Diversity-Based Multi-Band Spectrum Sensing Policies for Cognitive and Co-exiting Radio Networks

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• Professor Visa Koivunen, Aalto University, Helsinki (formerly known as Helsinki Univ of Technology), Finland
• Tuesday 16 October 2012, 14:00-15:00
• Gabor Seminar Room, 611.

If you have a question about this talk, please contact Lauren E Noto.

This talk addresses problems in wireless communications, statistical signal processing and machine learning. This is joint work with Dr. Jarmo Lunden, Aalto University and Prof. H. Vincent Poor, Princeton University.

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 licensed frequencies in an agile manner. This means that a secondary user may access the licensed frequency when its transmission will not interfere the primary receiver. In order to identify such spectral opportunities secondary users have to sense the radio spectrum and decide whether it is idle or not. In this work a cooperative spectrum sensing policy employed by spatially displaced multiple cognitive radios is developed. The policy enables sensing multiple potentially discontinuous frequency bands simultaneously while facilitating the use of spatial diversity to mitigate the effects of shadowing and fading on spectrum sensing. 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. Moreover, we characterize the diversity order in cooperative sensing under fading channels. In order to optimize the sensing policy under time-frequency-location varying channels a greedy machine learning algorithm to prioritize the cooperative sensing over multiple frequency bands is proposed. This problem may be seen as a restless multiarm bandit problem (RMAB). We show that even such a suboptimal method is able to significantly increase the obtained throughput by the secondary network.

Brief 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. 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 has served as Nokia Visiting Fellow in a part-time basis.

This talk is part of the COMMSP Seminar series.

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