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IEEE Wireless Communications and Networking Conference

作者： Fujino, Yosuke Uchida, Daisei Fujita, Takafumi Kagami, Osamu Watanabe, Kazuji NTT Corp NTT Network Innovat Labs Yokosuka Kanagawa 2390847 Japan

ISBN: (纸本)9781424406586

The Multi-Target constant modulus algorithm (MT-CMA) can blindly separate multiple co-channel signals captured by an antenna array. It sequentially calculates the unknown weight vectors by executing CMA on a subspace spanned by these vectors, and estimates the weight vectors of all users. Thus, it needs to precisely estimate the subspace by using the calculated weight vectors. The conventional estimation method is to estimate the subspace assuming that the array output signals are orthogonal. However, when the Signal-to-Noise Ratio (SNR) is low, the subspace estimation accuracy is degraded due to the failure of orthogonality. To overcome this problem, we propose a new subspace estimation method for MT-CMA. It estimates the subspace by using eigen-value decomposition of the received signals' covariance matrix, which is independent of signal orthogonality. Computer simulation results show that the proposed algorithm achieves a 10% improvement of user capacity or 5.0dB improvement in required CNR. Moreover, the BER performance of the proposed algorithm is close to that of MMSE.

关键词： blind beamforming adaptive array multi-target array constant modulus algorithm

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Concurrent constant modulus algorithm and decision directed scheme for synchronous DS-CDMA equalisation

Concurrent constant modulus algorithm and decision directed ...

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13th IEEE Workshop on Statistical Signal Processing

作者： Hadef, Mahmoud Weiss, Stephan Univ South Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

ISBN: (纸本)0780394038

In this paper, we derive a concurrent constant modulus algorithm (CMA) and decision directed (DD) scheme for blind multiuser equalisation, suitable for downlink DS-CDMA systems. Adaptation is performed by concurrently minimising two cost functions based on either a CM criterion or a DD scheme for all active users. Computer simulations are used to assess the performance of the algorithm.

关键词： constant modulus algorithm decision directed adaptation downlink DS-CDMA system FIRMER-CMA

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Fast convergent multiuser constant modulus algorithm for use in multiuser DS-CDMA environment

Fast convergent multiuser constant modulus algorithm for use...

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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Arasaratnam, P Zhu, S constantinides, AG Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn Commun & Signal Proc Grp London SW7 2BT England

ISBN: (纸本)0780374029

In a multi-user direct sequence code division multiple access (DS-CDMA) system, retrieval of the transmitted signals with a conventional receiver is difficult when there is chip asynchronism, multipath propagation and the associated near-far problem. The results show that despite these problems an adaptive linear receiver based on a mixed cross correlation and constant modulus algorithm (CC-CMA) has the potential to retrieve all users simultaneously. In this paper, we propose several algorithms based on Quasi-Newton type algorithms. Compared with the conventional CC-CMA algorithm, the proposed algorithms achieve faster convergence at low computational cost. Simulations support the improved convergence properties of the algorithm.

关键词： convergence of numerical methods multiuser channels code division multiple access spread spectrum communication multipath channels radio receivers correlation methods Newton method constant modulus algorithm multiuser DS-CDMA direct sequence code division multiple access chip asynchronism multipath propagation near-far problem adaptive linear receiver cross correlation algorithm convergence

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Property of the constant modulus algorithm to Capture the Weak Signal

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The Journal of China Universities of Posts and Telecommunications 2003年第1期10卷 9-14页

作者： LINing GUOYan GUOLi InsituteofSciences PLAUST.Nanjing210007P.R.China SchoolofInformationEngineering BeijingUniversityofPostsandTelecommuncationsBeijing100876P.R.China

The constant modulus algorithm (CMA) enjoys widespread popularity as methodsfor blind beamform-ing and equalization of communication signals, CMA is straightforward toimplement, robust, and computationally of moderate complexity. Furthermore, it is insensitive toarray imperfection. In an environment containing multiple constant modulus signals, the signalextracted by CMA depends on the relative power of the incident signals. According previous works,the CMA is prone to capture the strongest constant modulus (CM) signal at the output of the *** this paper, we show that the weak CM signal could be recovered by CMA_(1-2) and CMA_(2-1) whensetting special step-size. Simulation examples confirm our remarks.

关键词： constant modulus algorithm step-size singular value decomposition

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Convergence behavior of the constant modulus algorithm controlled by special stepsize

Convergence behavior of the constant modulus algorithm contr...

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6th International Conference on Signal Processing

作者： Guo, L Li, N Guo, Y Zhou, JP BUPT Sch Informat Engn Beijing 100876 Peoples R China

ISBN: (纸本)0780374886

The constant modulus algorithm (CMA)enjoys widespread popularity as methods for blind beamforming and equalization of communication signals. CMA is straightforward to implement, robust, and computationally of modest complexity. Despite its effectiveness and apparent simplicity, adaptive implementation of the CMA comes along with several complicating factors that have never really been solved. In particular, convergence can be unpredictable and slow depending on the stepsize. In this paper, Convergence behaviors of the constant modulus algorithm based on "1-2" cost, function (CMA(1-2)) and "2-1" cost function (CMA(2-1)) are investigated. We found that certain signal could be quickly removed from the output data choosing special stepsize if at least two signals were with different power. Simulation examples confirm the results.

