Wireless gets connected
- By Brad Grimes
- Jan 23, 2004
Cities eye mesh networks for market communications
"The promise of mesh networking is to give the technology to first responders, who go into buildings where there is poor or no coverage." ? Gary Grube, chief technology officer of Motorola's government sector.
There is a common misconception that wireless networks are, well, wireless. In fact, wireless networks are very wired. All those access points that transmit radio signals to and from mobile workers are connected to a wired network using -- you guessed it -- wires. And those fixed backhauls, as they're called, can be a significant hindrance to wireless network adoption.
"When you're building a wireless hot zone and covering a campus or metro area, these client-server, single-access point cells that backhaul everything over the Internet can be costly to deploy," said Ian McPherson, principal analyst at the Wireless Data Research Group in San Mateo, Calif. Stringing wires to dozens of access points is no small task, he said.
Bert Williams, vice president of marketing for Tropos Networks Inc., a mesh networking company in San Mateo, Calif., estimated that 90 percent of the cost of a conventional WiFi network comes from the wired backhaul infrastructure.
Consequently, getting rid of wired backhauls is seen as a big step toward increasing deployment of wireless networks at government agencies.
Enter mesh networking, a technology that allows wireless access points to transmit data through one another, instead of through wired backhauls, as information is relayed to the main network.
"With a mesh network, you can reduce capital expenditures by 80 percent," Williams said.
What's more, wireless mesh networks offer other potential benefits, said officials from several wireless companies. They can give organizations better coverage for their money, so more workers can use the network over a wider area.
They're also more reliable than typical wireless networks, because they can re-route information if an access point malfunctions. Certain mesh networking technologies enable communications in buildings or environments where interference or physical impediments make wireless communications impossible.
Companies such as Tropos, MeshNetworks Inc. and Ember Corp. are applying the mesh-network concept to wireless networks for public safety, emergency response and other applications. Williams and other executives tagged the market for mesh networks in the public safety sector at more than $1 billion.
FROM DARPA TO FIRST RESPONDERS
Mesh networking has its roots in the Defense Advanced Research Projects Agency, where researchers developed self-organizing, wireless, peer-to-peer networks for the battlefield. In a wireless mesh network, access points and wireless devices organize themselves into an ad hoc network, communicating with each other to determine the fastest way to send data to the wired network. The network still needs a backhaul, but not to every access point.
Wireless mesh networks are much like the Internet itself, where data hops from router to router looking for the shortest available path to the requested server. Mesh companies develop routing protocols that help wireless access points and routers do the same thing. These protocols take into account network traffic, throughput, signal-to-noise ratios and various forms of interference, such as passing trucks and cordless phones.
Whereas the Defense Department was interested in mesh networking to get around radar jamming devices and to ensure reliable communications, today's users look at the technology as a way to build wireless networks for public safety agencies.
In September, Tropos installed a wireless mesh network based on 802.11b WiFi standards for the San Mateo, Calif., Police Department. The network covered an outdoor area roughly two square miles in the city's downtown section. Officers carry WiFi-enabled notebooks in their cars, and as long as they're within range of the wireless hot zone, they can access networked resources, such as a countywide intranet that connects to the Amber Alert system and other databases.
San Mateo Police Chief Susan Manheimer said the Tropos network helps officers solve crimes more quickly.
The San Mateo network comprises nearly 40 access points, which is more than usual, Williams said. Because the police department didn't want to outfit squad cars with external antennae, Tropos had to install extra access points to provide strong signals throughout the hot zone. Most of the points are mounted on street lights, where they draw the power they need.
Williams said that Tropos uses multiple layers of security and authentication to protect its mesh networks, and recommends that agencies use virtual private networking to establish secure communications. The San Mateo Police Department uses VPN technology from Seattle-based NetMotion Wireless Inc.
MeshNetworks of Maitland, Fla., takes a slightly different approach to wireless mesh networking. The basic peer-to-peer topology is the same, but whereas Tropos bases its solutions on WiFi standards, MeshNetworks uses a proprietary technology that pulls end user devices into the network. Instead of only routing data from access point to access point, a MeshNetworks solution turns wireless-enabled PDAs, notebooks or other devices into network nodes.
"In our ad hoc network, the devices are the network," said Peter Stanforth, chief technology officer at MeshNetworks.
MeshNetworks' technology, which is sold through systems integrators and value-added resellers, is aimed at the public safety market, especially for first response. For instance, when firefighters enter a building, their wireless radios can become a self-contained network that relays data to one another and eventually out of the building.
NexGen City LP is building a wireless solution for the city of Garland, Texas, based on MeshNetworks technology. Working with Bethesda, Md.-based Lockheed Martin Corp., NexGen City plans to deploy 400 fixed access points and 200 mesh-enabled devices to create a wireless network covering 60 square miles.
Richard Dwelle, president of Richardson, Texas-based NexGen City, said he expects Garland's network to pay for itself in just one year.
Schaumburg, Ill.-based Motorola Inc. is particularly interested in the MeshNetworks approach as a way to protect emergency response teams.
"The promise of mesh networking is to give the technology to first responders, who go into buildings where there is poor or no coverage," said Gary Grube, chief technology officer of Motorola's government sector.
With enough bandwidth, Grube said public safety officials could use mesh networking to track firefighters and emergency workers as they move through a building. Gauging location is possible because each responder's wireless device acts as a node on the network.
"That information can be routed wirelessly to the captain on the street, who has a map of the building on his notebook computer," Grube said.
THE INTEGRATOR MARKET
No matter which flavor of mesh networking agencies adopt, mesh companies said systems integrators are critical to their deployment.
"We look to work with systems integrators for installation and companion products," Williams said. "We need to make sure our products are integrated with the agency's existing network, and most public safety groups require additional solutions, such as VPNs."
Stanforth said MeshNetworks partners with integrators such as Annapolis, Md.-based Arinc Inc. and Armonk, N.Y.-based IBM Global Services.
Although experts aren't sure when wireless networking will become widespread, they agree that mesh networking will play an important role in adoption by the government.
"The mesh architecture is here to stay," Grube said. "Over time, it will help people fine-tune the economics of wireless coverage."
Staff Writer Brad Grimes can be reached at firstname.lastname@example.org.