How Qualcomm Inventor Dr. Yeliz Tokgoz's Ideas Improve Coverage and Capacity in 5G
We often take for granted the fact that our phones automatically connect to the nearest cell tower. But behind this simple-seeming fact are thousands of hours of inventing, testing, and problem-solving by some of the world’s smartest people. Dr. Yeliz Tokgoz, Principal Engineer in the Wireless R&D Division at Qualcomm, is one such bright mind who has dedicated her career to solving these fundamental cellular technology problems – and she can tell you exactly how much effort has gone into making sure your phone can connect smoothly and quickly to the cell network.
The following conversation has been lightly edited for clarity and length.
Thanks to your work in 5G, we benefit from all kinds of network enhancements. Can you tell us a little about what your 5G inventions enable for everyday users?
Each new cellular generation is about solving problems and growing capabilities. These days, there are a lot more devices that need to be connected to the same cell network – and not just phones, but smartwatches, cameras, computers, security systems, and now even cars.
With 5G, we've greatly enhanced mobile broadband network efficiency, coverage and data rates, but we also optimized support for diverse new devices and use cases to bring connectivity to every aspect of our lives. My work focused on providing that high-speed, reliable, and consistent wireless coverage, wherever you are — whether you're outside, close to a cell tower, in a busy city center or a rural area. This is the kind of fundamental end-to-end system-level approach we take, and have been since even my 3G days.
Can you tell us a little about how coverage works in cellular technologies?
Coverage is a complicated concept, but it generally revolves around the foundation of what your phone does: sending and receiving signals to a cell tower. It starts with network planning and deployment by the operator, where they want to place towers. If it's a very high-demand area, for example, operators must densify to be able to provide service to a large user base. We try to make their jobs easier with innovations that increase the efficiency of the networks and extend the coverage of each cell tower. Coverage is not just a matter of improving your signal, but also managing interference from other undesired signals– they work hand in hand. We want to make sure that operators can achieve good data rates even where the users are farthest from the cell tower and might experience interference from other towers in the vicinity.
These cell towers often use highly directional transmissions based on massive MIMO technology. For example, one of the inventions I worked on involves determining the interference profile experienced by a device at different locations from the tower. This is done through identifying neighbor base stations and their directional transmit beams that might create interference. When a device wants to send and receive data at one of those vulnerable locations, coordination between base stations can be initiated to ensure that while that device is being served, neighbor base stations can avoid concentrating transmit power along the device’s direction.
The other side of the story is about spectrum. When you have a low-frequency spectrum, the propagation conditions are better, and you can get extended coverage. But low-frequency spectrum is very scarce — it's almost fully utilized — so there's not much available to address the increasing demand. With each generation, we're moving to higher and higher spectrum bands. Some of our innovations are related to making sure that we get comparable wide-area coverage at these high frequencies as we do with the low frequencies. We also work on how we can make best use of a range of different bands to optimize coverage and meet the requirements of the end-user. This is really hard to do – but at Qualcomm, hard problems always seem to have a way of getting solved.
How would you describe the culture of innovation at Qualcomm?
It’s crucial to understand that we don't just sit around and come up with ideas, then say, “Okay, let's do it this way.” Qualcomm is always at the forefront. A huge part of what we do is to simulate, analyze, enhance, prototype, and test our ideas. We have sophisticated analysis tools which allow us to test things in simulated environments – helping to refine our ideas faster. Often, we want to test these ideas in real-life environments. Because our ideas are quite cutting-edge, there aren’t existing prototypes or test devices, so we just develop our own and try them out in our campus over-the-air network. These capabilities provide us with great insights into the problems of real systems, and how our ideas improve performance. It's not just an innovation for innovation's sake, but innovation to solve real-life problems in a practical manner.
Do you have any unique perspectives or insights from your personal experience about being a woman inventor?
Unfortunately, the gender gap is there. I see fewer females in my field and that naturally leads to having fewer female inventors. I personally have always considered myself fortunate to work at Qualcomm, because I've never felt any negative gender bias in my group. But the gender bias certainly exists in many places, and I think we should encourage women to be more confident and realize that they can be creative, effective problem solvers. Gender doesn't play a role in the invention process, right? I have two daughters and I'm encouraging them to go into STEM. Hopefully, with newfound awareness, this issue continues to improve and more girls will seek STEM careers.