关键词： constant modulus algorithm stepsize singular value decomposition

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constant modulus algorithm and subspace approach for blind fractionally spaced equalization

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Xitong Fangzhen Xuebao / Journal of System Simulation 2005年第2期17卷 304-307页

作者： Wang, Yong-Chuan Chen, Zi-Li Liu, Zeng-Tian Dept. of Optical and Electron. Eng. Ordnance Engineering Coll. Shijiazhuang 050003 China

The constant modulus algorithm (CMA) and subspace approach are both blind algorithms, which are applied in the communication signal processing widely. We combine the CMA with the subspace approach and propose the CM_SUB blind equalization algorithm. Simulation results show that the proposed CM_SUB algorithm is superior to the traditional CMA algorithm on convergence rate.

关键词： Blind fractionally spaced equalization constant modulus algorithm Subspace approach Wireless channels

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ADAPTIVE STEP-SIZE constant modulus algorithm FOR BLIND MULTIUSER DETECTION IN DS-CDMA SYSTEMS

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Journal of Electronics(China) 2004年第1期21卷 10-15页

作者： SunLiping HuGuangrui Dept.ofElectronicEng. ShanghaiJiaotongUniv.Shanghai200030

Blind Adaptive Step-size constant modulus algorithm (AS-CMA) for multiuser detection in DS-CDMA systems is presented. It combines the CMA and the concept of variable step-size, uses a second LMS algorithm for the step size. It adjusts the step-size according to the minimum output-energy principle within a specified range, thus overcomes the problems of bad effect of fixed step-size LMS algorithm. Compared with Adaptive Step-size LMS (AS-LMS) algoritilrn, through simulations, this algorithm can adapt the changes of the environment, suppress multiple access interference in the dynamic environment and the stability of Signal to Interference Ratio (SIR) is superior to that of AS-LMS.

关键词： CDMA constant modulus algorithm Blind interference suppression

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Convergence Behavior of the constant modulus algorithm Controlled by Special Stepsize

Convergence Behavior of the Constant Modulus Algorithm Contr...

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2002年第6届信号处理国际会议

作者： Guo Li Li Ning Guo Yan Zhou Jiongpan (School of Information Engineering, BUPT, Beijing, 100876, China) (Institute of Science, PLAUST, Nanjing 210016, China)

The constant modulus algorithm (CMA) enjoys widespread popularity as methods for blind beamforming and equalization of communication signals. CMA is straightforward to implement, robust, and computationally of modest complexity. Despite its effectiveness and apparent simplicity, adaptive implementation of the CMA comes along with several complicating factors that have never really been solved. In particular, convergence can be unpredictable and slow depending on the stepsize. In this paper, Convergence behaviors of the constant modulus algorithm based on "1-2" cost function (CMA1-2) and "2-1" cost function (CMA2-1) are investigated. We found that certain signal could be quickly removed from the output data choosing special stepsize if at least two signals were with different power. Simulation examples confirm the results.

关键词： constant modulus algorithm stepsize singular value decomposition

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FAST constant modulus ADAPTIVE algorithm

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IEE PROCEEDINGS-F RADAR AND SIGNAL PROCESSING 1991年第4期138卷 379-387页

作者： BENESTY, J DUHAMEL, P PAB/RPE Centre National d'Études des Télécommunications Paris France

An exact block formulation of the constant modulus algorithm (CMA) is presented, in which a reduction of arithmetic complexity is achieved. Two types of fast algorithms are explained, either in time-domain or in frequency-domain. The first one is of greater interest for small block lengths and the second one, using the FFT as an intermediate step, has greater advantage for large blocks. Due to the equivalence between the original CMA formulation and this one, the convergence properties of the CMA are maintained, which is not the case in the Treichler et al. implementation in frequency domain of this algorithm. Furthermore, this approach allows the use of very small block lengths (e.g. N = 2), the reduction of the arithmetic complexity increasing with the block size.

关键词： algorithmS constant modulus algorithm

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Series Equalizer Based on constant modulus algorithm and Decision-directed algorithm

Series Equalizer Based on Constant Modulus Algorithm and Dec...

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2009 Asia-Pacific Conference on Information Processing

作者： Wei Rao,Jian-bing Liu,Yuan-yuan Liu,Wen-qun Tan,Hui-jun Xu,Kang-ming Yuan,Guo-xing Dai Nanchang Institute of Technology Nanchang,330099,China

A new series equalizer based on constant modulus algorithm(CMA) and Decision-directed(DD) algorithm is proposed to overcome Inter-Symbol Inter-ference(ISI) much better in the communication system without the aid of training *** proposed equalizer uses the CMA as the forward filter and DD algorithm as the back *** two filters are series and operate *** makes full use of the advantages of the CMA's "eye-opened" ability and DD's superior convergence *** the proposed equalizer obtains not only the faster convergence and lower residual error but also the ability of phase *** simulations with underwater acoustic channels are presented and the simulation results are shown to prove the efficiency of the proposed equalizer.

关键词： seriers equalizer constant modulus algorithm decision-directed algorithm underwater acoustic channel

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