البحث — المستودع الرقمي العراقي

المستخلص: ترميز التحويل لوبي) هو نوع من الترميز النافوري يعمل بدون اي معلومات عن القناة. في هذا العمل، تم تصميم LT code)) باستخدام ماتلاب، التصميم يتكون من ثلاثة اجزاء ( Encoder ,Decoder, channel ). في الجزء الخاص بتصميم الـ (Channel ) استخدمنا (( flat fading ch | Luby transform code (LT Code) is a type of fountain codes operating without any information about channel. In this work, LT code design of LT code implemented by using Mat lab as simulation software, our design consists of three parts (encoder, channel and decoder). In the channel design, flat fading channel will be used as a noisy channel to measure the performance of LT code over this type of channels. From the result obtained, SNR improvement by (30dB) at (BER=?10?^( - 4)) compared with data effect by the fading channel without coding with BPSK modulation model under different values of degree of distribution (d). Other type of modulation model (QPSK) used to measure the effect of changing the modulation type on the code performance. From the results obtained, SNR improvement by (31dB) at (BER=?10?^( - 4)) compared with data effect by the fading channel without coding. The degree of distribution (d) is a critical point of design, two types of distribution presented in this work, robust soliton distribution (RSD) and ideal soliton distribution (ISD). (ISD) works poorly in practice, (RSD) is a practical way used to get the degree of distribution in design by adding two extra parameters (c and ? ) which provide the spike element (k/R) in high degree distribution to ensure the continued of decoding process. As a result obtained the value of (c) has a major effect on the spike position on high degree (c=0.15,k/R=10 and c=0.2,k/R=7) with selective value of ?=0.5.The successful decoding probability for two types of degree distribution is very important, the value of successful decoding probability for (ISD) for low number of encoding packets (50 - 100) packet is greater than the value of successful decoding probability for (RSD). In the high number of encoding packets (>150) the value of successful decoding probability for (RSD) is greater than the value of successful decoding probability for (ISD).Encoding time for two type of distribution also discussed in this work, based on the results obtained the encoding packets time when using (RSD) is less than the encoding packets time when using (ISD).

تقليل التاثيرات اللاخطية في منظومات التقسيم المتعدد للطول الموجي العالية الكثافة == Mitigation of Fiber Nonlinearity Effects In Ultra High - Dence WDM System

اسم المؤلف: سيف حسام عبد الواحد

اسم المشرف: علي يوسف فتاح

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الاتصالات

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: The optical signal is severely degraded when transmitted in the fiber due to both the linear and nonlinear distortions. It is well known that, the linear distortions in single mode fiber include chromatic dispersion (CD) and polarization - mode dispersion (PMD) while self - phase modulation (SPM), cross phase modulation (XPM) and four - wave mixing (FWM) are considered the most among nonlinear distortions. To deal with the nonlinear impairments, a number of techniques, such as electronic equalization, pre - coding, digital back - propagation(BP), pre - chirping, optical phase conjugation (OPC) and nonlinearity management, are developed and improved. In the present work, a method called Fractional Fourier Transform (FRFT) has been applied to mitigate fiber nonlinearity impairments. The Fractional Fourier Transform is a time - frequency distribution and an extension of the classical Fourier transform. Time domain FRFT can be implemented by using time lens according to the optical time - space duality theory. The modulated optical pulses will be pre - distorted by an FRFT module before being launched into fiber links. In this work, 10 Gb/s optical fiber system with five spans, each of length 60 Km, for three types of modulation formats (Return - to - Zero Differential Phase Shift Keying (RZ - DPSK), Return - to - Zero Differential Quaternary Phase Shift Keying (RZ - DQPSK) and Carrier - Suppressed Return - to - Zero (CSRZ)), single and multi - channel transmission systems are designed and simulated using “OptiSystem (2011) version 10.0” software package. In order to analyze the transmission performance of the simulated systems without and with FRFT, a set of eye diagrams, optical spectrum visualizers, Q - factor versus input power and Bite Error Rate (BER) versus Signal to Noise Ratio (SNR) curves are presented to evaluate the influence of FRFTon the system performance. For CSRZ modulation format the Q - factor for single channel system at 0 dBm (input power) was 43.5 without FRFT and 78 with FRFT. The BER of sixteen channel system (channel No.8) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 50 GHz at SNR 10 dB without FRFT is 10 - 4.8 and 10 - 7.4 with FRFT. The BER of thirty two channel system (channel No.16) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 50 GHz at SNR 10 dB without FRFT is 10 - 4.6 and 10 - 6.4 with FRFT. The BER of thirty two channel system (channel No.16) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 25 GHz at SNR 10 dB without FRFT is 10 - 2.56 and 10 - 3.24 with FRFT.

