Performance Enhancement of Spectrum Detection Using Hybrid of Energy and Matched filter Detection Algorithms in Cognitive Radio

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Addis Ababa University


Nowadays, there has been an increase in wireless technologies, which are used for variety of applications and services. The need of using wireless services and applications also increased from day to day that brings a higher demand on radio spectrum leading to shortage and congestion. In addition, the fixed assigning of a radio spectrum to a specific user leads to under-usage of available spectrum which brings wastage of spectrum. After several studies, cognitive radio exists to minimize problems regarding to the limited and wasted spectrum resource. This technology, cognitive radio searches a free or unused portion of spectrum and enables secondary users to access that free part of spectrum. Spectrum sensing methods are very important in cognitive radio for detecting the availability of unused spectrum and allow secondary users to use the spectrum band in non-interference manner. Energy and matched filter detector are the most common type of transmitter detection techniques to detect the user. Even though energy detector used most of the time, its performance of detection poorly decrease and degraded at weak received SNR and noise uncertainty scenario. Beside of this, matched filter detector is an alternative and good sensing algorithm in lower SNR value, since it enlarges SNR of the signal received and gives a better performance compared to energy detection. This thesis aims to develop an efficient hybrid detection technique, by combining energy with matched filter detector to enhance energy detector at low SNR value in specific, and improve spectrum detection performance in general. The performance of proposed hybrid detector with conventional energy detector and other hybrid detection technique is analyzed and compared. Receivers operating curve (ROC), false alarm probability, detection probability and SNR values are the basic performance evaluation matrices. MATLAB software has been used to evaluate the performance of detection technique. In simulation result, the detection performance has been evaluated based on the plotting Pd vs Pf, Pd vs SNR, Pmd vs SNR and Pd vs noise uncertainty for both fading and non-fading channel model which are Rayleigh and AWGN channel respectively. From the result obtained, the proposed hybrid detection performs better than energy detection and other hybrid detection under AWGN and Rayleigh fading channel. The proposed hybrid detection enables to reduce the effect of noise uncertainty and fading on detection performance.



Spectrum sensing, Cognitive radio, Energy detector, Matched Filter Detector, Fading Channel, Primary user, ROC