" lecture had the best scores, followed by the students at Florida, followed by the Virginia Tech students in the workstation laboratory. Survey results, however, indicate dissatisfaction with audio and video quality, which was rather poor. A complete discussion of the evaluation is available [3, 4].
This dissatisfaction points to the fact that the Internet connectivity between Virginia Tech and the University of Florida was simply inadequate for sustainable real-time video-based distance learning, at least in the spring of 1996. Congestion on the Internet, likely at the links in place in between Virginia Tech and/or Florida and their Internet access providers, led to frequent packet loss and, thus, unacceptable audio and video degradation. However, classes taught between North Carolina State University and the University of North Carolina at Asheville demonstrate that Internet-based synchronous distance learning is feasible provided that Internet capacity is sufficient [12].
Guest Speaker from Industry
A second demonstration brought a guest lecturer from the Intel Corporation in Hillsboro, Oregon into a senior-level telecommunication networks class at Virginia Tech on April 26, 1996, to speak, appropriately enough, on the topic of videoconferencing. The lecture used Intel ProShare Video System 200 and an ISDN BRI connection. An LCD projector was used at Virginia Tech to display the computer's screen to 27 students in a conference room at Virginia Tech. This demonstration showed the potential to involve industry experts in the classroom without requiring them to travel to campus.
ProShare's two-way video and audio provided a mechanism for the lecturer and the students to see and hear each other. ProShare's shared notebook was used to display and control a graphical presentation. ProShare allowed data to be exported from a standard Microsoft Windows application, in this case Microsoft PowerPoint, to a file that was read into the notebook. Once in the notebook, the lecturer was able to control and annotate the slides.
The demonstration showed that a low-cost DVC system could be used to enrich a class using a "virtual" guest lecturer. The result was considered to be very successful, with a survey of students showing that 22 of the 27 students in the class considered the lecture to be effective. The guest lecturer was also pleased with the opportunity to speak to the students and the ease with which her presentation could be adapted to the system.
Of the three forms of information that were conveyed, video, audio, and graphics, video quality was the poorest and was not as good as would be expected from a traditional satellite-or microwave-based distance learning system or room videoconferencing system using three ISDN BRIs. The frame rate was about 10 frames per second, but was acceptable for this style of lecture. The video provided a personal connection, while most of the instructional content was conveyed using audio and graphics which were both of high quality. The only flaw in the audio was the need to manually mute classroom audio due to echo problems. This problem is easily eliminated with a better sound system. The graphics were designed for this style of delivery and were extremely clear and effective.
Student Outreach
In the third demonstration project, three officers of the Virginia Tech chapter of the National Society of Black Engineers (NSBE) were interviewed by a panel of three eighth graders from St. Pius V Parish School, an inner-city middle school in Jacksonville, Florida. The demonstration showed how DVC systems allow unique interaction and outreach that would not otherwise be feasible. An ISDN BRI connection carried two-way audio and video between an Intel ProShare Video System 200 at Virginia Tech and a PictureTel desktop system at St. Pius V. Both systems support the H.320 standard. The three NSBE officers sat at the ProShare computer and used a Coherent CallPort microphone/speaker with echo cancellation for audio, as shown in Figure 3. The three panelists at St. Pius V shared a microphone and all students viewed the session on a monitor.
The NSBE officers at Virginia Tech and the students at St. Pius V were all enthusiastic and pleased with the results. None of the participants had experience with this type of technology. During the first several minutes of the session, there was considerable focus on the system and the technology. After that, the "gee whiz" aspect of the session faded and the students had a productive and sincere interchange for about 40 minutes. Sister Elise Kennedy, principal, said the following: "These engineering students had a great impact on our students, from afar. They could be seen and heard. They were 'in' the library with us. Yet they were in college in a distant state. Through distance learning technology our students were able to see and talk to three of the best role models to 'visit' our school this year. They said everything our students needed to hear. They made a difference!"
CONCLUSIONS
This paper described desktop videoconferencing and its role in providing "electronic connectivity" for engineering education. Three specific demonstration projects were described. Two of the projects, bringing a guest lecturer into the classroom and a student outreach activity, were highly successful. The third demonstration, using the Internet to share lectures, met with success in conveying information but was unsuccessful with respect to student satisfaction due to the poor audio and video quality.
