Liping Zhu

Publication Date

1995

Document Type

Dissertation/Thesis

First Advisor

Tahernezhadi, Mansour

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering

LCSH

Code division multiple access; Adaptive control systems; Electric interference

Abstract

Multiple access (MA) interference leads to significant performance degradation in code division multiple access (CDMA) system. The MA interference is most severe when users have different power levels and/or when they transmit their signals asynchronously. The conventional matched-filter scheme cannot effectively suppress this kind of interference. Much effort has been made to develop a scheme that can suppress the severe MA interference. Among all different interference suppressing schemes, two minimum-mean-square-error (MMSE) based schemes, namely, N-tap scheme and D-tap cyclically shifted filter bank (CSFB) scheme, are studied. Both schemes require only modest computations and are amenable to adaptive implementations that do not require knowledge of the interference parameters such as relative strength and spreading sequences of the users. These two MA interference suppression schemes are implemented using several adaptive algorithms, namely, least mean square, gradient lattice and predictive least mean square. Their performance of suppressing the MA interference is evaluated using the bit-error-rate (BER) criterion as well as minimum-mean-square error (MMSE) criterion. Computer simulations are carried out to obtain the MSE and BER under various interference conditions. The results show that the N-tap scheme and D-tap CSFB scheme yield a much better performance than that of the matched-filter scheme.

Comments

Includes bibliographical references (pages [82]-85)

Extent

viii, 85 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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