How the Inventor of DSL Altered the Course of Connectivity

When 7-year-old John Cioffi ran as much as the Bell System pavilion at the 1964-1965 World’s Fair in New York City, he couldn’t wait to see the first phone with video: the much-lauded Picturephone.

The boy had been disillusioned that cellphone calls offered solely audio. He gazed up at the Picturephone’s oval display, with its grainy, black-and-white video pictures—the end result of US $500 million in R&D by the telecommunications big—and thought, Wow…that appears horrible!

“That memory always stayed in the back of my mind,” Cioffi says. “As I went through my schooling and career, it seemed that the technology should be able to get there, and I was always curious about how we could make it happen.”

Nearly three many years later, at age 35, Cioffi developed the expertise that may in the end make doable video calls and far more together with high-speed Internet. In 1991 he constructed the first uneven digital subscriber line (DSL) modem, which shortly changed most dial-up connections. DSL meant a consumer may obtain data-heavy pictures and movies whereas concurrently shopping the Internet and speaking on the phone, all from a single cellphone line.

DSL works by separating digital voice and knowledge indicators, then changing them into analog indicators that may be despatched much more shortly and simply over wires—sometimes the copper traces already present in landline telephones. Cioffi is named the “father of DSL” not solely as a result of of his creation of the first such modem but additionally his work to commercialize and popularize the expertise.

For his DSL efforts, Cioffi obtained a U.S. National Medal of Technology and Innovation, one of 12 bestowed in October by President Biden throughout a White House ceremony. The medal, the nation’s highest award for technological achievement, acknowledges U.S. innovators whose “vision, intellect, creativity, and determination have strengthened the country’s economy and improved the quality of life,” based on the White House.

“I was awestruck and never imagined that they’d select me for this one, as there are so many [people] I can think of who’d be more deserving,” says Cioffi, an IEEE Life Fellow. “I came to learn that several [of my] former students—Dr. Krista Jacobsen, Professor Katie Wilson, and Dr. Pete Chow—were the nominators.”

The expertise led to high-speed Internet, with knowledge capacities and transmission charges that had been unimaginable with dial-up programs. What’s extra, DSL relied on the copper wires that cellphone firms insisted to Cioffi had been passé, thereby unlocking a future endlessly altered by connectivity.

Fighting for copper in a fiber-obsessed world

Cioffi arrived at engineering by means of his love of arithmetic. He had at all times been desirous about pushing the boundaries of what was doable primarily based on mathematical equations. After graduating in 1978 with a bachelor’s diploma in electrical engineering from the University of Illinois Urbana-Champaign, he started engaged on knowledge communications as a member of the technical employees at Bell Labs in Holmdel, N.J.

There he helped develop the first voice-band modem with echo canceling. It allowed high-speed voice knowledge to be despatched over a single phone circuit—which permitted simultaneous transmission of each callers’ knowledge with out both disturbing the different. It was his first style of maximizing what was doable over only one cellphone line.

His enhancements to Bell’s modems bought him observed by high management. It was the early Nineteen Eighties, and fiber-optic networks had been seen as the future in telecommunications. The firm already had digitized most of the course of for connecting calls, however last-mile connectivity was nonetheless analog: that pair of copper cellphone traces twisted collectively. To digitize that final important bit, Bell engineers had been creating the Integrated Services Digital Network, a circuit-switched phone system to ship voice, video, and different knowledge over digitized circuits.

In one assembly to debate ISDN, Cioffi listened as senior, well-known Bell scientists and engineers talked about targets equivalent to making an attempt to ship 150 kilobits of knowledge per second to allow a number of voice channels on a single line. He was befuddled by their method and questioned why video wasn’t half of the dialog.

“We knew the judges wouldn’t select a little company’s technology unless it was really a slam dunk, and it was.”

He shortly did some back-of-the-envelope calculations after which interrupted the dialogue. The system truly may deal with 10 occasions as a lot knowledge, he defined, so video calls had been doable. His boss shot him a glance to maintain quiet.

Shutting down Cioffi’s solutions grew to become a theme at Bell, he says. The firm was all in on a lower-speed ISDN, and it wasn’t desirous about his concepts for the current copper wires, which had been predicted to be historical past quickly. They stated ISDN’s successor could be fiber to each residence.

“The old way is dead. Everything will be fiber within a couple years,” Cioffi was instructed. “You need to think ‘infinite bandwidth.’ What can someone do with that?”

Cioffi says that regardless of the setbacks, he loved his work at Bell, and the firm paid the tuition for the Stanford grasp’s and Ph.D. levels he pursued throughout paid leaves.

After he earned his doctorate in 1984, the U.S. authorities was in the midst of splitting up the Bell System, so he left the firm to work for IBM in San Jose, Calif., as a analysis employees member. While there he developed expertise that elevated the capability of storage disks by about 50 %.