Several issues must be addressed in order to use DVC effectively. First, the instructional model must be carefully considered and a match must be made between instructional techniques and technology. DVC is particularly well-suited for computer-integrated instruction where presentation graphics and other software packages are used in the lecture. It is not well-suited for instruction where high quality video or rapid visual interaction is critical.
Secondly, cost is, of course, an issue. The economies of digital technology will continue to reduce the cost of DVC equipment. For the near future, communication costs are likely to be the dominant consideration. Where existing Internet connectivity is good, Internet-based DVC is cheap, provides multipoint connectivity, and is highly effective provided that the instructional methods are appropriately mapped to technological capabilities. However, for many connections, the Internet simply does not provide adequate quality of service to support effective videoconferencing. In these cases, ISDN is the common alternative. Monthly and per minute ISDN charges increase the cost of DVC. Where multipoint connections are needed, costs are further increased by per minute charges for a multipoint conferencing service or by the approximately $50,000 and up cost of a multipoint control unit. ATM services are beginning to become available on a limited basis and can be used to provide improved Internet service and to directly support videoconferencing in native mode.
It is clear that technology will improve and become more affordable. In the not too distant future, traditional and non-traditional students will have the capability to receive lectures and interact with faculty and other students in their homes and workplaces over the Internet or through other communication services. It is important that educators investigate DVC technology and determine how and when to use it effectively. We must make informed and considered choices, not blindly embrace or reject the technology.
SUCCEED's Electronic Connectivity Deliverable Team has a World Wide Web site at http://www.visc.vt.edu/succeed/ that describes electronic connectivity technologies and applications, including DVC. A product survey is maintained by ECDT participants at North Carolina State University at http://www3.ncsu.edu/dox/video/survey.html.
Funding for this work was provided by the National Science Foundation to SUCCEED (Cooperative Agreement No. EID-9109853). SUCCEED is a coalition of eight schools and colleges working to enhance engineering education for the twenty-first century. The author gratefully acknowledges the contributions to this area of work within SUCCEED by faculty investigators T. K. Miller at North Carolina State University, H. A. Latchman at the University of Florida, I. N. Bodur and J. L. Grant at the University of North Carolina at Charlotte, and R. C. Williges, M. B. Rosson, and J. G. Tront at Virginia Tech, and by graduate students R. D. Hudson, J. K. Kies, and D. C. Lee at Virginia Tech, L. A. Rettinger and K. L. Hewitt at North Carolina State University, and S. I. Ali and M. Ramachandran at the University of Florida.
Product names referenced in this paper are trademarked. The paper refers to products with which the author has experience. No endorsement is implied. Any reference to costs is for illustrative purposes only. The opinions expressed in this paper are those of the author.
[1] SUCCEED Coalition: Engineering for the 21st Century, at http://succeed.engr.vt.edu/.
[2] SUCCEED: Deliverable Team 5 Electronic Connectivity Home Page, at http://www.visc.vt.edu/succeed/.
[3] J. K. Kies, R. C. Williges, and M. B. Rosson, "Evaluating Desktop Video Conferencing for Distance Learning," Computer and Education, to appear.
[4] J. K. Kies, R. C. Williges, and M. B. Rosson, "Controlled Laboratory Experimentation and Field Study Evaluation of Video Conferencing for Distance Learning Applications," Hypermedia Technical Report HCIL-96-02, 1996, at http://hci.ise.vt.edu/~hcil/htr/HCIL-96-02/HCIL-96-02.html.
[5] D. J. Gemmell and C. G. Bell, "Noncollaborative Telepresentations Come of Age," Communications of the ACM, Vol. 40, No. 4, pp. 79-89, April 1997.
[6] D. Kegel, "Dan Kegel's ISDN Page," at http://alumni.caltech.edu/~dank/isdn/.
[7] S. Deering, "Host Extensions for IP Multicasting," RFC 1112, August 1989.
[8] M. Macedonia and D. Brutzman, "MBONE Provides Audio and Video Across the Internet," Computer, Vol. 27, No. 4, pp. 30-36, April 1994.
[9] H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications," RFC 1889, January 1996.
[10] Net.Work.Virginia at http://www.networkvirginia.net/.
[11] Merit Network, Inc., "MBone Software Archives," at http://www.merit.edu/net-research/mbone/.archive.html.
[12] NCSU/Fujitsu Network-Based Education Project, at http://www3.ncsu.edu/dox/NBE/.
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