Mesh network comes up aces in Vegas

Downtown traffic often slows to a crawl in Las Vegas, one of the nation's fastest-growing cities. The city's public works department is considering broadband wireless communications to help relieve congestion.

'Our primary interest is being able to connect with our traffic controls,' assistant traffic engineer Jorge Cervantes said.

A six-month test of a meshed wireless network will show whether better communications can ease traffic at about 20 downtown intersections. A handful of mobile city workers also will connect wirelessly from notebook computers. Eventually the city hopes to stream video from its traffic signals and expand mobile networking.

The city is testing wireless broadband equipment from MeshNetworks Inc. of Maitland, Fla., installed by Cheetah Wireless Technologies Inc. of Las Vegas.

On a mobile mesh network, devices such as notebooks, handhelds and personal digital assistants communicate with each other by IP radio connections without going through servers or other infrastructure. Each client device becomes a mobile router, passing packets to other devices that are within range.

Ad hoc mesh networks extend their reach and grow increasingly reliable as additional devices join. Networks can be created on the fly, letting personnel from different agencies share data and applications, for example, at the scene of an emergency.

Extending the network

Las Vegas joins a number of other cities experimenting with mixtures of fixed and mobile wireless mesh networks to extend their wired networks into the field.

The city can already gather data from about 350 of 600 traffic signals, which have copper cabling links to the traffic management center. However, bandwidth constraints limit the volume of data that can be sent.

The city also has some fiber cable'five or six miles' worth'but even adding another 20 miles of fiber would 'only bring about 100 of our signals onto fiber,' Cervantes said.

So the city is trying broadband wireless as a primary connection, retaining the copper for backup.
'At this point, it seems to give us the best cost alternative,' Cervantes said.

Public works currently has about 50 workers in the field carrying notebooks equipped with cellular modem cards. Their slow transmission rates limit the links to downloading simple service requests, however. They are impractical for larger files such as diagrams.

'We'd like to give them faster access to our servers,' Cervantes said.

Several notebooks will get MeshNetworks PC Cards, which will let them piggyback on the fixed equipment at traffic signals for remote access. Because each node or user on the network becomes a router, adding more users should improve performance.

Maximum bandwidth of the MeshNetworks architecture is 2 Mbps; users have reported real-world speeds from a few hundred Kbps to 1 Mbps.

The initial test will cover only a few square miles downtown. The city has an option to expand the network to 58 square miles. If it chooses, Las Vegas also could add police and fire department workers to the network.

About the Author

William Jackson is freelance writer and the author of the CyberEye blog.

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