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The invention of scalable numerology: how Dr. Tingfang Ji helped bring 5G to more than just smartphones

Jun 9, 2021

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Welcome to Qualcomm Invents. In this series, we’re talking with some of Qualcomm’s most prolific inventors about their work, the impact of their inventions, and their inspiration.

Dr. Tingfang Ji, Senior Director of Engineering at Qualcomm Technologies

While earlier generations of wireless were about connecting people to each other, and then to the internet, 5G is about connecting virtually everything to everything else. But making a new generation of wireless technology work not just for smartphones doesn’t happen overnight — that took some ingenuity. Dr. Tingfang Ji, Senior Director of Engineering at Qualcomm Technologies, invented a key technology that solved this problem, paving the way to scale 5G across countless new devices and industries.

Tingfang was born in China and joined Qualcomm in 2003, where he began work on the transition from CDMA to OFDM cellular systems. Over the next decade, he made a variety of breakthroughs relating to the designs, algorithms, and standards for many of the key components in OFDM and 4G connectivity.

Scalable numerology, however, became one of Tingfang’s most notable breakthrough technologies. In 2014, he began working on the technology and methods for making 5G viable for more devices and applications than just smartphones. His idea to use the same design with an exponential scaling of the numerical system to connect to a broad diversity of devices made it super-efficient to extend cellular beyond the phone to reach both ends of the complexity spectrum – from ultra-low-power IoT sensors to ultra-low latency high-throughput VR goggles. This created a tremendous boost for 5G hardware and engineering efficiency, setting the stage for 5G to quickly scale across previously unconnected industries.

Today, Tingfang continues to lead one of Qualcomm Technologies biggest research teams in pursuit of the latest wireless breakthroughs. While still focusing on 5G, he’s already working on next-generation 6G cellular technology. To learn more about his inventions, thoughts on the future of wireless, and how others can become inventors, we sat down with Tingfang for a conversation.

When you started your career, did you ever think you’d experience such tremendous productivity as an inventor?

When I graduated with a Ph.D. from the University of Michigan, I knew I’d be doing something fun and interesting. There were so many technological advances happening in wireless. But as for invention, I really never thought I’d have hundreds of patents. My dad actually had one invention. I was so amazed, I used to think, ‘My dad is so great. He has this one patent.’ If you told me I'd have 800 patents by now, that would’ve just blown my mind. I was not expecting this.

How do you explain your constant track record of inventorship?

There are many things that need to happen to sustain this kind of invention. The first thing is, I'm lucky to be at Qualcomm, which is always at the forefront of wireless communications. If you work in an area where most problems have been solved, there isn't much to invent. But with Qualcomm, we’re always solving problems that no one has dealt with before.

The second thing, at least from my perspective, is the people you work with. At Qualcomm, we have this culture of brainstorming. People might wonder why we have so many meetings, but it’s these meetings that make the invention process so special. It makes people think and exchange information, and it makes sparks fly.

And lastly, I don't give up. I am very persistent. You don't succeed all the time, but I think if you're willing to take the extra step, make the extra effort, then you can learn more. That's the best advice I can say about how to keep inventing. By the way, those 800 patents I referred to are not my inventions alone. Those are my team’s inventions. Like I said, brainstorming requires a team of engineers who are trying to come up with solutions and patents, and I’m proud of that.

How long did it take for scalable numerology to go from idea to reality?

I think it took a couple of years. At the beginning, all we knew was that we wanted to have scaling. We stayed at the idea stage for almost a year. When we got into standards and were talking to other people, we discovered new problems. We had the framework, but it took us another year to actually hammer out the details.

For example, for something to be backwards compatible, it means you need to also fit this design into some older technology. You need to add all the bells and whistles to actually make it more applicable in more use cases. When we designed 5G at the beginning, we had this very beautiful, fully scalable design with time domain and frequency domain. These are the dimensions that we were designing. In the end, what's actually standardized is about half of what we designed.

We lost some of this other scalability because we had to sacrifice it to accommodate these other practical constraints. Although you lose some of the pure, very pretty designs, you end up building things like economical scale. There are trade-offs. It's a long, complex process.

What other communication technologies are you interested in today?

Communication, inherently, is shipping information from one point to another. But what we haven't done enough of (though 5G is already doing some of these things) is use electromagnetic waves or signals surrounding us to do something more than communication like location positioning, for example.

You can use these signals to figure something out about our physical world. It's not only about shifting the information payload, but for sensing and visioning. Hopefully that can be somewhat complementary to camera technology in terms of sensing the environment without sacrificing privacy. I think that's something that we could do in the next generation.

What advice would you give to other inventors?

You need to get your hands dirty, and you need to think big. These are two things that sometimes contradict each other, but for invention, you actually need both. If you’re only doing the dirty work, you might lose track of the big picture. You might go too deep down the rabbit hole. And if you only think big, it's superficial. You really cannot make anything out of it.

For inventors, I encourage everyone to have a very balanced approach and never be afraid of hands-on work. In our field, we do models, run simulations, and spend tons of time coding things up as needed. But you also always need to be asking, "what problem am I solving?" and “is it really a problem that needs to be solved?” If there are already sufficient solutions, you might need to find a different field or area to explore.

What would you say to young people who are interested in STEM and wonder what it’s like to be an inventor?

Sometimes, I think about what I should tell my kids. I have two girls and they sometimes ask me, ‘what should I do when I grow up?’ There's no good answer. Each person is an individual, with different preferences, who likes and dislikes different things. But in my mind, science and technology really changes society. Just look back at the last 100 years, and how much progress we’ve made. We have a feedback loop where invention leads to even more invention, which leads to economic and societal changes at such a fast pace. The heart of it is science and technology, changing our world.

Teenagers and young people often say, ‘I'm bored.’ Well, together, science and technology is a place where you'll never get bored. Every day, there are new problems to solve and if you're an inventor, you're trying to invent new things. If you’re a young kid and don't want to be bored, come to science and technology; you’ll still be learning when you're 65 years old. I have so many colleagues who are senior to me, but they keep learning new stuff. We're always discussing exciting new problems and new solutions. It's a really rewarding area to focus your life on.

Read about another Qualcomm inventor, Dr. Marta Karczewicz, who helped make it possible to stream, share, and communicate over video.

 

 

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