Development and Analysis of Adaptive Interference Rejection Techniques for Direct Sequence Code Division Multiple Access Systems

The inadequacy of conventional CDMA receivers in a multiple access interference-limited mobile radio environment has spurred research on advanced receiver technologies. This research investigates the use of adaptive receivers for single user demodulation to overcome some of the deficiencies of a conventional receiver and, hence, enhance the system capacity. Several new adaptive techniques are proposed. The new techniques and some existing schemes are analyzed. The limitation of existing blind algorithms in multipath channels is analyzed and a new blind algorithm is proposed that overcomes this limitation. The optimal receiver structure for multi-rate spread spectrum systems is derived and the performance of this receiver in various propagation channels is investigated. The application of coherent and differentially coherent implementations of the adaptive receiver in the presence of carrier frequency offsets is analyzed. The performance of several new adaptive receiver structures for frequency offset compensation is also studied in this research. Analysis of the minimum mean-squared error receiver is carried out to provide a better understanding of the dependence of its performance on channel parameters and to explain the near-far resilience of the receiver. Complex differentially coherent versions of the sign algorithm and the signed regressor algorithm, algorithms that have a much lower computational complexity than the least-means square algorithm, are proposed and applied for CDMA interference rejection.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1999

Author dc:creator

• Mangalvedhe, Nitin R.

Chair dc:contributor.committeechair

• Reed, Jeffrey H.

Committee members dc:contributor.committeemember

• Kobza, John E.
• Beex, A. A. Louis
• Woerner, Brian D.
• Tranter, William H.

• MMSE Analysis
• Interference Rejection
• Multiple Access Interference
• Adaptive Receivers
• Adaptation Algorithms
• Multi-Rate Systems
• CDMA Systems

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-072599-170513

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/28399