In 1986 Cornell approached the 30-year-old about instructing electrical engineering. Unsure if it was the proper profession transfer, Cioffi requested his Stanford advisor what to do. The advisor stated Stanford itself had a gap for an EE professor—and Cioffi accepted the job at his alma mater.

Creating the first DSL modem

At Stanford, Cioffi and his graduate college students labored on discrete multitone modulation, a method for sending digital info over wires whereas adapting indicators for effectivity. It was, he says, a needed precursor to DSL.

Cioffi says he was energized by instructing superior EE college students and being free of the fixed no’s he’d obtained in the company world. In 1987 he was given a Presidential Young Investigator Award, which offered monetary assist to assist him advance his work: $312,000 (about $870,000 as we speak) over 5 years.

By 1991, he was satisfied he and his college students had created the applied sciences wanted to construct a DSL modem. He took a go away of absence from Stanford to launch Amati Communications Corp. in Palo Alto, Calif.

John Cioffi was offered with the U.S. National Medal of Technology and Innovation by President Biden throughout a ceremony held in October at the White House. Anna Moneymaker/Getty Images

Cioffi’s present and former college students labored with him and different colleagues to construct the first DSL modem: the Amati Prelude. It was revolutionary, transmitting about 6 megabits of knowledge per second over greater than 2,700 meters of phone line: sufficient to assist a number of dwell digital TV streams at the time.

Meanwhile a quantity of massive firms had been making an attempt their very own approaches to DSL, together with two linked to Bell. In 1993 Bell Communications Research, often called Bellcore, sponsored a DSL competitors. The Amati crew entered Prelude, competing towards AT&T, Broadcom, and Bellcore itself.

Amati’s modem despatched knowledge extra shortly over better distances whereas utilizing a lot much less energy than the different entries. The competitors, based on Cioffi, “wasn’t even close,” as Amati received the gold medal.

“We knew the judges wouldn’t select a little company’s technology unless it was really a slam dunk, and it was,” Cioffi says. “The rest is history.”

Dial-up modems certainly had been historical past. DSL vastly diminished load occasions and ultimately led to video calls, streaming video, and the relaxation of the trendy Internet expertise as we all know it.

Meanwhile, constructing out fiber networks wasn’t transferring almost as shortly in the Nineties as the cellphone firms had predicted. (Decades later, the fiber buildout remains to be gradual going.)

DSL powered thousands and thousands of households worldwide for years—and although the expertise is being phased out in favor of 5G and fiber in lots of areas, it stays the solely supply of broadband web for Americans in rural communities and remains to be utilized in tons of of thousands and thousands of properties globally.

After the Bellcore contest win, Cioffi returned to instructing at Stanford whereas nonetheless collaborating in Amati, which went public in late 1995. In 1998 Texas Instruments purchased the firm for $440 million (the equal of about $854 million as we speak).

With DSL expertise confirmed, Cioffi’s pursuits turned to enhancing its efficiency. In 2003 he based Adaptive Spectrum and Signal Alignment—ASSIA, a backronym for his spouse and co-founder, Assia Cioffi—to attain the purpose.

The firm employed about 170 individuals at its peak. Over the years, it developed to largely licensing its mental property for Internet optimization strategies. Cioffi offered half of the enterprise to DZS in 2021. He stays chief govt of the remaining enterprise, which is devoted to innovation and licensing in broadband connectivity enchancment.

Cioffi continued instructing at Stanford full time till 2009, when he moved to the part-time standing he maintains as we speak.

Staying present and communicative with IEEE

Cioffi joined IEEE as a pupil member in 1976, and he has renewed his membership ever since.

“It’s been a good way to stay current, meet people, and get to know others with similar interests,” he says.

The group has honored him for his work, as he obtained the 2010 IEEE Alexander Graham Bell Medal. He holds different high awards together with the 2006 Marconi Prize and a Lifetime Achievement Award from the Broadband World Forum in 2014. He was named to the Internet Hall of Fame in 2014 and the Consumer Technology Association Hall of Fame in 2018.

Cioffi remains to be desirous about instructing the subsequent technology of communication engineers, he says. In his part-time work at Stanford he updates and teaches digital communications coursework for graduate college students.

“I tell them that digital communications goes back to smoke signals, and even earlier than that,” he says. “If you look at the opening of Genesis in the Bible, it starts with this darkness and what God sees is not good. Then, God says, ‘Let there be light.’ And he sees that it is good. What’s light? It’s an electromagnetic wave that is the fundamental component of energy and communication.

“I also tell students, ‘You’re the custodians of God’s great gift to creation, and that’s why it’s immensely satisfying to work in communications.’”