SciFri 7.8.05: WiFi in a nutshell

Today, the majority of new laptops have built-in wireless access cards. Apple was the first computer company to make them a standard, installing them in their iBooks.

Wireless technology is fast, convenient, but not as secure as wired.

By Deane Morrison

Published on July 8, 2005

The city of Minneapolis is taking proposals to build a citywide wireless Internet service. Known as WiFi (wireless fidelity), the technology is already well known to many U of M faculty, staff, and students. WiFi might also stand for wildfire, given the way it's spread over the last seven years or so since its debut.

The basis of WiFi is simple. A laptop computer outfitted with a small radio antenna "talks" to a radio antenna stationed nearby in a cyber cafe, Coffman Union, the St. Paul Student Center-anywhere access is provided. WiFi-capable computers have an electronic "signature" embedded in all communications between computer and antenna, which allows the antenna to keep signals from different computers straight. The antenna passes signals along to a wire connected to the Internet. Service is broadband, meaning it provides high-speed communications.

Antennas range in size from about six inches up to about five feet. The bigger the antenna, the larger the territory it can cover; small antennas may pick up signals within 50 feet, while the largest can detect signals several hundred feet away. Where antennas are placed depends on not only their size but on their surroundings. For example, a cyber cafe that's one big room may need only one, but a large building with multiple rooms may have an antenna in each room if signals don't pass through walls easily.

The broadband access via WiFi can typically support 5 to 10 users, although bigger antennas may allow for 50 users. But the flow of information is shared; therefore, if a few people are watching movies or otherwise demanding huge numbers of bytes per second, another user may experience difficulty.

Today, the majority of new laptops have built-in wireless access cards. Apple was the first computer company to make them a standard, installing them in their iBooks. But while laptop owners everywhere love WiFi, computer security professionals are more cautious about expanding the technology without proper controls. Wireless communication, whether by WiFi or cell phones, is less secure than the wired route, as Princess Diana found out when her private calls were picked up by a third party. When the College of Cardinals was meeting in Rome recently to choose a new pope, they operated under a ban on cell phones and personal data organizers, among other items, laid down by the late Pope John Paul II. Had any cardinals carried such devices, a hacker could possibly have penetrated a device, activated its microphone and listened in on sensitive conversations. Apparently, the ban and the extra-tight security surrounding the cardinals carried the day.

As Minneapolis gets into the WiFi zone, it will be part of the continuing development of the technology and who provides the service. (see MPR story). WiFi in the cities of Chaska and Moorhead is city-owned and operated, and Philadelphia's service is provided by a nonprofit), but Minneapolis is looking for a private contractor to provide service. One contractor means a monopoly, and whether WiFi will bring the same headaches as cable TV service remains to be seen.

Currently, engineers are working hard to make WiFi available over longer distances. Cell phones are ahead of WiFi in this respect; phones don't have to be as close to towers as WiFi must be to its antennas. On the other hand, cell phones can't handle nearly the volume of data that WiFi can; they're just starting to ramp up their transfer speeds. For example, although camera phones can send video, the pictures are still very small and low quality. WiMAX, a new technology that hasn't yet been implemented, will expand the range of WiFi antennas.

To find campus locations that are wired for WiFi, see the WiFi map.