Military Mesh

Unique mesh networking system gives city cops more eyes and ears.

by / September 30, 2005
With a unique wireless mesh networking system, the 24 officers of the Ripon, Calif., Police Department will literally watch each other's backs from anywhere in the city.

The mesh network, linked to more than 50 video cameras placed strategically around the 16,000-resident, 8-square-mile city and in all police cars, allows Chief of Police Richard Bull to monitor officers, watch a site from the office or a vehicle, and lets officers watch each other.

"I can sit here in the office, and if I want to see what an officer is doing on a traffic stop, I can call up his camera and see what's going on with the unit," Bull said.

Cameras were placed at all city parks, three truck stops and downtown commercial areas.

"Thousands of vehicles come off the freeway that hit our food establishments, service stations and truck stops," Bull said. "Because it's a transient population, we see a lot who aren't the best individuals."

The total package will cost the city approximately $554,000, and the city granted Bull a reserve account of 5 percent of that for unforeseen expenses. The initial installation, about 90 percent complete in August, will get the police department operating on the system, put GIS mapping in place and equip some fire trucks with radios. Eventually all fire trucks will be on the network.

Getting the police set up means equipping all cars with cameras and modems to connect to the system, which officers will use to request data from different city, county, state and federal crime databases.

The network, sometimes called Mesh Enabled Architecture (MEA), is a military communications radio technology that evolved from research at the Defense Advanced Research Projects Agency.

The Ripon installation combines Motorola radios and modems, Sony cameras and Trango radios. Fifteen backhaul Trango connections were deployed across the city to ensure overall performance, reliability and future scalability of the network. The Ripon Public Works Department is doing the physical installation under Lockheed Martin's instruction.

Motorola has about a dozen similar citywide systems and about 100 trials around the country. The largest implementation is in Garland, Texas, the 10th largest city in the state, which comprises 63 square miles. Dan Gregory, product manager of Lockheed Martin's Business and Client Services, said an MEA network could be even larger. "As big as you want to go."

Cocoa Beach, Fla., purchased a system for its police department, which uses it to nab traffic violators. A camera is placed atop a speed trailer -- a sign flashing the speed of passing cars -- along with a modem. This allows cops to see which cars are going too fast from a hidden location. The city found other uses, including a mesh-enabled irrigation system at the municipal golf course.

Unique Application
What's distinctive about Ripon's MEA network is that it runs on a Quad-Division Multiple Access (QDMA) radio protocol platform, rather than the more common 802.11 Wi-Fi platform. The mesh system is a series of nodes, or intelligent access points, located throughout the city that transmit video feeds and communications through the radios and cameras.

There are also 51 modems that allow connectivity to the network through a regular Ethernet port, allowing multiple devices to easily connect to the network.

Ripon's mesh network relies on 15 nodes that serve as the gateway between the wired and wireless world, said Rick Rotondo, marketing director of Motorola's Mesh Networks Products Group.

"Those are typically put on buildings or water towers, but they require some sort of backhaul -- fiber, copper, something," he said, adding that there are 28 wireless routers on streetlights, light poles, traffic signals -- any place where there's power. "[Ripon] is running a computer-aided dispatch system over the network, allowing access to criminal databases and video feeds."

The difference between 802.11 wireless and the MEA or QDMA broadband, Rotondo said, is that 802.11 was intended for indoor use and works well in that setting. He said 802.11 was designed to provide a cost-effective alternative to LAN cable between a wall and a user's computer.

"802.11 has very little immunity from either self-induced or externally generated interference," Rotondo said. "These and other trade-offs were made to reduce the cost of 802.11."

QDMA broadband radio platforms were designed originally for the military and specifically for use in a wide area. The maximum range for 802.11 is about 300 feet for line-of-sight transmissions between nodes, compared to about a mile for QDMA radios.

"[QDMA] was designed to provide reliable communications under the most demanding battlefield conditions," Rotondo said, adding that QDMA radios benefit from having high-performance capabilities such as multi-tap rake receivers -- commonly found in cell phones -- and real-time equalization algorithms that compensate for the varying environments in which the radios might be used. These two features help clean up the radio signals from outside interferences.

Another benefit of the QDMA radio is the built-in position location capability -- called geo-location -- unavailable with standard 802.11. Ripon will use the feature to identify the locations of officers and fire personnel when necessary.

It works like radar, Rotondo said. If an incident commander wants to know where a certain first responder is, he will send a query to that responder's radio, which will bounce back an answer.

"Your radio will send out a ping with a time stamp on it down to the nanosecond," he said. "The query hops between the closest nodes positioned in the area to find the specific radio, and then using triangulation, it adds up all these measurements in three dimensions."

The technology could aid firefighters in finding their colleagues within burning buildings. The location capability also helps first responders keep track of equipment, such as fire trucks and ladders, and position personnel properly, Rotondo said. "A lot of times inside a building, it's very easy for guys to get turned around. You tell them to go to the north side of the building and they'll call back and say, 'I'm in position on the north side of the building,' but more times than you would think, they're in the wrong place."

Justifying the System
Some city administration, engineering and public works vehicles will be added to the system later this year.

"If you look at the justification from an ROI standpoint, it's hard to quantify from a public safety standpoint," Rotondo said. "What's relatively easy and compelling when you look at public works is when you show how many more jobs you can complete by staying out in the field and getting work orders and maps sent over the network."

Chief Bull was the impetus behind the Ripon implementation. He started thinking about the benefits of a wireless network a couple of years ago, pitched the City Council on the idea and got the green light.

"Ripon is a small community, but the chief is extremely progressive in how he's going to use technology to make his city safer," said Lockheed Martin's Gregory. "The City Council is backing it and it's going to pay big dividends for them."

Bull performed considerable research and put out a basic RFP for a wireless network in the city. He said at the time, he was considering an 802.11-type installation until he saw a proposal by Lockheed Martin and some work by MeshNetworks, since purchased by Motorola.

"We wanted to quit relying on the cellular data on mobile computers in patrol cars," Bull explained. "Our bills are fairly big, and we want to get away from them."

Bull said the system enables transmission of mug shots and more extensive data searches than before. "One of the things we're looking at before the end of the year is putting a fingerprint unit in patrol cars, so if we don't know who a person is, we can run a fingerprint through a county or state database."
Jim McKay, Justice and Public Safety Editor Justice and Public Safety Editor