الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
FSO has attracted attentions because of its advantages such as: Large bandwidth, license free spectrum, high data rate, easy, quick deploy ability and easy to establishment. There are three types of phenomenons that effects on FSO. Absorption, Scattering and Attenuation of the atmospheric channel. The most effective parameters is turbulence that can make BER (bit error rate) decreased and link of communication unseen. The Optical Wireless Communications(OWC) technology have many advantages and applications: Ultra-short range, Short range, Wireless Personal Area Network (WPAN), Medium range, Long range, Ultra-long range and deep space links. FSO technology has a lot of uses nowadays,I used FSO in outdoor environment and explain the effect of parameters of weather conditions such as :(fog, haze,rain) using a model of log normal distribution in a standard wavelength 1550 nm. Numerical simulations show that the pointing errors up to 10 μrad and bad weather conditions up to 15 dB attenuation have effects on the system performance and we should use digital signal processing and equalization to enhance it. In this thesis, there are six chapters which are arranged as: Chapter 1 discusses a general introduction of the thesis. Chapter 2 introduces the literature review of FSO technology and the different modulation techniques. Chapter 3 explains and discuses a different channel models and parameters that effects such as Geometric and Misalignment Losses. introduces the methods for performance enhancement of FSO and the different types of Modulation techniques and a comparative study in terms of their probability of errors. Chapter 5 illustrates system Proposal using different techniques Log-normal distribution of optical QPSK over FSO system. Chapter 6 concludes the results and suggestions of this study with reporting some suggested future work.