Theodore Rappaport: At the Forefront of 5G

The IEEE Fellow is a leader in creating the fifth-generation wireless network

22 August 2014
Photo: NYU

The number of smartphone users around the world climbed to about 1.75 billion this year, and that number is expected to rise rapidly in the next three years as the phones’ prices drop, according to a report by eMarketer, a market research firm. Add to that the billions of sensor-embedded devices expected to be connected to the Internet of Things (IoT), and it’s easy to see why the current wireless network might soon have difficulty bearing the load.

That’s why wireless experts from academia and industry are teaming up to build fifth-generation (5G) technologies. One leader of the effort is IEEE Fellow Theodore “Ted” Rappaport, whose work at New York University, in New York City, spans multiple fields. Rappaport is a professor of electrical and computer engineering at the NYU Polytechnic School of Engineering, a professor of computer science at NYU’s Courant Institute of Mathematical Sciences, and a professor of radiology at the NYU School of Medicine at the Langone Medical Center.

Rappaport is founder and director of NYU WIRELESS, an academic research center that combines wireless engineering, computer science, and medicine. He was a keynote speaker at the first Brooklyn 5G Summit (B5GS), held from 23 to 25 April at NYU Polytechnic. The event brought together wireless and mobile industry representatives with research and development leaders in academia, business, and government to explore the future of 5G technology.

The Institute recently interviewed Rappaport about what 5G will mean for everyday smartphone users, the challenges he and his team have encountered in developing the new network, and how he became interested in all things wireless.

What major differences will we see with 5G compared with today’s 3G and 4G networks, and how will it affect the IoT?

Smartphone users will see a huge increase in speed and data rates—many more gigabits per second. They’ll also experience much lower latency, meaning they will deal with shorter wait times while loading apps and websites. The network itself will involve the convergence of cellular and Wi-Fi, so that smartphone users will not have to rely so much on their data plans, because they'll be able to connect to more Wi-Fi hotspots.

The new network will also make use of the millimeter-wave spectrum—a largely unexplored part of the electromagnetic spectrum that offers huge opportunities for unprecedented large bandwidths and data rates.

And 5G should be a major boost for the IoT. With much greater capacity and bandwidth, the new network will be equipped to support the onslaught of devices and unforeseen applications.

What challenges are you and other researchers facing in developing 5G?

Building a full-scale millimeter-wave mobile communications network includes many challenges. Many of these involve upgrading current cellphone technologies so the devices can be made smaller, faster, and more powerful.

Today, most cellphones use one or two omnidirectional antennas, which are the size of the handset’s case. The wavelength for cellular is about 15 centimeters, so antennas can occupy a large area of the device and have little directionality or gain. But as we move up to millimeter-wave frequencies, the wavelength of the radio wave becomes much smaller—about the size of a fingernail—so it becomes possible to put many dozens of antenna elements in a handset. And these antennas can be electronically phased to send and receive signals more efficiently. They can also pick up a lot of energy from reflections and wave scattering from buildings, walls, and other objects. The challenge is to design these new, tiny high-gain phased-array antennas so that they work well inside the handset.

We are also working to create baseband-processing techniques that will allow smartphones to handle massive data rates.

What were some interesting takeaways from B5GS?

The event showed there is much to learn, but there is a lot of optimism that 5G, working at frequencies well above 6 gigahertz (compared with today’s 2 GHz), is not only feasible but also will likely become the standard. The summit described the various pieces that are beginning to come together to create entirely new types of wireless systems that exploit directional antennas and new cellular architectures with smaller cells to compensate for the limited range of millimeter wavelengths. We are already planning next year’s summit, to be held on 9 and 10 April.

What other projects are you and your team working on at NYU WIRELESS?

We are doing many exciting things in the health care field. Projects include developing brain implants for the detection and mitigation of epilepsy. We are also finding ways to more accurately map the brain’s activities. As for radiology, we are developing new digital signal-processing techniques to provide real-time MRIs with extremely high resolution. The team is also developing apps and programs for wireless devices that will help people with chronic diseases stay connected to their doctors and be able to keep tabs on their health after they’ve left a hospital or clinic.

Additionally, we are studying how exposure to heat from electromagnetic signals transmitted by wireless devices affects people’s health, and are exploring ways to make future millimeter-wave wireless devices safe to use on a daily basis.

What sparked your interest in wireless communications, and what inspired you to teach others about it?

I got hooked on wireless at the age of 5 when my Grandpa Carl showed me his antique Philco shortwave radio. We spent hours listening to shortwave broadcasts and Morse code messages. That same receiver still works. My wife had it restored as a Valentine’s Day present, and I love to listen to it when I want to unwind or reflect. I have been an avid ham radio operator since I was 14 (call sign N9NB). My experiences as a teenager led me to go on to teach Morse code and radio theory as an adult. I also encountered great teachers—and many wireless communications pioneers—at Purdue University [in West Lafayette, Ind.], where I earned my bachelor’s, master’s, and doctoral degrees in 1982, 1984, and 1987.

How has your involvement with IEEE benefited your career?

IEEE has been wonderful to me ever since I joined the student chapter at Purdue in the early 1980s. For the past few years, I have served as program executive for the IEEE Global Communications Conference (Globecom), one of the IEEE Communications Society’s flagship conferences. This year’s Globecom will be held for the first time in Austin, Texas, from 8 to 12 December.

I have also served on the boards of governors of both the IEEE Communications Society and the IEEE Vehicular Technology Society—which has given me many opportunities to volunteer and help others.

Through IEEE, I have made lifelong friends. And it has brought a great deal of meaning to my career and life. I urge all my students to join IEEE because it’s a wonderful, lifelong association for any electrical engineer.

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