Now imagine the average mesh network as a swarm of bees, and take that same stone -- heck, take 100 stones -- and hurl them into the buzzing mass. You may take out a few bees -- perhaps many -- but the swarm will remain intact.
In real life, vital cell towers are susceptible to attacks and natural disasters, with long-term service interruption a near inevitability in either case.
To avoid such a situation, one Texas town replaced its existing communications networks with mesh network technology, which relies on a distributed network of devices rather than a central orchestrating device. The new mesh system provides the city with a powerful broadband network that supports high-speed data, streaming video, voice messaging and precision geo-location.
When Disaster Strikes
In addition to cell towers being ruined in a disaster, cellular service can also be overwhelmed -- problems can arise from millions of music-loving TV-viewers using cell phones to cast electronic ballots for the latest American Idol. In a more ominous scenario, overwhelmed cellular communication systems can -- and have -- imploded into uselessness during large-scale emergencies and disasters like 9/11.
It may be impractical, imprudent and perhaps even downright foolish for first responders to rely on cellular technology for data -- let alone voice and video -- transmission needs during an emergency situation.
Enter DARPA. The Defense Advanced Research Projects Agency is the government organization perhaps best known for inventing the Internet. In 1997, the agency began work to ensure better, more powerful, secure and dependable battlefield communications.
DARPA engineers created a network that requires no infrastructure, but rather exists via user-devices, such as handheld computers and mobile phones, which act as transmitters. In theory, these "mesh networks" could instantly form between as few as two users via nodes embedded in system devices, which act as relay points for any other node. This allows signals to "hop" from one device to the next instead of being routed through a central device.
The technology worked, but DARPA's heavy communications equipment limited its practicality. So the military awarded a private company, ITT Industries, a contract to improve the technology's user-friendliness.
In January 2002, MeshNetworks Inc. was formed to commercialize the new mesh technology for the nonmilitary sector. The company now holds the exclusive license, patents, software and design that resulted from the DARPA and ITT Industries research, according to Rick Rotondo, MeshNetworks' vice president of technical marketing.
MeshNetworks reduced the technology to a single chip, which Rotondo said took more than two years and $20 million. But the investment seems to be paying off as the first citywide deployment of its technology nears completion.
Mesh Meets Needs
Garland, Texas -- a Dallas-area suburb with a population of more than 200,000 -- has almost finished deploying a mesh network across its nearly 60 square miles. Like many jurisdictions across the country, Garland IT professionals scrambled to replace their cellular digital packet data (CDPD) system. Law enforcement relies on this specification, which supports wireless Internet access and other public packet-switched networks -- but the FCC is phasing it out this year.
Along with their CDPD system, Garland officials were also having coverage problems with an aging simulcast radio system. Darrell McClanahan, Garland's telecommunications manager, wanted a solution to resolve both wireless problems.
McClanahan said he liked the idea of mesh networks, but had to be sure the mesh network could keep up with city employees.
"One of my concerns was in combining both voice and data -- would I provide throughput at highway speeds?" he said.
Richard Dwelle, president of NexGen City (NGC), currently the only OEM using MeshNetworks' concepts, agreed to build a proof of concept for the city.
"I provided a section of interstate highway about six miles long and asked them [NGC] to supply some equipment," explained McClanahan. "Lo and behold it worked."
In a mesh network, signals hop between nodes to find the best routes, so there is no single point of failure. If one node, or several nodes, suddenly becomes unavailable, the network automatically reroutes signals through other fixed and/or mobile nodes.
In theory, with enough users, a mesh network wouldn't need fixed wireless routers. In real-world practice, however, wireless routers that ensure connectivity over large areas can be attached to a jurisdiction's pre-existing infrastructure, such as streetlights and buildings. In addition, intelligent access points (IAPs) -- also deployed on existing structures -- act as bridges between the mesh network and the wired world.
"I can drive at 60 mph and keep my link," he explained. "That allows you to move seamlessly from communicating peer-to-peer into the network infrastructure and back again."
Garland will utilize NGC's NexCard in the city's nearly 100 in-vehicle Panasonic Tough Books to make them part of the mesh network. The city will later act as a testing ground for NGC's handheld NexPaq ruggedized personal communicator, which is currently in development.
NGC's service department will maintain the network, which supports delivery of high-speed data, video and voice messaging with bursts of up to 6 Mbps. End-to-end Internet protocol (IP) is also supported, so any IP device also works seamlessly in the network, according to Rotondo.
Another plus for law enforcement officials is that instead of becoming sluggish or completely inoperable when bombarded with an unusually high network traffic, the capacity and efficiency of a mesh network increases as users are added.