خوارزمية جديدة لنظام اخفاء المعلومات == New Algorithm For A Steganography System

اسم المؤلف: مروة جليل محسن

اسم المشرف: اثير علاء صبري

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الاتصالات

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: This thesis presents a new steganographic algorithm for embedding encrypted secret image in grayscale and color images to provide high level security of data for communication over unsecured channels.The proposed algorithm combine the features of Cryptography and Steganography. The hidden secret message capacity, stego - image quality and security are three important conditions for data hiding technology. According to these requirements, an effective security protection with high hiding capacity steganographic algorithms are proposed based on frequency domain of the cover and the secret image.The proposed algorithm first analyzes the secret image into its frequency components using Discrete wavelet transform (DWT) , Wavelet packet transform(WPT) , Multiwavelet transform(MWT) , and slantlet transform(SLT) , respectively. Then the low frequencycomponent of the secret image is encrypted using Advanced encrypted standard (AES) method and then embedded in the insensitive mid and high sub - bands obtained from the cover image after applying these transformations (mentioned earlier) on it. The embedding method used in this thesis is LSB (Least significant bit ) method. The resulting stego image from different algorithms are then compared..The effectiveness of the proposed algorithm has been estimated by computing Mean square error (MSE) ,signal to noise ratio (SNR), Peak Signal to Noise Ratio (PSNR) and the capacity.The best algorithm is obtained by using 2level - DWT for cover image and 1level - DWT or WPT for secret image because the capacity of the hidden secret data and stego image quality are improved. The embedding image reaches to half the size of cover image at same time PSNR reach to 62 dB and MSE about 0.036 and this is better than many other existence algorithms.By both objective and subjective observations, the resultant stegoimage that will be transmitted does not draw any suspicion, so the main goal of steganography is achieved..The language used for testing the algorithms is MATLAB R2013a, with a computer of the following specification ; Processor : Intel(R) Core(TM) i5 CPU M430 @ 2.27GHz and RAM - 3GBytes.

اخفاء العلامة المائية الرقمية باستخدام تحويل الموجيات ذات عامل جودة قابل للتعديل == Digital Watermarking Based On Tunable Q - Wavelet Transform

اسم المؤلف: هاجر احمد ابراهيم

اسم المشرف: اثير علاء صبري

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الاتصالات

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: لقد دخلنا عصر حيث المعدات غير المكلفة متوفرة ويمكن من خلالها انتاج نسخ كاملة من المواد المتعددة الوسائط الرقمية مثل صوتيات بجودة القرص المضغوط ونشر صور عالية الجودة او مقاطع الفيديو الرقمية. من خلال هذه البيئة اصبح من السهل على الجهات غير المختصة انتاج ن | We have entered an era where inexpensive and readily available equipment can produce perfect copies of digital multimedia materials, such as CD - quality audio, publication - quality images, or digital video. In this environment, it has become easier for malicious parties to make salable copies of copyrighted content without compensation to the content owner.Many media content owners are concerned about the potential loss of revenue from multimedia piracy, especially when the content will be exposed to the Internet. Digital watermarking is seen by many as a potential solution to this problem.In this thesis, two proposed methods one for grayscale image watermarking and the other for color image watermarking are suggested. They require the original image for watermark extraction and they are belonging to the wavelet domain watermarking. They exploit the Tunable Q_Wavelet Transform. Therefore, different cases are performed to identify the best among them for the proposed application. As a result of the testing process, the best case is founded when ( Q=4, r=8, J=28). The first proposed method can be used with applications requiring high degree of imperceptibility and high security. The embedding process of this method is based on adding the pseudorandom watermark bits in the largest TQWT coefficient.The second proposed method is more robust against distortions than the first proposed method and is characterized by an acceptable degree of imperceptibility and high security. The embedding process of this method is based on adding the compound watermark image to the original color image.They are performed using MATLAB7 programming language. Different images are tested and the watermark is extracted exactly from the watermarked images.The Peak Signal to Noise Ratio “PSNR” using best case for the two proposed methods is found (77.97) dB for the first method and (51.14) dB for the second method.

