Featured Engineer

Interview with Alex Wyglinski

Alex Wyglinski

Alex Wyglinski - Assistant Professor of Electrical & Computer Engineering, Worcester Polytechnic Institute (WPI)

Additional Titles:

Director, Wireless Innovation Laboratory
Director, WPI Limerick (Ireland) Project Center

What are your favorite hardware tools that you use?

Both my research and educational activities are heavily focused on the design and implementation of highly adaptive, agile wireless communication systems and networks. Consequently, much of what I do at WPI involves the use of software-defined radio (SDR) platforms. Although there are numerous SDR platforms to choose from, I mostly use the Universal Software Radio Peripheral 2 (USRP2) by Ettus Research LLC for almost everything I do, ranging from the implementation and testing of prototype vehicular communication networks to teaching senior level courses in digital communication systems and SDR design.

Another hardware tool that is my favorite is my Agilent CSA N1996A spectrum analyzer. This device is frequently used by my research team and I to conduct experiments into wireless spectrum occupancy characterization, distributed spectrum sensing networks, and dynamic spectrum access algorithms. In 2008, one of my undergraduate summer research assistants wrote from scratch a Java program called SQUIRREL (Spectrum Query Utility Interface for Realtime Radio Electromagnetics) which controls the operations and parameters of the spectrum analyzer using SCPI commands and retrieves measurement data from the device and stores it on a laptop computer connected via Ethernet. As a result of SQUIRREL, it is possible to perform numerous spectrum measurements quickly and efficiently store them away for post-processing afterwards.

What are your favorite software tools that you use?

Other than SQUIRREL, which I described in the “favorite hardware tool” section, I would say that both MATLAB and Simulink are my favorite software tools that I use fairly frequently, especially the Simulink USRP2 interface blocks available in the Communications Blockset of MATLAB 2010b. When it comes to validating new concepts and ideas via accurate computer simulations, MATLAB and Simulink are always the first software tools that I utilize. Regarding the Simulink USRP2 blocks, there is a WPI story behind the development of these blocks. Via a collaborative relationship between the Mathworks and my research team at WPI, several projects have been pursued over the past three years that have been geared towards the integration of SDR prototyping hardware with MATLAB and Simulink. Consequently, one of the first projects was to develop a prototype interface between Simulink and the USRP2 SDR platform. My former MS student, Michael Leferman, ultimately created these prototype transmitter and receiver blocks for his thesis, and served as a starting point for additional activities to integrate Simulink with the USRP2 hardware.

How did you get into wireless communication systems engineering and when did you start?

Ever since I was about five years old, I have always been mystified by society’s ability to communicate information wirelessly from one location to another without any cables. Although I am not sure what it is exactly that amazes me about wireless communications, whether it is the invisible nature of the data transmission or the freedom associated with untethered communications, I do know that once I got hooked on wireless communications starting with my very own pair of Fisher Price walkie talkies (I still have them in my office!!), I was always thinking about how all this wireless stuff really worked. Consequently, this guided my educational pursuits towards the sciences and technology, and ultimately towards electrical engineering.

What is on your bookshelf?

Lots and lots and lots of communication systems engineering, digital communications, software-defined radio, and stochastic processes textbooks. One item on my bookshelf that I am particularly fond and proud of is my first book, entitled: “Cognitive Radio Communications and Networks: Principles and Practice” (Academic Press, December 2009). Co-edited with Maziar Nekovee (BT Research) and Tom Hou (Virginia Tech), and co-authored with dozens of international experts in cognitive radio communications and networks, this is the first textbook published on this subject. Although it took nearly two years to complete, it was definitely a worthwhile experience. In fact, I hope to include another textbook that I am in the process of writing on the subject of software-defined radio experimentation and design.

Why did you decide to pursue a career in academia?

I have always been very curious about how things work, ranging from computers to automobile engines. Ever since I was a young boy, I would try figuring out the details on how are particular device would operate while the rest of the world would take it for granted. During my childhood, there were numerous occasions when I thought the best way to understand the operation of a device was to take it apart, much to the chagrin of my parents’ especially when I dismantled the family stereo radio system. Nevertheless, my curiosity about why various technologies worked coupled with my passion for improving upon the current state-of-the-art and my desire to disseminate knowledge and discoveries to the masses appeared to be a suitable match for a career in academia. Although I graduated with my Ph.D. in 2005 and started my career in academia soon afterwards, I still feel like a graduate student, albeit with a significant increase in the number of responsibilities. Nevertheless, pursuing a career in academia and work with the next generation of electrical and computer engineers has kept me young at heart and still full of passion and enthusiasm for this subject.

