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Telecom's Turbocharged Next Act

2 min read

It's got to be every researcher's fantasy: have a brilliant, truly revolutionary idea and watch it ignite a firestorm of controversy and disbelief. Then sit back as you are slowly but surely proved right, hailed as a genius, and remunerated handsomely for your mental leap.

It happened to Claude Berrou and Alain Glavieux, electrical engineering professors at the Ecole Nationale Supérieure des Télécommunications de Bretagne, in Brest, France, who went from relative obscurity to the engineering equivalent of pop stardom in 10 short years for their invention of la technologie turbo code . This digital coding scheme provides error-free communications at data rates and transmitting-power efficiencies that come very close to the theoretical limit first calculated by the Albert Einstein of communications theory, Claude Shannon. Your next cellphone may very well depend on turbo codes.

As Erico Guizzo writes in "Closing In on the Perfect Code," turbo codes do a remarkable thing. They let engineers design systems that are within reach of the so-called channel capacity for a given power level at the transmitter. Turbo codes made it possible to get within an astonishing 0.5 decibel of this Shannon limit. Now improved turbo-code versions are coming out all the time.

In practice this means that Berrou and Glavieux have created a coding scheme that can double data rates for a given transmitting power or, alternatively, achieve a given communications data rate with half the transmitting energy--a tremendous gain that will make it possible to send multimedia over the noisy channels typical of cellphones. And in the satellite-TV market, turbo codes will allow broadcasters to pump more data through their existing transponders. And voilà--more digital TV channels, higher definition, interactive TV, faster Internet file downloads. There are lots of other possibilities in the wireless network and data storage arenas.

No wonder the likes of France Télécom, NTT DoCoMo, Sony, NEC, Lucent Technologies, Samsung, Ericsson, Nokia, Motorola, Qualcomm, Broadcom, and Conexant have all gotten on board the turbo train. Nobody wants to miss out on digital telecommunications' next act.

And that includes regulatory bodies like the U.S. Federal Communications Commission, which understand the impact that new technologies like turbo codes are having on thorny problems like spectrum allocation. Countless pundits have identified spectrum reform as one of the most significant opportunities facing the telecom industry.

As open-spectrum proponents Gregory Staple and Kevin Werbach describe in "The End of Spectrum Scarcity," technological advances like turbo coding and many others, combined with spectrum allocation reform, will transform today's spectrum scarcity into tomorrow's spectrum abundance. Technological developments will make it possible to use the spectrum much more efficiently, allowing many different types of devices to coexist in the same spectral space without interfering with one another's operation. New radio transmission and networking technologies will squeeze more capacity out of the same spectrum or carve out new spectral territory. Wi-Fi technology, for example, has already made its mark.

Staple and Werbach predict that the "era of future abundance will be as foreign to us as our world today would be to Marconi and Tesla, whose early spark-gap radios occupied the entire usable spectrum for each individual Morse code message." Indeed, but what a welcome new world of clear and robust communications it will be.

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