Subject: [NEXTEL-1] In a mesh network, adding nodes multiplies its strength

From: [email-masked]
Date: Thu, 05 Aug 2004 16:23:35 -0400

08/02/04; Vol. 23 No. 21

In a mesh network, adding nodes multiplies its strength

By William Jackson
GCN Staff

Return on investment for the ad-hoc networks is attracting the interest
of governments and citizens

Wireless mesh networking holds the possibility of letting communities
extend broadband access on the fly and on the cheap to public safety
officials, municipal employees and citizens.

But just what role the emerging technology will play still is being
worked out, said Daniel Aghion, executive director of the Wireless
Internet Institute of Boston.

“I wouldn’t call it mature, because there are few places where broad
deployment has been done,” Aghion said.

Tests and pilots are beginning to yield reliable results, however, and
the return on investment in communities where it is being deployed is
making ad-hoc networking attractive.

Wireless mesh networking is a technology developed by the Defense
Advanced Research Projects Agency for creating multihopping IP networks
in which individual nodes are wireless routers. This eliminates the need
for cellular or radio repeater systems that traditionally pass radio
signals from dumb nodes.

The networks are ad hoc because the routing nodes can be mobile and the
architecture is constantly shifting, with new routing tables being
created as nodes move in and out of range of each other.

“The more devices are added, the more reliable they are,” because more
nodes become available for routing traffic, said Michael Griffin,
assistant chief of the California Governor’s Office of Emergency
Services.

California’s Office of Emergency Services recently participated in an
interagency trial of the technology in the San Francisco Bay area.

A number of companies are commercializing the DARPA technology, using
different approaches.

PacketHop Inc. of Belmont, Calif., uses a software solution, with client
programs that can be loaded on notebook and handheld computers. The
computers can use most types of wireless network interface cards. A
network controller appliance acts as a gateway between mobile and wired
segments. This is the scheme tried out by the Golden Gate Safety Network
in the first test of the products. Users were able to use the system
with almost no training, Griffin said.

MeshNetworks Inc. of Maitland, Fla., uses its own PC Cards in mobile
computers and vehicle-mounted modems to listen for other nodes on the
network. This system has been implemented in Medford, Ore., to give
police cars, fire trucks and ambulances high-speed connections to the
city’s wired network.

Bandwidth available to the end user varies depending on protocols used
to transmit IP over radio frequencies, but practical speeds can range
from a few hundred Kbps to 1 Mbps, both upstream and down.

In this country, municipalities are among the early adopters of wireless
mesh, with a handful of systems implemented. Many more communities are
waiting to see if the technology can fulfill its promise.

Although many communities would like to be able to offer broadband
access as a utility, the first implementations are showing up in public
safety. Police and fire departments offer a closed environment where it
is easy to conduct pilots with a host of applications that can be
accessed for a quick return on the investment.

Beat goes on

San Mateo, Calif., a city of about 110,000, installed 30 fixed mesh
access points to cover a five-square-mile section of the city. Using
WiFi notebooks to access data and print reports without coming into an
office allows its 30 police officers to stay on the beat 25 percent
longer.

“That’s a huge productivity gain,” with an estimated payback time of six
or seven months, Aghion said.

Medford, Ore., spent about $200,000 on its mesh network, in addition to
a $500,000 grant from the Homeland Security Department. Technology
director Doug Townsend estimated the city would recoup its share of the
investment in about eight months with better productivity. Those savings
do not include anticipated reductions in the police department’s
cellular phone bill.

But whether and to what extent public safety networks should be shared
with other departments is a question that still needs to be worked out.

http://gcn.com/23_21/news/26796-1.html

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