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Traffic signal enhancements enable wireless public safety network

March 13, 2006

4 Min Read
KC Green Lights Wireless

Sometimes innovation emerges in unlikely places.

That's the case with Operation Green Light, a regional traffic control program administered by the Mid-America Regional Council, an association of city and county governments for the bi-state Kansas City area. Designed as a technological upgrade to improve traffic flow across the twin cities of Kansas City, Mo. and Kansas City, Kan., Operation Green Light has had an unexpected and beneficial consequence: the establishment of one of the nation's most advanced metro public safety wireless networks, in Lenexa, Kan., about 12 miles southwest of Kansas City.

Built on broadband wireless equipment from Alvarion Technologies Ltd. (Nasdaq: ALVR), through a contract with the Regional Council, the Lenexa network includes connections to fixed locations running over the unlicensed 5.3GHz and 5.8GHz frequency bands and backhaul over the 4.9GHz band, which is licensed specifically for public safety applications, as well as mobile broadband links in the 900MHz band to public safety vehicles. The genesis of the network, says Michael Lawrence, CTO for the city of Lenexa, a 30-square-mile suburb with around 45,000 residents and a daytime workforce nearly double that, was the effort to build and install an intelligent traffic signal (ITS) system.

"We're probably in the top 5 percent of the nation for this type of deployment," explains Lawrence. "The ITS folks came over and said 'You know, these are basically Ethernet connections -- shouldn't we use them for more than just 36 bits of traffic off of signal controllers?'

"Our response was, 'Absolutely. How soon can we start?' "

The start was linking satellite fire and police stations via a wireless wide-area network, using the 5.3GHz and 5.8GHz bands with radio transceivers atop lampposts and traffic-light poles. Using existing infrastructure, the city was able to save money and piggyback on top of the Operation Green Light traffic-control system. Phase 1, covering the more populous eastern part of the city, was launched in September 2004 and completed last fall with 16 pole-mounted radio beacons.

More recently the city has deployed licensed 4.9GHz connections over Alvarion's BreezeAccess 4900 equipment, which the company said last week is now commercially available. Comprising desktop PCs in public safety locations, plus city sites like the recently constructed Lenexa Conference Center and the famous Legler Barn (the town's historical museum), the 4.9GHz network provides backhaul at speeds of 18-Mbit/s throughput in real-world conditions.

City vehicles using tablet computers get 900MHz connections ranging from 1.2 to 1.8 Mbit/s. The hardware also features Alvarion's "make before break" capability, an intelligent roaming algorithm that allows the mobile radio to make an on-the-fly judgment about which access point to connect to next. It makes the transition before the existing connection fades, similar to the handoff of a cellular call. The RF equipment will roll out to police and fire vehicles once the issue of potential dead zones has been resolved.

Alvarion VP of marketing Carlton O'Neal has observed a bit of a snowball effect with municipal wireless installations like these. "The city needs a wireless broadband network to carry out its operations, and the first step might be traffic monitoring. Then you add mobility over 900 MHz, and another department asks, 'Can we use that network too?' and of course the answer is yes.

"Very quickly you go from doing your own operations to being a type of carrier."

The price, negotiated via Alvarion's contract with the Regional Council, was about $1,300 per mobile subscriber unit, says Lawrence. So far he's quite happy with the choice of a single-vendor solution: "In the pre WiMax arena, you'll find that most end-users are going with one vendor and sticking with them."

Once vendor gear reaches full WiMax compatibility, and "a truly interoperable environment" emerges, he adds, users will enjoy much more flexibility in mixing and matching gear and software from multiple vendors.

The wireless network overlays an extensive fiber-optic grid laid down beginning in the early 1990s, which itself is due for significant upgrades.

One pleasant surprise has been the reach of the mobile broadband hubs. The assumption going in, says Lawrence, was that each base station would cover a circle 3,500 feet in diameter. But with eastern Kansas's flat topography, the distance turned out to be almost two miles. The 4.9MHz band, says Alvarion business development director Jasper Bruinzeel, gives the city a powerful backbone for its critical public-safety communications.

"What 4.9 adds," comments Bruinzeel, "is this licensed piece of point-to-multipoint spectrum to really solidify these networks, and make them carrier class not only from an equipment standpoint but also a spectrum standpoint."

The main lesson of Lenexa's wireless deployment? Think big.

"For most ITS people, the technology they're involved with and work with is 15 to 20 or even 30 years old," Lawrence explains. "We need to get this concept through of, whoa, you need to be thinking not just of ITS in any deployment, but how can this benefit the entire city? To get out of the silos and look at needs across the board.

"You may need to invest 20 to 30 percent more than solely for ITS stuff, but the benefits will be 200 to 300 or 400 percent."

— Richard Martin, Senior Editor, Unstrung

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