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Shannon’s Limit: Little known, huge impact

Thursday, 08/11/2016

Great scientific theories just never go away. In whatever level of education, research or product development, names that include Einstein, Plank and Heisenberg resonate today just as strongly as they did when their theories were exposed over the last 100 years.

But there’s one exception – Claude Shannon. Here’s a name that is seldom mentioned but belongs to one of the most brilliant and important theories to have impacted communications science over the past 60 years – Shannon’s Limit.

Basically, Shannon showed that any communications channel — a telephone line, a radio band, a fiber-optic cable — could be characterized by two factors: bandwidth and noise. Bandwidth is the range of electronic, optical or electromagnetic frequencies that can be used to transmit a signal; noise is anything that can disturb that signal.

Given a channel with particular bandwidth and noise characteristics, Shannon showed how to calculate the maximum rate at which data can be sent over it with zero error. He called that rate ‘channel capacity’, but today, it’s just as often called the Shannon limit.

Published in a 1948 paper, Shannon’s work created the field of information theory — and set its research agenda for the next 50 years. In the early days of PCs during the ‘80s, Shannon’s limit was working overtime, with communications scientists trying to improve transmission over telephone modems.

Since then, the low cost of high bandwidth connectivity has addressed Shannon’s Limit simply by adding redundancy. Most recently, though, businesses are realising the poor business practice of throwing bandwidth at the problem and are now returning to prioritisation policies and improved quality of service as a more cost effective approach. Noise (particularly latency) is back on the agenda as enemy number one and Shannon’s work is again the centre of attention.

So hats off to Claude Shannon, without whom most of us working in business comms would be out of a job today.

See how Genius deals with noise from network latency

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