Modeling of Signal Fading Phenomena in Code Division Multiple Access System in Sudan

Abstract

Recent advances in wireless communication systems have increased the throughput over wireless channels and networks, at the same time; the reliability of wireless communication has been increased. A mobile signal propagation through wireless channel is a complicated phenomenon characterized by such problem as fading .A precise mathematical, description of this phenomenon is either unknown or too complex for tractable communication system analyses, however considerable efforts have been devoted to the statistical modeling and characterization of the different effects ,the result is a range of relatively simple and accurate statistical models of fading channels that depends on particular environmental propagation Some of the challenges in wireless communications are:- A need for high data rates, quality of service, mobility , portability, connectivity in wireless networks, interference from other users , (Fade),privacy/Security. This research shows how to calculate and put suitable parameters to solve the fade out of fading of the signals in mobile station, .Fading, is caused by:- 1- Reflection. – Propagating wave impinges on an object which is large compared to the wavelength– e.g., the surface of the Earth, buildings, walls, etc. 2- Diffraction. – Radio path between transmitter and receiver obstructed by surface with sharp irregular edges– Waves bend around the obstacle, even when the line of the site does not exist. 3- Scattering. – Objects smaller than the wavelength of the propagating wave– e.g., foliage, street signs, lamp posts. 4-The Speed of the mobile handset vi This Research aims to calculate and measure the fading uses of different statistical and model in this Research, allows for the graceful introduction of newer applications, thereby increasing the average revenue per user, in contract of network, Quality of Services provisioning in mobile network is more challenging primarily due to the fading and mobility which are most in corporate in the quality of services architectures designed for mobile network depend on the terrain, dealing with these parameters can cover the poor areas (out of range) without installing BTS.………………………etc. The primary goal of this research work is to identify the basic characteristics of CDMA, explore fundamental concepts of the fading parameters of wireless channels and the physical layer .This can be consider as contribution which can effectively used. This research also summarizes the types of fading caused by Doppler spread and Delay spread. Besides making simulation and analysis of results the concluded, the result can be used to design suitable network N.W to Sudan terrain, and make certain of the mobile quality on the communication range and adapted modulation with the fading channels, considering the improvement of the multiuser of mobile.