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Copyright 2000 The Financial Times Limited  
Financial Times (London)

March 30, 2000, Thursday London Edition 1


LENGTH: 233 words

HEADLINE: INSIDE TRACK: US engineers find way to keep phone callers happy WORTH WATCHING


   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 frequency 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 Email


LOAD-DATE: March 30, 2000