Intel's Centrino

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Authors: Ravi Madapati,
Faculty Member,
ICMR (IBS Center for Management Research).

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Wireless Computing

"Wires have been the natural enemy of computing. The wiring task is hopelessly manual. The spread of computing is limited by manual labor."

Andy Grove⁴ Chairman, Intel

Guglielmo Marconi had invented packet-based wireless communication more than 100 years ago. The technology remained little used until the Titanic sank. The disaster drew public attention to the potential of wireless communication as a safety measure. During World War II, the US Army developed an encrypted radio data transmission technology for communicating sensitive data among the Allies.

In 1971, researchers at the University of Hawaii created what was generally accepted as the first WLAN. This system connected seven computers across four of the islands⁵ using packet-based radio communications. WLAN consisted of access points placed in strategic locations and installed in client machines. The access points transmitted the radio frequency or infrared signal that the client machines detected and used to send data back and forth across the WLAN. Most Local Area Networks (LAN) positioned access points so that users did not experience a drop in service as they crossed from one range into another.

For instance, if a group needed to take laptops from their offices to a conference room for a meeting, they remained logged in. If users wandered out of the network, administrators established a rule such that they had to log back into the network after a certain amount of time lapsed.

Any client machine within the range of the access point could be on the network, as long as it had the appropriate permissions and settings. Typically, at least one access point was plugged into a wired LAN to connect to servers, printers, and other peripherals. However, access points with powerful directional antennas had sufficient range to transmit to each other, even in rough terrain and weather.

Mileage varied when it came to exactly how wide a range WLAN could handle. A number of factors reduced a WLAN's territory, including obstructions in the line of sight between antennae or access points and devices, whether the antennae had amplifiers and how strong they were, and inclement weather. Many companies experimented with extending their WLAN to houses 20 miles away from the office.

From a business perspective, deploying a WLAN significantly reduced the cost of running and maintaining cables, rewiring offices when employees moved, and extending the network to unwired locations. Administrators could add new clients without spending much time on configuration. Users could work on the devices of their choice without asking their IT department to set them up each time. A WLAN allowed employees to move easily from one office location to another. It allowed easy access to the network during meetings without anyone having to change settings on laptops or handhelds. The WLAN essentially functioned as an extension of the wired LAN.

But bandwidth was a key issue for WLANs. A WLAN created a lot more "overhead" with each transaction than WLANs did. Each packet of code passing through the line on a wired LAN carried a little bit of additional routing and addressing information, resulting in reduced throughput. So an 11 Mbps Ethernet network had a real speed of about 10 Mbps-not a significant difference for a user. But in a WLAN, that necessary routing and addressing information created about 35% overhead, resulting in only 8 usable Mbps out of the advertised 11 Mbps.

Another concern with WLAN was that the user had to be within range of an access point, to query the database or upload the new meter data. The software designer had a couple of options. He could force the user to input a command to upload the data to the database once the handheld device moved within range. Or the application might automate the upload any time the device re attached to the network.

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4] NET News.com, March 2003.
5] Hawaii is one of the many islands, together called the Islands of Aloha.