Researchers collaborate to end the scarcity of wireless spectrum with dynamic and efficient access.

The volume of radio communications has seen accelerated growth in recent years in order to accommodate traditional and emergent technologies. Modern radio communications include phone calls, text messages, photos, video, and data for smartphones and other mobile devices; television and radio broadcasts; public safety radio networks; and global positioning systems for navigation devices and applications. These communications travel over the air in the form of electromagnetic sine waves differentiated by their specific frequency or range of frequency. No two transmitters can share the same frequency in a single geographical area, so service providers must lease portions of wireless spectrum from the Federal Communications Commission. With the rapidly-increasing demands of new wireless services and applications for anytime/anywhere connectivity, there is a growing spectrum-scarcity problem.


Dr. Yingying Chen

Experts like Dr. Yingying Chen and Dr. Yi Guo of the Department of Electrical and Computer Engineering at Stevens Institute of Technology are working to design more efficient systems for the allocation and management of spectrum, particularly through the use of technology called cognitive radio that scans wireless spectrum dynamically for the clearest bands and switches seamlessly, establishing intelligent and efficient utilization of radio spectrum while securing users from abuse and malicious attacks. These dynamic systems are critical for future wireless networks because much of the spectrum which is already spoken for sits unused at any given time. Dr. Chen and Dr. Guo have been awarded a grant from the National Science Foundation to investigate consensus-based cooperative spectrum sensing that potentially enables robust and efficient cognitive radio networks.

Dr. Guo

Dr. Yi Guo

“Experts and leaders in industry, government and academia have marked the expansion and more effective allotment of wireless spectrum as national priorities,”says Dr. Michael Bruno, Dean of the Charles V. Schaefer, Jr. School of Engineering and Science. “Dr. Chen and Dr. Guo’s research will aid in efforts to more efficiently utilize the wireless spectrum which is a critical billion-dollar resource for industry and technologies that are deeply embedded in modern society.”

Cognitive radio networks (CRNs) have emerged as a promising solution to alleviate the problem of spectrum-scarcity. CRNs use dynamic spectrum access to allow “secondary users” to operate on a portion of spectrum that has been reserved by “primary users” for another use, but is not being utilized at that time.

Future CRNs will consist of heterogeneous devices such as smartphones, tablets and laptops moving continually in a geographic area. In order to maintain efficiency in future radio systems, CRNs need accurate and robust sensors that seek out vacant spectrum, allowing nodes to dynamically and seamlessly switch the channel of transmission. Additionally, CRNs need effective authentication to identify unauthorized spectrum usage.

Dr. Chen and Dr. Guo aim to utilize consensus-based cooperation featuring self-organizable and scalable network structure to capture the swarming behaviors of spectrum users and provide cooperative spectrum sensing in a fully distributed manner. By using a combination of control theory and machine learning techniques, the project designs secure, weighted-average consensus for cooperative spectrum sensing. It not only captures the swarming behaviors in CRNs with heterogeneous devices, but takes into account practical channel conditions. The collaborators are using dynamic signal strength mapping to develop robust localization approaches with the ability to localize multiple malicious users who also might be occupying the spectrum without authorization, thus preventing access by legitimate users. The new techniques will be validated using a testbed which is to be deployed on the Stevens campus, enabling system demonstrations to industrial collaborators such as AT&T Labs.

According to Dr. Yu-Dong Yao, Director of the Department of Electrical and Computer Engineering, “This project capitalizes on multi-disciplinary knowledge in control systems and machine learning techniques to revolutionize spectrum efficiency in cognitive radio networks, potentially alleviating the crowdedness of spectrum occupancy and supporting the co-existence of heterogeneous devices.”

Dr. Chen and Dr. Guo have collaborated for many years, supervising students and collaborating on multiple publications. “This grant is the product of active and sustained collaboration, and it is strongly informed by our respective expertise,” says Dr. Chen.

Dr. Yingying (Jennifer) Chen co-authored the book Securing Emerging Wireless Systems in 2009 and published over 70 journal articles and referred conference papers. She is the director of Data Analysis and Information Security (DAISY) Lab at Stevens. She is the recipient of the NSF CAREER Award 2010 and Google Research Award 2010. She was honored with a New Jersey Inventors Hall of Fame Innovators Award 2012. She was recently awarded a grant from the Army Research Office for innovative research on mobile wireless security. Her research has been reported in numerous media outlets including the Wall Street Journal, MIT Technology Review, NPR, and CNET.

Dr. Guo is an expert in power system stabilization and decentralized control, multiple robot motion planning and navigation, and stability modeling and congestion control of computer networks. She was recently awarded an NSF grant to deploy robot teams that monitor propagation of underwater oil leaks. She was also previously awarded an NSF grant to investigate a rigorous mathematical approach to the analysis and control of coupled semiconductor laser systems. She is a senior member of IEEE, and Meeting Finance Chair of Conference Activities Board of IEEE Society of Robotics and Automation.

The project also carries out a broad range of education and outreach activities to encourage students to pursue careers in the fields of science and engineering. Research results will be disseminated to academia and industry through presentations and publications in meetings, conferences and journals.

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