What has been your favorite project?

Hmmmm … this is a hard question. There have been so many exciting, interesting, and fun projects that I have participated in throughout my career that I am not sure if there is a definite favorite. I think the most memorable projects that I have performed over the past several years all had to deal with wireless spectrum occupancy measurement and characterization. The first project took place in 2006 when I was at the University of Kansas. Together with a couple of MS students, we proceed to take TV spectrum measurements at various distances from a TV broadcasting antenna approximately 20 miles west of Topeka. It was fun being outside of the laboratory and trekking across the Konza Prairie collecting wireless spectrum measurements that were ultimately published in several peer-reviewed venues.

Another project involved taking wireless spectrum occupancy measurements across nearly 3 GHz (88 MHz to 3 GHZ) for four cities (Worcester, MA; Rochester, NY; Buffalo, NY; Pittsburgh, PA) at five locations per city. This NSF-sponsored measurement campaign was conducted over a two week period over Summer 2008 with two NSF REU (Research Experience for Undergraduates) students and one PhD student packed into a rented minivan with a spectrum analyzer, antennas, and a bunch of other pieces of equipment. During this campaign, we took measurements from every possible location that was available to us, including the roofs of parking garages and parking spots across the downtown areas of the cities involved in this study. At the end of the study, several gigabytes of spectrum measurement data were collected, post-processed, and analyzed, yielding new and interesting insights on how spectrum occupancy changes as a function of spatial coordinates within an urban environment.

Yet another interesting project was conducted as part of some research collaborations with the Toyota InfoTechnology Center U.S.A. during Summer 2009, when my Ph.D. student (Srikanth Pagadarai) and I took ten frequency sweeps of TV spectrum at two mile intervals along the entire Massachusetts portion of Interstate I-90. These sweeps would ultimately serve as a resource for evaluating designs of vehicular dynamic spectrum access (VDSA) networking systems. One of the highpoints of this measurement campaign was a side trip to Bunker Hill, which overlooks the City of Boston, at around midnight of Friday 12 June 2009 when the DTV transition occurred. Using the spectrum analyzer and SQUIRREL software tools, my PhD student and I observed how history was being made in the US with the deactivation of all analog TV channels and the reshuffling of several digital TV channels. It was quite a memorable experience!

What are you currently working on?

At the moment, there are at least three projects that I am currently working on with my research team. The first project involves the design of a communication system that is capable of extracting wireless signals from a mixture of partially overlapping wireless transmissions using a well-known signal processing technique referred to as “blind source separation”. Sponsored by the Office of Naval Research, the goal of this project is for a wireless communication system to extract a target wireless transmission that is being exposed to a substantial amount of interference, including jamming fields.

The second project is sponsored by the Toyota InfoTechnology Center U.S.A. and it involves the implementation of a vehicular networking test-bed that can perform multi-hop relay communications and dynamic spectrum access. A team of undergraduate and graduate students have worked over the past nine months to construct a robust system using the USRP2 platforms and GNU Radio capable of operating in highway driving conditions. Just several weeks ago, nine of my students and I took five cars out for an experiment across a 60-mile distance in order to verify the functionality of the proposed implementation. Four of the cars were equipped with USRP2 platforms while the fifth car operated the spectrum analyzer that was monitoring the entire experiment. The results from this experiment were truly amazing, and my students and I are in the process of submitting a conference and journal paper based on this project.

Finally, the third project involves establishing a link between the amount of available wireless spectrum within a geographical region and various socio-economic factors such as housing costs, education levels, or employment statistics. Although there have been several studies on assessing the amount of available spectrum within a specific region, there has not been any work yet on how this information is quantitatively linked to modern society. This project is being pursued by my Fulbright Fellow and PhD student, Sean Rocke.

Do you have any advice for the next generation of wireless communication systems engineers?

Given the significant paradigm shift regarding how wireless communication systems are being designed, how they are operated, and how they are accessing wireless spectrum, it is very important to think creatively and look at other disciplines in order to gain a different viewpoint on how a communication system should work. This area is currently in a state of flux, and the rules are being rewritten as we speak … use this opportunity to be creative and shape the future of wireless communications and networking. Using software-defined radio, what was considered impossible a decade ago can now be implemented in a relatively short period of time and with very little capital investment. Just remember that the future of wireless depends on our ideas now and making them a reality.

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