2007-2008

ECE Faculty Profile: Alexander Wyglinski

Prof. Alexander Wyglinski

Professor Alexander Wyglinski is one of the two newest professors in the Department of Electrical and Computer Engineering at WPI, joining us in August, 2007. Before WPI, he served as a faculty member at The University of Kansas.  A brief review of Dr. Wyglinski's background and research interests can be found online in a recent article announcing ECE's new faculty members for Fall 2008.

Since his arrival at WPI, Dr. Wyglinski has immersed himself in many activities currently underway within the ECE department.  Among his start-up initiatives, he has created the Wireless Innovation Laboratory, a wireless communications research facility consisting of a team of both undergraduate and graduate students equipped with state-of-the-art equipment. Most of the research activities currently underway at the Wireless Innovation Laboratory focus on open challenges in software-defined radio (SDR) and cognitive radio communication systems and networks.

According to Dr. Wyglinski, an SDR is a wireless platform implementation whose functionality is almost entirely based in executable software, as opposed to conventional wireless devices, where both the digital signal processing and digital communication algorithms are implemented using integrated circuits. Such an implementation presents numerous advantages, including software-based device upgrades as well as a flexible selection of appropriate software modules supporting different wireless functions.  To automate this selection process, an artificial intelligence (AI) can be employed by the SDR, resulting in a cognitive radio.

SDR and Cognitive Radio to the Rescue!

Numerous international wireless experts, including Dr. Wyglinski, are actively conducting research into solving the radio frequency (RF) spectrum scarcity issue currently faced by the wireless market.  Traditional RF spectrum allocation is performed by governmental regulatory agencies, such as the Federal Communications Commission (FCC), who are responsible for licensing finite frequency bands to various entities, as well as defining transmission constraints that ensure minimal spectral interference between wireless devices.  Since licensed entities possess exclusive rights to their allocated RF spectrum, this prohibits unlicensed transmissions from transmitting in these bands since they may cause unintentional spectral interference with the incumbent license holders.  However, with almost all of the prime RF spectrum (i.e., 100 MHz to 3 GHz) already licensed, coupled with the growing number of wireless users, applications, and services, there are initial indications that the traditional licensing framework will be unable to keep up with the growing demand for RF spectrum.

Conversely, numerous spectrum measurement studies across the nation and around the world show that most RF spectrum is actually underutilized.  As a result, the spectrum scarcity problem we are currently facing is artificially generated by the traditional licensing framework, which does not ensure the efficient usage of spectrum by license holders.  This is analogous to the scenario where one roommate purchases an expensive TV and forbids the other roommate to ever watch it, even when TV is not in use.  Thus, electrical and computer engineers, along with economists, regulators, lawyers, and other experts are rethinking the way RF spectrum is utilized.

One solution to the artificial spectrum scarcity problem, which Dr. Wyglinski and his team at the Wireless Innovation Laboratory are investigating, is a new spectrum allocation paradigm called dynamic spectrum access (DSA).  The DSA paradigm enables an unlicensed device to temporarily borrow unoccupied RF spectrum from the incumbent licensed holder as long as it can simultaneously respect the rights of the incumbent licensee.  As a result, the efficiency of the spectrum utilization is greatly enhanced while maintaining backwards compatibility with the traditional spectrum licensing agreements.  Referring back to the story of the two roommates with the new TV, this is equivalent to the scenario where one of the roommates can temporarily use the TV when the other roommate is not present. More importantly, when the other roommate returns, the roommate initially watching the TV must immediately discontinue use and return everything to its original state, including cleaning up all the popcorn from the couch.

Two key technical challenges associated with DSA are accurate sensing of unoccupied frequency bands by the unlicensed wireless devices and the ability to rapidly reconfigure in order to quickly get out of the way of an incumbent licensed transmission.  Both challenges can be addressed using SDR and cognitive radio technology, where these devices can be designed to be spectrally aware of their transmission environment while simultaneously avoiding interference with incumbent transmissions.

