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799 results on '"Xu, Zhengyuan"'

152. Asymptotic performance of subspace methods for synchronous multirate CDMA systems

Author

Xu, Zhengyuan

Subjects
Signal processing -- Research, Asymptotic distribution (Probability theory) -- Research, Digital signal processor, Code Division Multiple Access technology, Business, Computers, Electronics, Electronics and electrical industries
Abstract

A multirate code division multiple access (CDMA) system, with either multicode or multiple processing gain access, is investigated. The subspace method is generalized in order to estimate multipath parameters by taking into account projections of signature waveforms of all symbols from the desired user onto the noise subspace. more...

Published
2002

162. Low-complexity multiuser channel estimation with aperiodic spreading codes

Author

Xu, Zhengyuan

Subjects
Signal processing -- Research, Correlation (Statistics) -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Precomputing deterministic code-related quantities is employed to obtain low complexity in multiuser channel estimation. Unknown multipath parameters are estimated based on correlation matching.

Published
2001

163. Asymptotically near-optimal blind estimation of multipath CDMA channels

Author

Xu, Zhengyuan

Subjects
Signal processing -- Research, Correlation (Statistics) -- Research, Wireless communication systems -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Weighted correlation-matching methods are used to estimate multipath channel parameters in a multiuser code division multiple access (CDMA) system. The weighting matrix can be arbitrarily chosen but must be positive definite. more...

Published
2001

185. Multi-Criterion Attribute Reduction Based on Fuzzy Rough Set Models

Author

Xu Zhengyuan, Zhu Yue, and Wen Huixiang

Subjects
Decision error, Computer science, Word error rate, Data mining, Fuzzy rough sets, computer.software_genre, Classifier (UML), computer, Fuzzy logic
Abstract

Attribute reduction defined by decision error rate in fuzzy rough set model can improve the classification performance of fuzzy rough classifier by deleting redundant attributes, but such reduction does not consider the variations of classification results. To fill this gap, a multi-criterion attribute reduction method is proposed based on four kinds of fuzzy rough set models. This method takes into account both decision error rate and decision consistency. On the basis of the new attribute reduction algorithm, a heuristic algorithm is designed to derive the reduction algorithm. The goal of the algorithm is to obtain smaller error rate and higher consistency at the same time. The experimental results on 4 UCI datasets show that the reducts based on multi-criteria can not only effectively improve the classification accuracies, but also achieve high decision consistencies. more...

Published
2019
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186. Performance analysis of minimum variance CDMA receivers

Author

Tsatsanis, Michail K. and Xu, Zhengyuan

Subjects
Signal detection (Electronics) -- Research, Spread spectrum communications -- Research, Mathematical optimization -- Usage, Wireless communication systems -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

A framework for providing solutions to constrained optimization of the code division multiple access (CDMA) receiver's variance was developed focusing on maximum signal energy that utilized all delayed copies of the signal of interest. CDMA systems are significant in the development of wireless communication devices employing receivers that suppress multiuser interference. It was discovered that the choice of the constraint vector affected the performance of constrained minimum variance CDMA receivers. more...

Published
1998

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