Multimedia services over fiber-optic networks enhance distance learning
Schools and universities are incorporating voice, video and data communications over a fiber-based platform that lets teachers deliver lessons to widely dispersed classrooms
Aided by fiber-optic network communications, many schools and universities throughout the United States are implementing distance-learning applications to distribute educational materials and classes. These optical networks help overcome the instructional deficiencies imposed on teaching institutions because of teacher shortages, low student enrollments, overloaded work schedules, distance limitations and budget constraints.
For schools and colleges, linking facilities with a fiber-based distance-learning network presents opportunities for shared knowledge among institutions and classes, regardless of time, attendance and classroom location. If an expert in his field, for instance, is teaching a subject at one institution, the lesson can be recorded and subsequently broadcast to other schools by voice and video transmission over fiber. Alternatively, if the lesson is presented in a classroom outfitted with voice and videoconferencing technology, the class can be broadcast over fiber in real time. This setup also permits remotely located students to interact with the teacher as well as with the students at the originating location. With fiber-optic network technology, the same presentation can be shared with students virtually anywhere in the world.
Some educational institutions have implemented outreach programs to expand learning opportunities beyond the borders of urban life into rural areas. These programs bring the educational options available in urban elementary and secondary schools or on university campuses to rural campuses. Distance-learning applications over fiber-optic networks therefore allow sparsely populated institutions to share classes and expertise with less-endowed schools. In this manner, sharing enrollments saves costs and distributes otherwise unavailable classes and knowledge.
Migration to multimedia
Traditionally, school districts in the United States communicate via voice/centrex-type services over a DS-0 line at 64 kilobits per second. Network enhancements for distance-learning applications involve upgrading existing voice networks to include integrated voice, data and video transport. To accommodate increasing data requirements, local area network interconnections among schools provide access to numerous educational resources, such as CD-ROM technology, libraries, research facilities and the Internet. Key school administrative functions such as collecting average daily attendance information are also facilitated with a local area network interconnection.
With an integrated fiber-optic network platform, information resources can be concentrated in a central location and accessed from anywhere in the network. As network capabilities are extended from voice to data, the migration to interactive video is inevitable.
Interactive video provides media retrieval, access to local-programming channels and satellite uplinks. In addition, studies demonstrate that instructor and student efficiencies improve with the availability of broadcast applications for one-way information distribution to multiple sites, as well as for distance-learning applications that use two-way, interactive video sessions among multiple sites.
In tandem with service providers, school districts considering distance learning must initially evaluate existing facilities and infrastructures and determine exact network requirements. In addition, the needs of the network`s end users--students, teachers, librarians, media specialists and administrative faculty--must be evaluated. According to educational research, needs include Internet access, transparent local area network transport and interactive video.
To implement these enhanced services, school districts face multiple options, including
Leasing services from the local telephone provider
Leasing services from the local cable television provider
Building a private network.
School districts must evaluate each option to determine a cost-effective solution that meets student, teacher and community needs.
Some network providers offer services that combine voice, data and video communications. These services enhance distance-learning capabilities and provide a short payback period and a quick return on investment for the service provider. This approach also provides several benefits to school districts. Rather than purchasing services or products from multiple vendors and service providers, districts can lease a bundled service that eliminates capital investment and depreciation and defers unnecessary costs until growth justifies expansion of the modular system. In addition, school districts gain access to a fiber-based distance learning network that provides upscale services at affordable prices. Finally, as educators` needs grow to include new applications, future network enhancements are easily integrated into a fiber-based platform when new service offerings become available.
School district implementation
Typifying a school-district distance-learning application, the Keystone Oaks School District in Pittsburgh represents a progressive institution that strives to furnish students with the best education tools available through increased access to extended resources.
It therefore contracted a service provider--Pittsburgh-based Tele-Communications Inc., or TCI, in partnership with the Multimedia Systems Configuration Group of ADC Telecommunications in Minneapolis--to establish a cost-effective, multimedia-communications, fiber-optic network for distance learning.
In the existing Keystone Oaks distance-learning network, voice service was delivered by a centrex system from the local telephone service provider. Local cable-TV access service was supplied by TCI.
To serve the school district`s four sites, the newly installed private network comprises an existing TCI fiber-optic network that connects all the buildings. Voice traffic is handled by the local telephone service provider via a main network hub located in the high school.
A fiber-optic multiplexer system provides a 100-megabit-per-second backbone network among the four sites for transporting 10-Mbit/sec Ethernet, as well as 1.554-Mbit/sec T1, traffic for back-to-back private branch exchange communications. The Ethernet network is used for instructional needs and for file access, average daily attendance information, administrative tasks and miscellaneous tasks.
Amplitude-modulation, or AM, and frequency-modulation, or FM, analog video-transmission systems enable the transmission of 80 channels of broadcast-quality video and associated audio among all locations on the network. Four fibers are used to transport all voice, video and data communications among the schools. Depending on budget requirements, the fiber count could be decreased by using wavelength- division multiplexers, or WDMs.
The school district`s fiber-optic network provides:
Digital and analog transport of voice, video and data signals
Capability for multiple, simultaneous sessions
Fast access to previously inaccessible resources, including the Internet
Continuous presence, broadcast-quality video
Consolidation of voice traffic at the high school site.
Wide area network access
In addition to interdistrict requirements, the Keystone Oaks network required connections to outlying school districts and universities. It had to link to a school district approximately 50 fiber-miles away, as well as to a local university.
To accomplish these connections, a 2.4-gigabit-per-second digital video backbone system has been installed to transport voice, video and data communications over the same two fibers linked to the school districts. The consolidation of multiple types of voice, video and data for backbone use provides a cost-effective solution for interschool district requirements.
In this scenario, the school districts can present live, interactive sessions using broadcast-quality video at signal-to-noise ratios that meet medium- or short-haul National Television Standards Committee-250C requirements. High-quality video technology is important for distance-learning applications because it holds students` attention. Degraded video quality has been demonstrated to lessen student participation.
Distance-learning applications are finding widespread uses in other fields such as health care, government, business and utilities. u
Jim Cunningham is the regional director at Tele-Communications Inc., Telephony Services-East Region. The company is located in Pittsburgh.