Performance Evaluation on Transmitter Detection Techniques for Cognitive Radio
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Date
2010-10
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Addis Ababa University
Abstract
Wireless communications and the utilization of the radio frequency spectrum have witnessed
a tremendous boom during the past few decades. Given the limitations of the natural
frequency spectrum, it becomes obvious that the current static frequency allocation schemes
cannot accommodate the requirements of an increasing number of higher data rate devices.
Cognitive Radio has come after several studies indicating that most of the allocated radio
spectrum is idle most of the time. As a result, spectrum regulation around the world is in
progress to allow unlicensed access in a non-interfering way. Cognitive radio is a candidate
technology for more efficient spectrum utilization systems based on opportunistic spectrum
sharing. But to avoid interference, effective detection of primary users is a major issue of
cognitive radio.
In this thesis work, various literature reviews on cognitive radio and detection theory by
different authors which help to understand necessary theoretical background for thesis work
have been made. Performance of energy detector, replica correlation detector and cooperative
detector has been evaluated using different performance metrics and the performance of
energy detector has been enhanced. To evaluate the performance of the detection techniques
MATLAB software has been used for simulation.
The results of performance evaluation for the detectors have shown that the replica
correlation detector (delivers Pm of less than 1%) is better than energy detector (delivers Pm of
less than 10% but greater than 1%) under both AWGN and Rayleigh fading channel. But due
to fading, single node detection is unreliable and results in a high probability of missed
detection and lower probability of correct detection. Thus, Rayleigh fading degrades the
performance of single node energy and replica correlation detectors. It has been shown that
cooperative detection helps to reduce the fading effect of single node detection and it is
concluded that cooperative spectrum detection outperforms single user energy detection and
replica correlation detector. Thus, the OR fusion rule of cooperative detection delivers better
performance. In this paper, noise uncertainty has been shown to introduce considerable
amount of degradation in the detection performance of energy and replica correlation
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detectors. It has been also shown that cooperative detection helps to reduce the effect of noise
uncertainty factor in the overall detection performance of cognitive radio.
Finally, this work proposes a new enhanced energy detector algorithm method. Its
performance has been compared with standard squared law energy detector algorithm. The
Simulation results indicate that the new energy detector algorithm method has better
performance than square law energy detector. The enhanced energy detector delivers
probability of detection 12% better than square law energy detector.
Keyword: cognitive radio, hypothesis test and spectrum detector
(energy, replica correlation and cooperative detector)
Description
Keywords
cognitive radio, hypothesis test and spectrum detector, energy replica correlation and cooperative detector