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تصميم ومحاكاة نظام اتصالات امن يرتكز على النظام الفوضوي عبر قناة كاوس الضوضائية == Design And Simulation Of Secure Communication System Based On Chaos Over AWGN Channel
Author name:
امير كاظم جواد
Supervisor name:
حكمت نجم عبد الله | سعد سفاح حسون
General topic:
Electrical, Electronic and Communications Engineering
Specific topic:
Electrical and Electronic Engineering
Degree:
Master
University:
Mustansiriyah University - College Of Engineering - Department Of Electrical Engineering
Language:
English
University location:
Baghdad
First pages:
34T518 - p.pdf
Abstract:
مع زيادة التطور الكبير الذي يحصل في علم الاتصالات ومع وجود قناة عامة (public channel) تنتقل من خلالها المعلومات زادت المشاكل التي تخص القناة وبالخصوص مشكلتين رئيسيتين هما انتهاك الخصوصية ووجود الضوضاء. بخصوص امنية الاتصال : بما ان القناة عامة وبامكان اي م | With the significant development in communication systems especially with the public channel through which information travels, there are increasing in the channels problems. Among these problems, the two important should be addressed are the information security and the noise. In this thesis, an efficient communication system with high security and high immunity against noise has been proposed. From security perspective, the proposed scheme uses two levels of encryption based on chaotic systems. The first level is chaotic scrambling, while the second level is chaotic masking. Two levels of chaos based encryption make information very secure during their transition in the channel because the key space becomes too large. The simulation results show that the Segmental Spectral Signal to Noise Ratio (SSSNR) of the first level (chaotic scrambling) is reduced by - 5.195 dB in comparison with time domain scrambling. In the second level (chaotic masking), the SSSNR is reduced by - 20.679 dB. It is also show that when the two levels are combined, the overall reduction obtained is - 21.755 dB.Concerning the immunity against noise, the proposed system offers three methods to reduce the effect of noise. The first method is based on sending each scrambled sample more than once. The simulation results showed that gain of this method is 10 dB if we send each voice sample 8 times over the classical method without repetition. The second method relies on the conversion of information from analog to digital format before doing the masking. The simulation results of this method show that the mean square error (MSE) is reduced and this reduction increases as signal to noise ratio (SNR) increase. For instance when SNR=10 dB, the MSE is reduced from ?10?^( - 1) to 2*?10?^( - 2) while it reduced from ?10?^( - 2) to 3*?10?^( - 6) when SNR=22 dB. The third method is increasing the power of the information signal relative to chaotic signal. The simulation results show that when the power is duplicated and at SNR = 24 dB, the MSE is reduced from 3*?10?^( - 3) to 0.5*?10?^( - 4) and to 3*?10?^( - 5) when the signal power is tripled.
