الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Multimedia transmission through wireless networks suffers from many problems due to the involved high data rates and the corresponding fading, interference and coverage limitations. Third Generation (3G) and Fourth Generation (4G) wireless networks are designed to support high rate multimedia communications. In particular, World Interoperability for Microwave Access (WiMAX) and Long Term Evolution (L TE) and their most recent developments (IEEE 802.16e Mobile WiMAX and LTE-Advanced) are the most considered systems for future multimedia wireless communications. Multiple¬antenna techniques are used by these systems to improve the bit error rate (BER) performance, increase cell range, transmitted data rate through spatial multiplexing and interference reduction from other users. In this thesis we study the coverage and capacity limitations of these systems as well as proposing some enhancement techniques to improve their performance and increase their coverage capabilities. These techniques are simulated for the environment of the city of Alexandria, Egypt. In Mobile WiMAX systems (adopting cellular structure), users at the cell border suffer from poor Signal to Interference plus Noise Ratio (SINR) conditions due to the high amount of interference from neighboring cells. Therefore, the challenges facing coverage and its dependence on throughput for the Stanford University Interim (SUI) channel model performed at 3.5 GHz are discussed. This is done through statistical analysis and real-time simulation software to discover the effects of channel characteristics, channel model and forward error correction techniques when designing and planning a mobile WiMAX network. In addition, the performances of different Multiple-Input Multiple¬Output (MIMO) configurations adopted for mobile WiMAX are studied in detail. For Long Term Evolution Advanced (L TE-A) systems we simulate and analyze the use of advanced techniques including link adaptation (LA) with Open Loop Spatial Multiplexing (OLSM), Closed Loop Spatial Multiplexing (CLSM) and Space Time Coding (STC) for their performance improvement. The simulation results are compared with the theoretical values obtained using the known MIMO capacity mathematical models to figure out the most cost effective, low complexity and highest efficiency network structures that are suitable for the considered geographical location of city of Alexandria. In addition, a new technique to mitigate the inter-cell interference for cell edge users in LTE-A systems combining soft fractional frequency reuse with adaptive beamforming is introduced, analyzed and simulated. The results of the simulations show that this technique results in noticeable improvements in the cell throughput and the capacity of cell edge users. of this thesis have important application in planning and improving 4G wireless multimedia systems.