As high-speed, public-safety wireless networks move from an interesting theoretical topic generally discussed only at conferences to actual deployments, the applications that would benefit from — or be made possible by — the increased bandwidth seem endless, ranging from instant database access, field reporting and mapping to automated vehicle location, photo transmission and even streaming video.

“That's the whole point of putting in a high-speed network … so personnel can get more timely and accurate information,” said Bert Williams, vice president of marketing for Tropos Networks, which has deployed numerous Wi-Fi-based data networks for public-safety entities throughout the U.S.

However, while the efficiencies and capabilities these applications can bring to the public-safety community are obvious, their actual performance hinges on how well the high-speed networks upon which they depend work. When inevitable coverage limitations or technological glitches become a factor, ensuring that basic communications between first responders continue uninterrupted takes priority. (On the data side, first responders communicate with headquarters, not each other, today.)

Helping network designers smooth the rough spots are middleware applications that provide security, enable session continuation and allow users to switch networks automatically.

For instance, middleware vendor Padcom is in the process of installing its Total Roam in Oklahoma City, which will let first responders seamlessly switch from the city's Wi-Fi network to M/A-COM's EDACS network when they are out of range of the higher-speed network. Padcom's Total Roam software is designed not only to switch automatically to the network with the higher data throughput, it also maintains the application session to make the transition seamless.

“One of the things Total Roam does is allow you to try out new functionality while keeping the reliable existing network,” said Mark Ferguson, Padcom's marketing director. “You can try out an IP network and a non-IP network. … I think that modular aspect makes it very simple to try out new technology.”

Under the network design approved last month, Oklahoma City first responders later this year will begin using the EDACS network throughout a 1000-square-mile area that extends beyond the city limits. While the EDACS network primarily is a voice solution, it also includes a data component that provides throughput speeds of 9.6 kb/s.

Having a tried-and-true public-safety radio network as a data communications security blanket to back up the city's Wi-Fi network — consisting of Tropos Networks' equipment deployed within the 620-square-mile city border — will make it easier for Kerry Wagnon, Oklahoma City's public-safety capital projects program director to sleep at night.

“It's incredibly good to know we have that in our pocket … it's very reassuring,” Wagnon said. “I don't think we would have gone with anything [in the high-speed data arena] if there wasn't some backup. … It doesn't make a lot of sense to put all our eggs in one basket.”

While Oklahoma City's dual-network data strategy may become a model for other public-safety entities, it wasn't part of the city's plans when voters in 2000 approved a temporary sales tax to fund various public-safety capital projects, Wagnon said. The data network and the voice solution were separate items.

One difficulty in evaluating bids for the data project was the ever-changing landscape of the wireless data industry. By the time Oklahoma City selected Affiliated Computer Services (ACS) as its data-network contractor, the original proposal was three years old and did not reflect the technological advances made during that period. Wagnon sent ACS back to the drawing board.

“I told them, ‘I'm not paying $5 million for a 19.2 (kb/s) network,’” Wagnon said. “If I'm going to do that, I might as well just add some base stations to what we've already got.”

Blanketing Oklahoma City with a mesh network was considered cost prohibitive, Wagnon said. Instead, it was determined that the best solution would be to use Tropos' technology — supported by Motorola's Canopy solution for capacity injection and backhaul — to provide a high-speed network in the most active areas for the police and fire departments. The EDACS system, already selected as the 800 MHz voice solution, would be leveraged as a backup data alternative.

Testing of the data network is expected to begin in May, when Wagnon said trees will have grown leaves and coverage can be measured more accurately. Wagnon said he already is getting inquiries from other city departments to piggyback onto the public-safety data network. If there is plenty of excess capacity in the network, Wagnon said he would consider it.

One of the best aspects of the Oklahoma City data network configuration is the fact that so many access points for the network were available. The first public-safety project under the sales-tax initiative was to bolster the city's emergency-siren system, designed primarily to warn residents of tornados. The 182 sirens are mounted on 45-foot poles that “turned out to be wonderful sites for the Tropos and capacity-injector equipment,” Wagnon said.

Combined with 11 towers (800 MHz), 36 public-safety buildings and all the traffic lights in the city, the data network was deployed without any difficulty in securing sites for nodes.

“There are no planning commission issues because we already have the towers, traffic signals and buildings,” Wagnon said.

Of course, Oklahoma City is one of the 30 largest municipalities in the U.S. and has a dedicated tax to fund the construction of two public-safety networks. For Bossier City, La., with a population of 56,000, resources are scarcer, and the notion of building and maintaining a dedicated public-safety network for 110 mobile units is not realistic, given the city's budget limitations, said Bill Bell, Bossier City's information services manager.

Despite this, Bossier City wanted to participate fully in Louisiana's Thinkstream-powered data interoperability effort, which required getting a new data network after AT&T Wireless announced it would discontinue its CDPD operations — a service that 20% of the city's units typically did not use, Bell said. After determining that AT&T Wireless's GPRS offering did not provide the desired data rates, Bossier City last year opted for the 1XRTT network being launched by Verizon Wireless.

Bossier City only uses one data network, but the middleware provider — in this case, RadioIP — again plays a key role in maximizing the network's functionality. In addition to providing encrypted security and session continuity, RadioIP's software package includes a mobile data browser that allows first responders to interact via keypad with dispatchers using the city's Sungard HTE CAD solution.

Bell said this “silent dispatching” system greatly accelerates response times, noting that multiple mobile units were able to notify the dispatcher that they were en route to a recent bank robbery within 15 to 20 seconds instead of waiting for verbal communications.

“In effect, you open up voice capacity and free up the dispatchers' time,” Bell said.

Enhancing the data network also let Bossier City first responders take advantage of Sungard's field-reporting capability. With the HTE CAD solution, police officers can more efficiently file reports, which results in more time on the street and less time at headquarters.

“With the field incident module, once he finishes the report, it goes into our database,” Bell said. “It used to be that the record clerk had to take the handwritten report and try to decipher it and then the officer had to come back and verify it.”

With Verizon planning to launch an EV-DO network in June or July — increasing throughputs from 50 kb/s to 500 kb/s — Bell said Bossier City plans to begin introducing more mapping and photo functions. Combined with lower modem costs and no capital expenditures, the prospect of the EV-DO upgrade makes Bell glad Bossier City didn't try to build its own network at this time.

“If I spend $1.5 million on a network today, now I've got to sit on it for eight to 10 years to get my amortization,” Bell said. “But things are happening so fast in this industry, I'm not sure I want to be committed to a network that long. Who knows what the next three years will bring?”

Oklahoma City's Wagnon said lessons learned from the 1995 bombing of the Oklahoma City federal building convinced city officials that a dedicated public-safety communications network is a better option than depending on a commercial provider to ensure adequate capacity to handle traffic during large-scale emergencies — even if priority access is contracted. However, Wagnon acknowledged that resources play a big role in the decision-making process, saying, “Everybody has different factors to deal with and different views.”