ADAPTIVE ANTENNA ARRAY ALGORITHMS AND THEIR IMPACT ON CODE DIVISION MULTIPLE ACCESS SYSTEMS (CDMA)

Abstract

In mobile communications there is a need to

increase the channel capacity. The increasing

demand for mobile communication services without

a corresponding increase in RF spectrum allocation

(channel capacity) motivates the need for new

techniques to improve spectrum utilization. The

CDMA and adaptive antenna array are two

approaches that shows real promise for increasing

spectrum efficiency. This paper focuses on the

application of adaptive arrays to the Code Division

Multiple Access (CDMA) cellular systems. The

adaptive antenna has an intelligent control unit, so

the antenna canfollow the user, direct the radiation

pattern towards the desired user, adapt to varying

channel conditions and minimize the interference.

Therefore there can be several users in the same

channel in the same cell. The driving force of this

intelligent control unit are special kinds of

algorithms and we are going to investigate the

performance of these different adaptive array

algorithms in the CDMA systems

In this paper four each blind adaptive array

algorithms are developed, and their performance

under different test situations (e. g. A WGN (Additive

White Gaussian Noise) channel, and multipath

environment) is studied A MATLAB test bed is

created to show their performance on these two test

situations and an optimum one can be selected We

shall also try to show the adaptive nature of the

beam former in response to the change in the

direction of arrival of the signal on the antenna

array. The matlab program will plot a rectangular

and polar plot for the signals of different users