In addition to enabling the DSA paradigm for alleviating the spectrum scarcity problem, SDR and cognitive radio can also be used to solve inter-operability issues between the communication infrastructures of different government, public safety, and military organizations, especially in disaster relief scenarios.  For instance, in the aftermath of Hurricane Katrina, where most of the commercial telecommunication infrastructure was inactive due to the lack of power, it quickly became apparent that the police departments, fire departments, emergency services, and National Guard were unable to effectively communicate with each using their conventional radio sets, since the different organizations were all employing incompatible communication protocols. However, had these groups all employed SDR- or cognitive radio-enabled devices, their wireless devices would have been able to translate between the plethoras of communication protocols, and they would have been able to communicate with each other.

Current Research Projects

In 2007, Dr. Wyglinski was the recipient of a National Science Foundation (NSF) Wireless Networks grant to support his research project entitled: “Wireless Network Quantification of Spectrum Availability for Wireless Network Access.”  Together with Ph.D. student Srikanth Pagadarai, who earned his M.S. degree at The University of Kansas under Dr. Wyglinski’s supervision, and WPI junior Alex Camilo, Dr. Wyglinski and his research team are investigating how RF spectrum is utilized in twenty mid-size U.S. cities across the nation. Their first task is to conduct a theoretical assessment of the spectrum availability in these twenty cities and then take actual spectrum measurements for a subset of these cities. They will then quantitatively evaluate how close the theoretical and measured spectrum availability results match.  Their second task is to take these measurements and develop an electrospace model that mathematically characterizes the frequency, time, and spatial behavior of urban RF spectral usage. Finally, Dr. Wyglinski's research team will conduct a long-term spectral availability trend analysis for the city of Worcester, MA by examining the spectrum occupancy changes over several years at intervals of every three months.

Image on the right: MS student Kevin Bobrowski prepares a software-defined radio for experimentation while Professor Wyglinski and PhD student Si Chen calibrate a spectrum analyzer for collecting frequency measurements / photo by Vivek Varshney

Another research project that Dr. Wyglinski is leading focuses on the development of practical optimization algorithms for high-speed wireless devices using SDR or cognitive radio technology in order to increase the overall data transmission rates.  Currently, most wireless standards for wireless local area and metropolitan area networks (WLANs and WMANs) employ a transmission technique called orthogonal frequency division multiplexing (OFDM). This technique possesses several imporant characteristics, such as its ability to send large amounts of data reliably using a divide-and-conquer approach; small amounts of information transmitted simultaneously via multiple low data rate carriers. Working with Dr. Wyglinski on this project is M.S. student Kevin Bobrowski, who earned his B.S. degree in ECE at WPI in 2007.  At the core of every OFDM system is a Fast Fourier Transform (FFT), which is used to transmit the parallel low data rate carriers. However, in many scenarios, the FFT is often inefficiently utilized.  As a result, both Dr. Wyglinski and Mr. Bobrowski are conducting research into practical FFT optimization approaches for OFDM-based wireless devices using SDR and cognitive radio.  The goal of these optimization approaches is reduce the amount of device resources being utilized, as well as increasing the execution time, decreasing the power consumption, and reducing the overall physical space of the OFDM implementation on an SDR or cognitive radio platform.

A Fresh Perspective

When asked to provide an opinion on his experience with WPI, Dr. Wyglinski stated: "[It] is an amazing and friendly place. Ever since I joined in August 2007, everyone has been extremely supportive; there is a real sense of community. The students here are excellent with respect to their ability to apply the knowledge they've learned in class.  Moreover, WPI provides an environment where I can make substantial contributions to both the nation as well as the rest of the world. There are numerous resources available for conducting research and disseminating my findings. Overall, I really love it here, especially seeing how everyone is keen about innovation in order to make the world a better place." 

Related Links

Acknowledgements

Article research and draft provided by Rachelle L. Horwitz, a WPI ECE senior.

February 29, 2008