by Christopher Lindquist

Mobile Mesh Network Connects to Police

Sep 01, 20053 mins

The tiny California town of Ripon (population 13,000) sits amid acres of almond orchards in the San Joaquin Valley, about an hour’s drive from the state capital of Sacramento and a couple of hours from Yosemite National Park. It’s peaceful, growing rapidly—and an early test bed for an advanced, high-tech mesh network.

In a mesh, every device can be both a receiver and a transmitter, with each new node increasing the size, range and reliability of the network. Mesh gear tends to cost more than alternatives such as equipment based on the more common 802.11 wireless network standard, but if you need a network that can move with you or expand and contract quickly as your needs warrant (the military was an early adopter of the technology), mesh can be worth the expense.

Ripon’s introduction to mesh started with a letter delivered in 2003 from AT&T to Police Chief Richard Bull’s department. In the letter, the telecom provider announced that it was dropping support for the CDPD (cellular digital packet data) standard in favor of the newer, faster GPRS (general packet radio service) standard, effectively wiping out the town’s investment in CDPD equipment. Bull wasn’t happy and told the city council, “We don’t want to be at the mercy of a cellular phone company” for the town’s critical mobile data needs.

Instead, Bull suggested, the city ought to build its own network. After two years of looking at options, the town chose a mesh network system using equipment built by Motorola and installed by Lockheed Martin. Bull says that only a few other towns in the United States have begun experimenting with mesh for public safety systems.

The network, which the town began deploying in June, will consist of mesh devices—network transceivers to which laptops, cameras and other devices can be attached—that automatically connect to each other as they move within range. Patrol cars will have mesh modems installed, allowing officers to retrieve maps, criminal records and other data, even while traveling at high speed to a crime scene. They’ll also be able to tap into mesh-connected digital cameras that will be installed in a number of public areas, including a local sports complex, to monitor public events.

Local businesses are also joining the mesh project. Banks will be able to link their security cameras to a system that will provide police with pictures when an alarm is pulled, allowing officers to see what’s happening even as they’re on their way to investigate. And commercial developers are being required to integrate mesh transceivers into new construction, thus helping guarantee a robust network throughout the town.

Bull says that by programming the cameras to send images only after an alarm is triggered, the police will be able to assuage concerns about privacy. He adds that the mesh network’s proprietary wireless protocol makes it less likely to be hacked than, say, something based on 802.11. But he says the mesh backbone is the network’s only proprietary piece. Any IP-based device, from cameras to PDAs to laptop computers, can attach quickly to a mesh transceiver and work over the network. The network will also be available for other Ripon municipal groups.

The network is expected to be deployed and operating by the beginning of September. Bull expects the network will ultimately help Ripon do more with less. “We’re all strapped for resources,” he says. “If you can’t hire more officers, give yourselves more eyes out there.”