December 10, 2007, 11:22 AM — Denver International Airport is betting that travelers will like getting something
for free, and so far it looks like a good bet.
The airport, one of the busiest in the U.S., last month switched its public
Wi-Fi offering from paid to advertising-supported. Within a week, and with no
public notice of the change, Wi-Fi use grew tenfold, said Jim Winston, director
of telecommunications for the airport. He expects the network to get even busier.
DIA is a large-scale case study of free Wi-Fi in airports. About 50 million
passengers pass through the airport every year, with as many as 165,000 per
day during busy times of the year, airport spokesman Jeff Green said. Now that
Wi-Fi is free, there are 7,000 to 8,000 connections to the network per day,
according to Winston. To link all those free users with the Internet, the airport
at first bumped up its "backhaul" to 5M bps (bits per second) but
later found that wasn't enough. It now has a 10M bps connection just for the
Wi-Fi users.
The change was part of a complete revamping of the Wi-Fi service, which DIA
first offered in 2002. For the first five years, the airport owned its own network
but turned to AT&T to operate and maintain it in return for a concession
fee. AT&T charged users on a variety of models, including one that cost
US$7.95 per day. Now the airport has taken over the service and installed a
whole new network with the latest technology.
Denver may be the first airport in the U.S. to deploy a public Wi-Fi network
with IEEE 802.11n Draft 2.0 capability. The new technology, which the Wi-Fi
Alliance is certifying for interoperability because the final 11n standard has
been delayed, is designed for higher speed and longer range than previous versions.
DIA's network also supports earlier versions of Wi-Fi.
The airport turned to Meru Networks for its infrastructure, partly for ease
of management, Winston said. AT&T fixed and upgraded access points and bore
that cost itself. As the carrier left the picture, DIA knew it would have to
handle firmware upgrades and other changes to the approximately 60 access points
in the 53-square-mile airport.
Even moving to the free model, "we would still have to visit each one
of them," Winston said. Meru's management software lets administrators
modify each access point remotely, he said.
DIA also liked the company's "single-channel" architecture. It runs
all access points on the same Wi-Fi channel, treating interference as overlapping
signals and automatically connecting users to another nearby access point if
one gets overloaded. If that channel reaches its capacity limit, another one
can be used. The airport has already seen 25 clients using one access point.
Winston believes the system could handle as many as 45 at a time.
Public Wi-Fi providers such as DIA don't need to roll out Draft 11n access
points yet, Gartner wireless analyst Ken Dulaney said. Few notebook PCs are
even equipped with the technology today, and the bottleneck in most such setups
is the shared backhaul to the Internet rather than the speed of the wireless
LAN itself, he said.
However, one benefit of the 11n capability doesn't depend on legitimate customers demanding high speed, according to Meru. With its built-in 11n, Meru's network can easily detect unauthorized 11n access points in the area that could pose a security threat, said Rachna Ahlawat, vice president of strategic marketing at Meru. The alternative is a separate device just for detecting rogue networks, a significant added cost, she said.
Using a Wi-Fi network without 11n, administrators could detect a rogue hotspot,
though they couldn't immediately tell it was an 11n system, Gartner's Dulaney
said. He acknowledged the built-in 11n detection would make the IT department's
security job easier.
Ease of management is important for the network because it still needs to make
a return on its wireless offering even though travelers aren't paying for it
directly, Winston said. DIA has construction bonds to pay off. So FreeFi Networks,
a Wi-Fi advertising company, sells video ads that appear right before the user
starts using the Internet and a persistent ad bar at the top of the computer
screen, he said.
If the system keeps delivering on its promise, DIA will probably roll it out
on another network it operates for airlines and concessionaires, which pay a
monthly fee for a variety of data and voice services, Winston said.
