California Educational Data Processing Association
The DataBus - Vol. 36, No. 4
June-July, 1996

Spread Spectrum Wireless vs. ISDN, Part I

Networking: Radios provide alternate means of connecting sites to District's WAN.

Terrell Tucker, Panama-Buena Vista Union School District

The Panama-Buena Vista Union School District made a decision in February, 1995 to provide Internet access to its four junior high schools. Each school has a Novell LAN with a lab of 30 newly purchased, multi-media, IBM-compatible computers. The goal was to incorporate surfing the Internet into our computer science course as a new junior high requirement. The LANs have been in place for as long as five years, but no links for a WAN had been installed.

We began looking for possible ways to link the schools together. With the Education First program underway, ISDN appeared as the best solution from the very beginning. In early summer, five ISDN circuits were ordered to connect the four junior high schools and our Technology Center (teacher training center) to the District Office. We decided to purchase Cisco routers from Pacific Bell to limit our exposure to only one vendor. Pacific Bell would also be responsible for setting up and configuring the routers. The ISDN lines and equipment were installed in mid-November, barely meeting our deadline to provide Internet access starting December 1.

The Internet suddenly became a part of our curriculum and Internet access response time was good. We did, however, see a problem with our new WAN. Any access involving IPX was intolerably slow. Any attempt at file transfer or remote server management over ISDN was not feasible due to very slow speeds.

Even though IP access met our expectations, we began looking elsewhere for wide area links. Remote server management and configuration was a goal from the beginning of our endeavor. We had become convinced that ISDN would not be a permanent answer in an IPX environment.

Early February brought our first experiment--with wireless. We had investigated 10 mb microwave, but it had a high price tag. A demo of 2 mb equipment from Solectek was arranged to be installed at one of our networked elementary schools. The low level Bridge Plus units were installed at both ends with simple directional antennas. The link distance is approximately 2.2 miles with no obstructions other than a few large trees. A strong signal was immediately attained and the testing period had begun.

The first thing we did was transfer a large file, about 2.5 MB in size. An initial transfer over ISDN took over 7 minutes. The same file transfer over the new wireless link took 53 seconds. Incidentally, there was no other activity over either line when the transfers took place. Curiously enough, Internet access over the wireless link appears to be approximately the same speed as with ISDN.

As might be expected, our wireless demo did bring some bad news. We started the demo with some perceptions that have turned out to not be exactly true. We hoped to be able to place omni-directional antennas on the District Office with directional antennas at each school site. We also thought the price would be about $7200 per site. That was a bit more than we wanted to pay, but would have a two-year payoff when compared to ISDN. We then learned that Solectek's omni-directional antenna installations had some collision avoidance problems. Solectek solved this problem with a form of token passing, but added another $1000 to the cost of the equipment. All of a sudden, we were looking at approximately $8500 for equipment at the remote end ONLY!

We have purchased the Solectek equipment at a special one-time-only price and new conversations have begun with a company called Breeze Com. They offer 3 mb spread spectrum solutions. On the surface, the price is much better and many problems seem to already be solved. We hope to replace our ISDN links this summer before the free first year (Education First Program) ends. Hopefully, part II of this article will be found in the next Databus and will include some answers to our questions.

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