Event
Special Seminar: Multi-user & Multi-Band Spectrum Sensing for Cognitive & co-exiting Radio Networks
Monday, July 16, 2012
11:00 a.m.-12:00 p.m.
A.V. Williams Building, Room 2460
Carrie Hilmer
301 405 4471
chilmer@umd.edu
http://ece.umd.edu
Multi-user and Multi-Band Spectrum Sensing and Access Policies for Cognitive and co-exiting Radio Networks
Visa Koivunen
Aalto University
(formerly known as Helsinki University of Technology)
Helsinki, Finland
Sabbattical at Princeton University
ABSTRACT: This talk addresses problems in wireless communications, statistical signal processing and machine learning.
Cognitive radios and flexible spectrum use provide an efficient way to exploit underutilized radio spectrum by allowing secondary users or co-existing networks to access idle frequencies in an agile manner.
This means that other users may access the frequency band if it ensures that its transmission will not interfere the primary receiver.
We propose decentralized and sequential detectors to identify idle spectrum. In this work a cooperative spectrum sensing policy for spatially displaced multiple cognitive radios and multiband scenarios is developed. Spatial diversity allows for mitigating the effects of shadowing and fading on spectrum detection. The design of the sensing policy is converted into designing and allocating pseudorandom frequency hopping patterns with desired Hamming correlation properties.
The method allows for dealing with multiple discontinuous bands of different bandwidths and priorities in a straightforward manner.
Furthermore, we jointly optimize the multiuser and multiband sensing and access using machine learning techniques. Exploration and exploitation of the time-frequency-location varying spectrum are used to maximize the profit such as sum rate. Finding an optimal solution is a difficult combinatorial problem. However, a high-quality suboptimal solution may be found very efficiently. Finally, we characterize the diversity order in cooperative sensing under fading channels.
BIO:Visa Koivunen (IEEE Fellow) received the D.Sc. (EE) degree (with honors) from the Department of Electrical Engineering, University of Oulu, Finland. From 1992 to 1995, he was a visiting researcher at the University of Pennsylvania, Philadelphia. Since 1999, he has been a Professor of Signal Processing at Aalto University (formerly known as Helsinki Univ of Technology), Finland. Since 2009 he has been Academy professor at Aalto University. He is one of the Principal Investigators in the SMARAD (Smart Radios and Wireless Systems) Center of Excellence nominated by the Academy of Finland. He was also Adjunct Full Professor at the University of Pennsylvania, Philadelphia. During his sabbatical leave in 2006-2007, he was a Visiting Fellow at Nokia Research Center, as well as Princeton University. He makes frequent research visits to Princeton University. He continues to serve as Nokia Visiting Fellow in a part-time basis. Currently he is on sabbatical leave at Princeton University, NJ, USA.
His research interests include statistical, communications, radar and sensor array signal processing. He has published more than 350 papers in international scientific conferences and journals. Dr. Koivunen received the Primus Doctor (best graduate) Award among the doctoral graduates in the years 1989 to 1994. He is a member of Eta Kappa Nu. He co-authored the papers receiving the Best Paper Award in IEEE PIMRC 2005, EUSIPCO 2006, and EuCAP 2006. He has been awarded the IEEE Signal Processing Society Best Paper Award for 2007 (co-authored with J. Eriksson). He is a member of the editorial board for the IEEE Transactions on Signal Processing and IEEE Signal Processing Magazine. He is also a member of the IEEE Sensor Array Multichannel Signal Processing Technical Committee. He is also serving at the industrial liaison board of the IEEE SP society. He was the general chair of the IEEE SPAWC (Signal Processing Advances in Wireless Communication) 2007 conference in Helsinki, June 2007.
