Tropos Debuts Vehicle Cell in Oklahoma

By Eric Griffith

September 22, 2004

The company lands its largest contract yet with Oklahoma City, and will use the venue to showcase an in-vehicle mesh node that keeps first responders connected by extending the network.

It's been several years, but the memory of the Oklahoma City bombing lingers. That feeling has lead to a full upgrade of all the public safety information technology infrastructure in the city, including computers for dispatch of first responders and all recordkeeping.

To assist with keeping cops, firefighters and EMS connected while on the road, the city is planning to cover 400 to 622 square miles (depending on who you ask) with Wi-Fi based connectivity. To do that, they're using equipment from Tropos Networks.

The $3.8 million contract with Tropos (with integrator Affiliated Computer Services out of Dallas) will consist of about 600 fixed mesh base stations that will be mounted throughout the area. Oklahoma City will also be the first city to see use of a new Tropos product, the 4210 mobile Wi-Fi cell, which will be mounted in police cruisers, fire trucks, and ambulances to keep extending the mesh network.

"In the downtown area, they'll implement the way we traditionally do: high cell density, with 10 to maybe even 20 units per square mile," says Bert Williams, vice president of marketing at Tropos. "It's the most cost-effective way to do metro broadband, but there is a cost... so in other areas, in less densely populated areas with no foot or bike patrol where there's a squad car, they'll use the mobile node."

Vehicles with the 4210 on board can extend the mesh into uncovered areas just by parking cars so there's a line back to the main mesh.

Pricing on the 4210 isn't set yet, but Williams is certain that the units will not cost more than the fixed cells. Such units can also be added easily to any existing Tropos metro network. Tropos has its service available in cities like Cerritos, Calif. (using it for pubic safety) and Chaska, Minn. (which set up a city-controlled ISP for the public). Prior to this, Tropos's largest network was in Corpus Christi, Texas, covering 19 square miles.

The unit, probably mounted in a car trunk, is powered by the vehicle's battery. That won't be a problem for most users, since first responder vehicles already tend to have an extensive amount of electronic gear running off the battery, says Williams.

If a vehicle does travel outside the mesh, it would automatically switch over to standard radio communications. According to a story in the Oklahoman newspaper, the city is also equipping vehicles with GPS so dispatchers can know their exact locations.

Backhaul on Tropos networks is provided by a high-powered 802.11b signal -- they use 802.11b on the back-end and for client connections. Specific cells on the mesh are set up as wired gateways, and connect using Ethernet, fiber, or even point-to-multipoint wireless back to the main network and/or the Internet. The company is looking at 802.11g for the future, but cites signal-to-noise issues with the protocol (requiring more 11g cells to get the same coverage) as holding them back. 11a, despite using a different radio frequency that wouldn't cause any interference with 11b/g, has more issues with getting a signal over long distances outdoors.

The Oklahoma City network will be built out this year, and should be live in early 2005. Funding is coming from the $80 million raised a few years before, when an extra sales tax was imposed in the state specifically to raise money for public safety improvements.

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