Radio Spectrum Sensing Comparative Analysis for Multiple Primary User Transmitter Detection
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Date
2021-07
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Addis Ababa University
Abstract
A radio spectrum is a particular range of frequencies used to communicate information in a
wireless communication system. It is naturally available and scarce resource. Besides to, the
dramatically increase of the wireless communication system is a critical issue and the studies
show that a certain licensed spectrum are underutilized. To solve this problem the cognitive
radio is a key technology when there is a free spectrum band of the licensed users then the
cognitive radio system permits that band for unlicensed or secondary users. In addition to that
the cognitive radio system continuously monitors at the range of primary user transmission to
minimize the interference by the secondary user’s whole opportunistically occupies on the
licensed bands. For this task the cognitive radio uses different spectrum sensing methods to
avoid the undesirable interfering and recognize the accessible radio spectrum band for secondary
users (SUs).
In this thesis, the performance of the Spherical and John’s detector spectrum sensing methods in
the presence of one and two primary users by implementing it over the typical Rayleigh fading
channel is investigated. The performance of probability of detection and Receiver Operating
Characteristics (ROC) curves within low signal-to-noise ratio (SNR) range is compared. Using
the MATLAB software with the Monte Carlo techniques are used to evaluate and analysis of the
performance of this work.
The implementation part shows a detailed comparison between the Spherical detector (SD) using
General Likelihood Ratio Test (GLRT) estimator and John’s detector (JD) using Locally Best
Invariant Test (LBIT) estimator including a single and two primary user (PU) transmitted signals
of detection. The specific, result shows the performance efficiency of detection for both schemes
with a tolerable interference level under the fading channel.
The proposed system uses GLRT estimator for SD and LBIT estimator for JD. After doing the
experiment, the result showed that JD provided the better detection performance over SD. To
illustrate this, when two PUs are detected by four SUs in cooperative scheme using SD method
at SNR range of [-2, -1] dB, the result is found to be incremented from 99.7% to 99.8%. The
same experiment is done using JD method and the result shows that the detection performance is
in the range of 99.9% and 100%.
Description
Keywords
Spectrum Sensing, Spherical Detector, John’s Detector, Rayleigh Fading Channel, Low SNR