Motorola’s Mesh Network
Bill Howard
In a burst of static, Officer Muldoon’s request for “glazed” came across the radio as “plain.” Almost as bad, the drug runners were reported to be heading west on what sounded like “Stateline Road,” when it was really “Maitland Road.”
But that was then. Now, a new WiFi mesh-networking system from Motorola could improve communications among police, fire, and ambulance crews, and — are your tax dollars finally at work? — there might be bandwidth left over for civilians at home and in cars to connect wirelessly all around town.
As first responders (basically, anyone with a badge) need to move more data, they’re expanding from two-way radio to laptop- and PDA-based communications services. The Motorola Motomesh service piggybacks on current and emerging standards to provide a network of lamppost- and building-mounted access points. Motomesh has already been deployed experimentally in half a dozen cities. This week the company publicly announced wider deployment — in Riviera Beach, Florida, and Wake County (Raleigh), North Carolina –of what Motorola calls “a total municipal wireless communications solution.”
A side benefit of Motomesh is the potential availability of broadband access for non-government employees. And it’s also a steppingstone to car-friendly mobile communications, because traditional WiFi tends to have trouble maintaining a connection in vehicles traveling more than 30 to 40 mph.
Here’s how the system works: Access points called mesh wireless routers (MWRs), typically several per square mile, sit atop lampposts. They contain four radios, two at the 4.9-GHz frequency (which is emerging as an 802.11a alternative to 5.8 GHz) and two at 2.4 GHz, which is the frequency of 802.11b and 802.11g. Government employees get access to three of the four radios.
One radio at each frequency uses Mesh Enabled Architecture and can be used at speed. Rick Rotondo, Motorola’s director of marketing, said MEA radios have been tested both on the battlefield for durability, and at more than 200 mph by the Corvette racing team that won the 24 Hours of LeMans in 2005. Many Atheros and Broadcom chipsets that support 5.8-GHz 802.11a are also capable of running at 4.9 GHz, which is in use in Japan and as a licensed frequency in the U.S.
For every five to ten access points with no wiring other than power, there’s an intelligent access point (IAP) with a wired or sometimes point-to-point wireless Internet connection. Most higher-frequency WiFi devices in the open, unburdened by building walls, work within a range of 100 to 200 meters. But devices meeting more stringent emissions standards, including the Motomesh transceivers, can bump their power from 200 milliwatts to 3 watts in the 4.9-GHz band and cover 0.3 to 0.4 miles, typically; up to 0.7 miles, in some cases.
In theory, data rates on Motomesh can go as high as 6 Mbps, although more commonly they top out at 2 Mbps. By adding more access points with backhaul lines in high-traffic areas, Rotondo says, “You can engineer how many bits per square mile you want to float out there.” With a mesh network, data can hop from radio to radio until it reaches an access point with an Internet connection.
Somebody’s got to pay for the installation. In Florida, the bill was footed by fines, seizures, and forfeitures of the drug trade. The initial setup includes surveillance cameras in high-crime areas, although so far that’s only two cameras.
With more wired and wireless capability, expect more surveillance. According to Rotondo, in England, where security cameras are common, the average Briton winds up on one camera or another four times a day. Critics claim that although terrorists and criminals are the target, some crews are disproportionately vigilant in tracking young, good-looking females and amorous couples.
Of the four radios, police, fire, and other emergency crews get access to both the MEA 4.9-GHz radio, which can be accessed at speed, and to the 4.9-GHz 802.11a radio, which meets tight emissions specs and can run at 3 watts. More routine mobile government workers, such as public-works crews and code-enforcement teams, use the 2.4-GHz band. The second 2.4-GHz band could be used by the public, as well as by government workers using a VPN for security.
For motorists who want to communicate on the go, Rotondo says, Motorola has high hopes for a marriage of WiMax — a wide-area version of WiFi expected in the next several years — and mesh networking. The combination would allow reporting of traffic conditions and roadway hazards. But it would have stiff competition from cellular-based wide-area networking, particularly the already-available EVDO services that can be used in moving vehicles.
Copyright © 2006 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in TechnoRide.