تعزيز اداء اتصالات الراديو عبر الليف احادي ومتعدد الطول الموجي بواسطة تقنية التضمين == Performance Enhancements of Single And Multi - Wavelength Radio Links Over Fiber By Modulation Technique

اسم المؤلف: مصطفى عبد الهادي جليل

اسم المشرف: عايد خلف محمد

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الاتصالات

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: تم تطوير تكنولوجيا الراديو عبر الالياف منذ اواخر القرن العشرين، وتم استخدامها في مجموعة من التطبيقات لانظمة الاتصالات ويعتبر الراديو عبر الالياف هو الجيل المقبل من انظمة الاتصالات لما يمتاز به من العديد من المزايا مقارنة مع النظام التقليدي مع توهين منخفض | Radio - over - Fiber (RoF) technology has been developed since the late 20th century and has been used efficiently in a range of applications for communication systems. Radio over fiber system is the next generation of communication systems because it has many advantages compared with conventional system with low attenuation, enormous bandwidth of optical fiber, and extension of existing coverage and capacity. RoF system refers to the radio signals which are modulated with optical signal and transmitted over optical fiber link from Central Office (CO) to the Remote Nodes (RNs).In this work, several RoF systems have been designed and simulated with different modulation techniques using commercial software package called “Optisystem v.12”. Furthermore, these systems were compared with each other to check for better performance. These systems are presented as follows : The first system is RoF with Quadrature Phase Shift Keying (QPSK), 16 - Quadrature Amplitude Modulation (16 - QAM), and 64 - QAM schemes with and without OFDM technique. The simulation results of this system show that the Signal to Noise Ratio (SNR) for 64 - QAM - OFDM higher than SNR for QPSK, 4 - QAM and 16 - QAM with OFDM at 10 - 9 symbol error, after 50 km of SMF length without any amplification or compensation techniques. In addition, also SNR for 64 - QAM - OFDM higher than SNR for other techniques in this work after 160 km of fiber length.The second system is the RoF with QPSK and 16 - QAM schemes with Digital Signal Processing (DSP) unit in the receiver side. The simulation results of this system show that the Error Vector Magnitude (EVM) for QPSK scheme with DSP unit is 14.5% and 85.5% without DSP unit after 50 km of fiber length. Furthermore, the EVM for 16 - QAM with DSP unit is 7.5%, but the EVM for the same system without DSP unit is 91%. In addition, the EVM for QPSK with DSP equal to 11.5%, but the EVM for 16 - QAM with DSP equal to 9% after 160 km of fiber length.The third system is RoF system with two multiplexing techniques, 8×10 Gbps WDM - RoF system and 4×5 Gbps SCM - RoF system, have been simulated with 4 - QAM - OFDM, 16 - QAM - OFDM and 64 - QAM - OFDM schemes. The fourth system was to combine the techniques of wavelength division multiplexing (WDM) and subcarrier multiplexing (SCM) to increase the capacity of the system by 20×8 Gbps data rate. The simulation results show that the SCM - WDM - RoF with 64 - QAM gives high SNR compared with SCM - WDM - RoF system with other modulation schemes which have been used in this work.