"A mesh network is weakest when there is only one user," explained Rotondo. "A cellular network is best when only one person is using it. As users are added, a mesh network only gets better, but cellular networks get worse."
Mesh networks also are inherently easy to secure, said Rotondo, because packets of information don't necessarily hop directly from point A to point B -- they take different routes through various user devices and wireless routers. Because they are an all-IP system, mesh networks support security measures like firewalls and end-to-end encryption through virtual private networks.
Mesh Supports Many Uses
Garland's mesh network also includes built-in geo-location that doesn't rely on GPS satellites -- especially handy when first responders or others are deployed inside dense, cellular-unfriendly buildings. MeshNetworks is perfecting its "breadcrumb routers" for use in such conditions.
"Breadcrumb routers are little battery-operated wireless routers first responders place or drop as they go through a building," explained Rotondo. "They form a reference network first responders can communicate through and be tracked from."
Beyond the instant incident communication enabled when several mesh users arrive at a major emergency, breadcrumb routers provide geographic location information and better communications between those inside and those outside a structure.
The routers -- only the size of couple decks of cards -- can be packed on a "Batmanlike utility belt," scattered through a structure, then retrieved when an incident is resolved, Rotondo said.
Add-ons like temperature sensors and smoke detectors can be attached to the tiny routers via serial ports, making them even more valuable to firefighters and others attempting to mitigate large- and small-scale emergencies.
Garland's mesh network was built on a $4 million budget, which was originally earmarked for a system to replace Garland's disappearing CDPD system.
In the Zone
The network solved zoning problems McClanahan experienced when trying to get the city to approve zoning variances for more cell towers, which were necessary to improve the simulcast radio system the city once considered necessary.
"Nobody wants a 200-foot tower in their back yard," said McClanahan. "And you can't blame them."
The Garland City Council finally allowed a planned water tower to double as a cell tower. McClanahan quickly agreed, but now, even as the mesh network nears completion, ground has not yet been broken for the new water tower.
The mesh deployment will eventually include nearly 400 structure-mounted routers and IAPs. The permanent, shoe box-sized technology is being scattered throughout Garland on city-owned light poles, traffic signals, power poles and buildings with no zoning issues, said McClanahan.
Deploying dozens of small IAPs and wireless routers on existing infrastructure is much less expensive than building even one cell tower.
Eventually McClanahan said he hopes to bring other city departments into the mesh network.
"There are a lot of possible applications," he said. "The water department has approached me, customer service has approached me, even meter readers."
Dwelle wasn't surprised.
"I think once it hits, it hits big and just takes off," said Dwelle. "It solves so many inherent communications network flaws that public safety -- or any municipality -- deals with."
Medford's Mesh
In Medford, Ore., the story is much the same. Seeking increased interoperability and high-speed data rates -- as well as mobility for law enforcement, fire and rescue, public works, and building inspectors -- city officials believe mesh networking is the answer.
The Medford project is roughly half the size of Garland's deployment. Located in southern Oregon, Medford spans 22 square miles. Approximately 100 city workers will initially utilize Medford's mesh network, which is the first deployed in the state.
But mesh technology pioneers -- such as MeshNetworks and its associates, Viasys Services and NexGen City -- are finding themselves less and less alone. Recently a handful of mesh-related companies sprung up around the world, with many projects spilling from the government realm into the private sector.
Organizations such Tropos Networks and Ember Corp. are applying mesh networking concepts to U.S. public and private sector projects. A collaborative effort between Mitsubshi and Deutsche Telekom, known as Moteran, is outfitting autos in some vehicle-dense cities in Germany with high-bandwidth mesh networking equipment to facilitate in-car entertainment systems and communications.
Even large U.S. corporations, such as Intel, Raytheon, Rockwell-Collins and Motorola, are involved in various mesh-related projects.
The explosion of interest doesn't surprise NGC's Dwelle, who admits his company didn't actively publicize their products' possibilities until they had a concrete customer in Garland.
"I would be egotistical to think there wouldn't be some pretty stiff competition that comes out of this," said Dwelle. "I hope it does because that validates that what we've done with this company and its product line is a widely accepted solution."
MeshNetworks' Rotondo agrees, but takes his enthusiasm for the mesh concept even further. He sees mesh entering homes and eliminating the mess of cables now linking home-entertainment devices and computers.
"People aren't going to keep connecting cables to everything. It's too complicated," said Rotondo. "With mesh, I could have an access point in my office, and since I have a computer that controls my home theater system, that could be mesh enabled. Signals could hop through my house or outdoors and extend the range of my wireless automatically. As I add devices, I'd actually increase the coverage and capacity of my network."
All that seems ambitious, but Rotondo is only warming up -- just as mesh networks seem to be.
