By the end of the year, Union Public Schools of Tulsa, Okla., will be one of the first public school systems in the country to use a fully integrated microwave network. The wireless network will enable the district to provide cost-effective voice, video, and data transmissions to and from its 15 school buildings while saving thousands of dollars in leased line charges.

The microwave network uses ultrahigh-frequency (18 and 23 GHz) digital radio signals to transmit information from point to point over short (5- to 10-mile) hops via line of sight. Microwave’s 45 Mbps–about 30 times faster than a T1 line–offers a huge advantage in bandwidth, according to Lee Snodgrass, information technology director for the district.

“In order to provide teachers and students with the technology tools they need–voice, video, and data transmission–an integrated microwave network is the best route to take for the money,” Snodgrass said.

The technology requires an antenna to transmit and receive signals and a microwave radio to translate and route them through the appropriate channel of a building’s local area network.

Union contracted with Tulsa-based network design firm Baxsys and Tadiran Microwave Networks of Houston, Texas, to install the system. Surveys of the district indicated that Union would need a 10- to 25-foot mast on top of each building, plus a 120-foot tower at the district’s main service center through which all signals are routed.

Saving big with ATM

While other districts have used microwave technology to transmit data across a wireless network, Union’s approach–an integrated microwave network transmitting voice, video, and data–is fairly unusual, Snodgrass said.

To accomplish its mission, Union is using asynchronous transfer mode (ATM) technology in conjunction with the network. ATM takes the available pipeline and segments it, transferring information in smaller packets of uniform size so voice, video, and computer data can travel over the same network while no single type of information hogs the bandwidth.

Each microwave radio plugs into an ATM system that splits information into its proper channel–private branch exchange (PBX) lines for voice, for example, or classroom hubs for data.

The microwave network cost the district between $30,000 and $35,000 per school for the antenna, radio, and power supply, plus another $70,000 for the tower and equipment at the main service center. The ATM gear cost an additional $750,000, Snodgrass said–but the district expects to reap big savings on its monthly leased line charges.

“In the long run, it’s far more affordable to consolidate the voice, video, and data traffic than to segregate it three ways,” added Brad Baxter of Baxsys.

With its microwave network, the district will be able to provide each school with 23 phone lines while saving about a third of its yearly $150,000 phone bill, Snodgrass said. The wireless network means the district won’t need as much infrastructure–just lines to the central office instead of to each school.

The same holds true for data lines, Snodgrass said. To achieve the same speeds, the district would need to lease T3 lines for each building at a cost of up to $3,000 per site per month, he said.

All Union schools are using the network to transmit data and will be using it for voice by May. Video transmission over the network has been tested successfully and will be available later in the 1999-2000 school year.

As part of its long-term technology plan, Union has provided network connections in all classrooms and offices. Students have access to computers and other instructional technology, and all teachers have classroom computers. More than 96 percent of the staff has received extensive computer training, and more than 800 employees will be attending internet training next month.

Union Public Schools

http://www.unionps.org

Tadiran Microwave Networks

http://www.microwavenetworks.com