|
ECE Colloquium March 10th at 11:00am, in the Hill Conference room (Lebow Engineering Center, room 240)
Collaborative Spectrum Sensing for Cognitive Radios
by Jarmo Lunden, Helsinki University of Technology
Abstract:Spectrum utilization is currently becoming increasingly inefficient. Current
spectrum regulation is based on a fixed allocation policy. The spectrum is
divided into frequency bands each allocated to different system.
Consequently, there is high demand for more flexible and efficient spectrum
allocation. Cognitive radios have been suggested as an enabling technology
for dynamic allocation of spectrum resources. Cognitive radios sense the
radio spectrum in order to find opportunities for agile spectrum use.
Moreover, spectrum sensing is critical for managing the level of
interference caused to the primary (legacy) users of the spectrum. Through
sensing cognitive radios acquire information about the radio operating
environment. This enables the cognitive radio to adjust its operating
parameters, such as carrier frequency, transmit power, and waveforms
dynamically in order to provide the best available connection to meet the
user's needs within the constraints on interference.
In this talk, collaborative cyclostationarity based spectrum sensing methods
are introduced. Cyclostationary processes are random processes whose
statistical properties are periodic in time. Many of the signals used in
wireless communication systems possess this property. Collaboration among
the cognitive radio terminals allows for mitigating the effects of shadowing
and fading through spatial diversity, improves the detection performance,
and provides a larger area for the cognitive radio system. This talk
examines collaborative detection techniques combining local test statistics
from many secondary users. In order to reduce the amount of overhead traffic
due to the collaboration censoring of uninformative test statistics is
considered. Simulation experiments demonstrating the reliable performance of
the cyclic detectors, collaboration gains, and censoring benefits even under
very strict constraints on communication rates are provided.
Bio: Jarmo Lunden received the M.Sc. (Tech) degree with distinction in
Communications Engineering from the Dept. of Electrical and Communications
Engineering, Helsinki University of Technology (TKK), Finland, 2005. Since
2005, he has been pursuing doctoral degree at TKK. Since September 2007, he
has been a visiting researcher at the University of Pennsylvania,
Philadelphia. His research interests include cognitive radio and radar
interception and identification.
In 2005, Mr Lunden received the Pattern Recognition Society of Finland's
Award for the Best Master's Thesis in the field of pattern recognition.
|
