Mitigating Wave Scattering


The following article appeared in the Spring 2020 issue of Focus on Materials, a quarterly bulletin produced by the Pennsylvania State University's Materials Research Institute.  Professor Ram Narayanan of Penn State's College of Engineering worked with Remcom to produce a 5G millimeter wave coverage concept using existing AT&T towers in State College, PA, showing ray path predictions generated in Wireless InSite.  Here Professor Narayanan discusses the challenges facing 5G signal propagation.

It is time for us to start ramping up out footprint in the 5G world, because everyone else is doing 5G, according to electrical engineering’s Ram Narayanan. 

“5G is a new scheme for fast and very reliable communications. It connects humans with machines, the internet of things, provides streaming video and audio,” he said. 

As we move into higher frequencies, first 10 gigahertz, then 30 gigahertz, the problems of short range and interference with obstacles, such as trees and even oxygen molecules in the atmosphere appear. Unlike radio waves, which can travel long distance and can pass through walls and other obstacles, 5G signals are short range and require a much higher number of base stations. These are the problems Narayanan is trying to overcome. 

Penn State has been studying various aspects of 5G and has considerable expertise in areas that could easily translate into 5G, but so far there has been no coordinated efforts. There are people in electrical engineering who are looking at new designs for antennas (as carrier waves shrink, the size of  antennas shrink). Computer engineering is looking at modulation - 5G requires new signal schemes to be transmitted. It requires people like Narayanan who are working on propagation, for instance, what happens when the signal goes into a building with multiple reflections? 

“We require people working in electromagnetics and in signal processing. We require materials people, because some of these designs require exotic materials. All of these have to come together. In this, the College of Engineering can play an important role, because I do not believe we are tapping our full potential. This is the time we need to have a cohesive approach so we can go after bigger funding,” he said. 

Narayanan’s Research

Narayanan is working on microwave engineering, which includes radio wave propagation through the atmosphere. He is looking at what happens when radio waves get scattered by obstacles in nature. He studies how different frequencies can be used for different applications, for instance using lower frequencies to look for land mines. And most important for 5G, propagating electromagnetic energy inside buildings. 

“If you look around inside a building, there are so many ways the waves can be deflected. And when they are deflected, the come back at different phases. We are working to mitigate those types of issues,” he concluded.

Prof. Ram Narayanan 

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