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Copyright 2000 The Financial Times Limited
Financial Times (London)
March 30, 2000, Thursday
London Edition 1
SECTION: INSIDE TRACK;
LENGTH: 233 words
HEADLINE: INSIDE TRACK: US engineers find way to keep phone callers happy WORTH WATCHING
BYLINE: By DAN BILEFSKY
Mobile phone users can look forward to the day when being cut off in
mid-sentence will no longer be a daily nuisance. Engineers at
Purdue University in the US have devised a method that could make cell phone users
100 times less likely to suffer annoying disconnections.
Cell phones depend on a series of base stations that provide service to
separate regions called cells, which are arranged in a honeycomb pattern
spanning large geographic areas.
An individual cell provides hundreds of channels, or frequencies, and each
caller occupies a single channel. As mobile phone users move across cell
boundaries, they are transferred to a new channel in the adjacent cell.
However, if all the channels in the next cell are occupied, the caller is
abruptly cut off without warning.
The Purdue technology allows two adjacent cells to share many of the same
channels, ensuring that a conversation can continue as a caller travels from
one cell to the next.
In the same manner that radio stations with the same frequencies must be
separated by long distances to avoid interference, channels of the same
cannot be used in cells that are too close together.
To solve this problem, the scheme combines two or more adjacent cells in
"meta-cells", which allow the cells to use the same channels without interference. Purdue
University (Edwin Chong): e-mail
LOAD-DATE: March 30, 2000