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AN IMPROVED WINDOW BLOCK CORRELATION ALGORITHM FOR CODE TRACKING IN W-CDMA
تحسين خوارزمية تتبع كتلة النافذة لتعقب الشفرة في نظام الحزمة الواسعة

Author: Hassan A. Nasir حسن عباس ناصر
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2012 Volume: 5 Issue: 4 Pages: 367-376
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

Wide-Band Code Division Multiple Access (W-CDMA) is designed to offer more flexible wide band service which cannot implement by all the current cellular systems. The performance of a W-CDMA is limited by the synchronous transmission that users are creating between them during transfer the information, and a result of losing synchronous properties it becomes more difficult for the users to maintain reliable communication.In this paper, an algorithm is proposed in which improved the window block correlation tracking to solve this problem. That this mechanism depends on the system estimator to calculate the threshold of error in time and determine the value of the Power Delay Profile PDP at the point of synchronization by relying on guess the behavior of the PDP adaptively. Computer simulation tests are used to examine the performance of the proposed algorithm with different channel conditions, AWGN and user movement and the results show that it less complexity and faster in decision to get the synchronization as compared with the traditional algorithm.

تم تصميم نظام الحزمة الواسعة بالتقسيم الشفري المتعدد الوصول (W-CDMA) لتقديم خدمة أكثر مرونة, واسعة النطاق والتي لا يمكن تنفيذها من قبل جميع الأنظمة الخلوية الحالية. إن أداء W-CDMA يكون محدد بخاصية النقل المتزامن بين المستخدمين والتي يجرونها خلال نقل المعلومات بينهما ، ونتيجة لفقدان خاصية التزامن يصبح أكثر صعوبة بالنسبة للمستخدمين للحفاظ على اتصال حقيقي يمكن الاعتماد عليه.في هذا البحث، تم اقتراح خوارزمية تؤدي إلى تحسين طريقة تتبع كتلة النافذة (WBC) في مواجهة هذه المشكلة. إن هذه الآلية تعتمد على نظام تخمين لحساب عتبة الخطأ الزمني وتحديد PDP عند نقطة التزامن من خلال الاعتماد على التخمين في سلوك PDP دوريا. وتم اختبار الخوارزمية المقترحة ببرنامج محاكاة بالحاسوب لبيان أدائها تحت ظروف قناة متغيرة، AWGN وحركة المستخدم والنتائج أظهرت أنها أقل تعقيد وأسرع في قرار للحصول على التزامن، مقارنة مع الخوارزمية التقليدية.

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Article
Message Coding and Compression with Artificial Neural Networks

Authors: Hasan M. Azzawi --- Hassan A. Nasir --- Ali K. Naher
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 16 Pages: 3429-3437
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The need to overcome data preprocessing inherent in much of the classical data coding techniques commonly available led to the search for a free, easy-to-use, but flexible and powerful method. Artificial Neural networks have been attracting more and more researchers since the past decades. The distinct properties, such as learning ability,nonlinearity, fault tolerance, generalization etc., make it suitable for information protection, such as data encryption, data authentication, data detection, etc. In this paper a simple and low-cost coding method based on neural networks is proposed to be used to patterns compression. The goal of the developers is to build a tool able to store and send a coded and compressed message. The formed two-dimensional patterns are coded and compressed using the multilayer neural network with Back-propagation training algorithm. Hidden layer outputs of a trained network are sent as two-dimensional data,which represents the encoded vectors. To reconstruct the original patterns, this requires the output weights matrix and the output nodes functions which are unknown and not available in the encoded sent vectors. A compression rate of about 6:1 has been achieved.

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