10515

9698

كارشناسي ارشد

مخابرات

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1394

نه، 77ص.: مصور، جدول، نمودار

عليمحمد دوست حسيني

سعيد صدري

1396/10/04

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID9698

Wavelet Transform Based Dynamic Spectrum Sensing Zohreh Mousavi Zs moosavi@ec iut ac ir Date of Submission Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Ali M Doost Hoseini alimdh@cc iut ac irAbstract Dynamic spectrum access has been proposed as a solution to face spectrum scarcity on one hand andthe high demand for accessing it on the other hand Cognitive radio has been suggested as a key technologyto deal with these issues using the spectrum opportunistically in changing environments Users ofcognitive radio as the secondaries need to sense the presence of primary or licensed users periodically andquickly and if there were no activity acquire the license of using the frequency band In order to achievehigher throughput for secondary users and also limit interference with primary users by quick evacuation ofthe channel at the moment of their presence the sensing cycle should be short and effective However thedetection performance is at risk due to multi path fading and uncertainty about the power of disturbance Inorder to circumvent these effects cooperative sensing is discussed as an effective method for providingspatial diversity However cooperative sensing imposes cooperative overhead Overhead refers to issueslike additional sensing time report delay energy consumption etc In this thesis spectrum sensing basedon wavelet transform is studied as a method for the detection of active primary user or spectrum hole withenergy approach After denoising the signal that is received by wavelet spectrum sensing is examinedin thepresence of generalized Gaussian noise In another arrangement with the assumption of the knowledge ofprimary signal power spectrum and using the concepts of wavelet in orthonormal multiresolution space determination of a wavelet with amplitude response corresponding to the square root of the spectrum ispursued This wavelet is applied as a band pass filter to the received signal in both individual andcooperative sensing during the sensing period prior to energy detection The results of simulations indicatethat in both cases there is a significant improvement in spectrum sensing performance in comparison withthe conventional energy detection Denoising of received signal by wavelet transform method indicatesbetter performance in comparison with the received signal transition through the filter matching on thesquare root of the signal spectrum Keywords Cognitive radio spectrum sensing energy detection non gaussian noise wavelettransform primary power spectrum

عليمحمد دوست حسيني

سعيد صدري