Mesh networking to the rescue

Telecommunications Americas, March, 2004 by Sue O'Keefe

In the first and largest deployment of its kind, the City of Garland, Texas, is replacing its cellular-based CDPD communications system with mobile mesh networking technology. The networks will be used by the city's first responders--police, fire and medical emergency personnel--to transmit data at rates up to 1.5 Mbps in a mobile environment. The contract was awarded by the city and Lockheed Martin--the project's system integrator--to Richardson, Texas-based NexGen City.

During trials last year, units deployed in the field using two vehicles traveling more than 60 mph in opposite directions demonstrated real-time streaming video, VoIP calls and data throughput rates of up to 1.5 Mbps. The contract calls for data communications implementation initially, with voice and streaming video capabilities added later on, if required. With a population of 221,000, Garland is the 10th-largest city in Texas.

"Being able to send and receive data reliably and up to 50 times faster than before, while in transit, will have an enormous impact on how our first responders manage a crisis and solve our city's daily public safety challenges," said Darrell McClanahan, Garland's telecom manager.

NexGen City's NexNet product is based on ASICs from Maitland, Fla.-based MeshNetworks. While much industry hubbub surrounds Wi-Fi implementations, mesh networking is the wave of the future, declares Rick Rotondo, vice president of technical marketing for MeshNetworks. "One of the biggest advantages of mesh technology over Wi-Fi is that Wi-Fi can't be mobile; the physical layer of Wi-Fi technology does not support mobility," Rotondo says.

NexGen's Garland network is based on a micro-cellular architecture in which router functionality is placed in every network component, creating a self-forming and self-healing network with peer-to-peer networking capabilities. NexGen City's approach embeds a wireless router in every device so that each unit can extend the network, determine optimum paths for data transmission, and provide additional paths for connectivity. This dynamic routing capability enables devices to hand off communications seamlessly even while used in vehicles traveling at high speeds.

In the Garland implementation, NexGen's NexRouter and NexAccess products are deployed on existing infrastructures, such as buildings, streetlights and traffic lights in a grid, or mesh fashion, forming a tight network with no single point of failure. User devices NexPaq (scheduled for production in mid-year) and NexCard act as repeaters, so that the more devices that are available, the more signal paths that are created, and the more fault-tolerant the network becomes. The system also includes a geo-location application that does not require satellite-based GPS receivers. Each fixed device supports latitude, longitude and elevation attributes, while triangulation calculations produce the same attributes for each mobile device registered on the network.

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