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تاثير اللاخطية في الالياف البصرية على اداء نظام تجميع الاطوال الموجية الضوئية المنقسمة باستخدام تقنية الاستقطاب المزدوج لتقسيمات التردد المتعامد الضوئي == Effect of Fiber Nonlinearity On The Performance of WDM Optical Systems Using Dual Polarization CO - OFDM Technique

اسم المؤلف: بشار مظفر احمد
اسم المشرف: رعد سامي فياض
الموضوع العام: هندسة الكهرباء والالكترون والاتصالات
السنة: 2014
الموضوع الدقيق: هندسة الالكترونيك والاتصالات
الدرجة: ماجستير
الجامعة: جامعة النهرين - كلية الهندسة - قسم الهندسة الالكترونية والاتصالات
اللغة: الانكليزية
مكان الجامعة: بغداد
الصفحات الاولى:
المستخلص: The implemented existing high capacity optical networks are based on 50 GHz wavelength - division multiplexing (WDM) channel spacing and carry up to 50 Gb/s data rate per channel. In recent years, there is increasing interest in using dual - polarization (DP) technique to enable future systems with at least 100 Gb/s rate per channel to operate over existing optical networks. The performance of these advanced systems can be enhanced further by using coherent optical orthogonal frequency division multiplexing (CO - OFDM) technique which offers high spectral efficiency and outstanding tolerance of fiber dispersion.This thesis addresses the effect of fiber nonlinear optics on the performance of dual polarization CO - OFDM/WDM system operating with 100 Gb/s per channel. Different modulation formats, namely BPSK, QPSK and 16 - QAM, are used. First, the performance of a single - channel system is investigated in the absence and presence of fiber nonlinearity. The results are compared with those of a conventional (single - polarization) system to identify the key role played by the DP technique. The investigation is then extended to WDM systems incorporating DP - OFDM technique. The results reveal that the effect of fiber nonlinearity can be reduced or cancelled by using optimum transmitter laser power Popt. Further, the value of Popt is a function of transmission distance,number of multiplexed channels, and modulation formats. Popt of - 11, - 12, and - 5 dBm is needed for a ten - channel DP system operating with BPSK, QPSK, and 16 - QAM formats, respectively.Simulation results presented in this thesis are obtained using OptiSystem (version 11.1) which is a commercial software package.

الغاء تداخل المسا ارت التخميني في انظمة الوصول المتعدد باستخدام تقسيم الترميز الواسع الطيف لشبكات الاتصال اللاسلكية == Multipath Interference Cancellation Investigation In Wcdma Communication Networks

اسم المؤلف: نور محمد خليل
اسم المشرف: منال جميل الكندي
الموضوع العام: هندسة الكهرباء والالكترون والاتصالات
السنة: 2014
الموضوع الدقيق: هندسة الالكترونيك والاتصالات
الدرجة: ماجستير
الجامعة: جامعة النهرين - كلية الهندسة - قسم الهندسة الالكترونية والاتصالات
اللغة: الانكليزية
مكان الجامعة: بغداد
الصفحات الاولى:
المستخلص: Bit Error Rate (BER) and Bit Energy to Noise Ratio(?????????) performance of the 1 - D RAKE receiver without , with Space Time Transmit Diversity (STTD) and 2 - D RAKE without , with (STTD) and also without and with beamforming for WCDMA over RayleighChannel in presence of Additive White Gaussian Noise (AWGN) channel is demonstrated with purpose of making simulation of m - files developed in Matlab.Results are evaluated in terms of BER and ????????? considering the number of Base Station (BS) transmit antennas (1 - D RAKE and 2 - D RAKE receivers), and the number of RAKE fingers (1 - D RAKE receiver) and the number of Mobile Station (MS) receive antennas (2 - DRAKE receiver). The performance results of 1 - D RAKE and 2 - D RAKE receivers showed that the receivers have satisfactory BER performance and the performance of RAKE receivers is more improved by increasing the number of RAKE fingers, performance is even better when beamforming was applied.The performance results of the three receive diversity of 2 - D RAKE receiver schemes : Selection Combining (SC), Equal Gain Combining (EGC) or Maximal Ratio Combining (MRC)) of 2 - D RAKE showed that there are significant improvements in BER and ?????????performance over the 1 - D RAKE. BER of 10???? can be obtained at ????????? ? 5 dB performance with four fingers of 2 - D RAKE receiver with STTD and beamforming and MRC scheme for five receive antenna elements.

تحسين جودة الصورة التوموغرافية المعاد تركيبها باستخدام خوارزمية التسقيط العكسي المرشحة == Enhancement of Tomographic Image Quality Reconstructed By Filter Backprojection Technique

اسم المؤلف: دعاء نوفل حازم
اسم المشرف: محمد حسين الحياني
الموضوع العام: هندسة الكهرباء والالكترون والاتصالات
السنة: 2014
الموضوع الدقيق: هندسة الالكترونيك والاتصالات
الدرجة: ماجستير
الجامعة: جامعة النهرين - كلية الهندسة - قسم الهندسة الالكترونية والاتصالات
اللغة: الانكليزية
مكان الجامعة: بغداد
الصفحات الاولى:
المستخلص: Computed tomography refers to the imaging of slices of an object by exposing them to X - ray in different directions. Measurement of image quality is one of great importance in the field of medical applications. In applications such as CT and MRI scanning, most of the time the quality of reconstructed image is assessed qualitatively by radiologist or domain experts which are purely subjective evaluation.The FBP algorithm produces excellent quality and high performance reconstruction compared with other reconstruction algorithms. This thesis presents different projection types (fan beam geometry, and cone beam geometry) for the image reconstruction, the geometries are calculated analytically by specified 2D head phantom for fan beam and 3D head phantom for single slice spiral cone beam geometry with different ranges covering angle.In the thesis the FBP algorithm was applied with the fan beam and single slice geometries. Different types of filters (Hann, Hamming, Kaiser, Cosine, Ram - Lak, and Gaussian) are used in the algorithm and a new window filter is proposed in the algorithm. Comparisons are made between the new window and different common windows by quality measurement to get a reconstructed image with high quality and high performance suitable for the implementation of the FBP.A computer programs has been designed, written, and implemented in this work using MATLAB 7.1, for fan beam and single slice projections. Good results of quality and performance were obtained for the tomographic reconstructed image from its projection on CT scanner.
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