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Wireless sensing network transmission system with improved constant modulus algorithm

EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2013年第1期2013卷 1-8页

作者： Sung, Wen-Tsai Natl Chin Yi Univ Technol Dept Elect Engn Taichung 41170 Taiwan

To solve the instant signal convergence of wireless sensing network transmission system, this study proposes an improved constant modulus algorithm. The improved constant modulus algorithm can quickly find the convergent direction by adding error functions and learning rates based on the reserved original cost functions. After processed by a matched filter, the received consecutive time signal can be sampled in accordance with symbol interval or fraction interval, so that signal channels can be estimated or balanced. At last, this study verifies the raised method with quadrature amplitude modulation on wireless sensing network transmission system and improved constant modulus algorithm experiments which show that the learning rates and the performances of balancers are improved.

关键词： Wireless sensor network Transmission system constant modulus algorithm 4QAM

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Adaptive set membership constant modulus algorithm with a generalized sidelobe canceler based on dynamic bounds for beamforming

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SIGNAL PROCESSING 2014年 104卷 94-104页

作者： Cai, Yunlong de Lamare, Rodrigo C. Zhao, Minjian Zhejiang Univ Dept Informat Sci & Elect Engn Hangzhou 310027 Zhejiang Peoples R China Univ York Dept Elect Commun Res Grp York YO10 5DD N Yorkshire England CETUC PUC Rio BR-22453900 Rio De Janeiro Brazil

In this study, we propose an adaptive set membership constant modulus (SM-CM) algorithm with a generalized sidelobe canceler (GSC) structure for blind beamforming. We develop a stochastic gradient (SG) type algorithm based on the concept of SM filtering to facilitate an adaptive implementation. The filter weights are updated only if the constraint cannot be satisfied. In addition, we also propose an extension of two schemes of time-varying bounds for beamforming with a GSC structure where we incorporate parameter and interference dependency to characterize the environment, which improves the tracking performance of the proposed algorithm in dynamic scenarios. A convergence analysis of the proposed adaptive SM filtering technique was performed. The simulation results showed that the proposed adaptive SM-CM-GSC algorithm with dynamic bounds delivered superior performance compared with previously reported methods and at a reduced update rate. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Adaptive beamforming constant modulus algorithm Generalized sidelobe canceler Interference suppression Set-membership filtering

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Dynamically Partitioned Hierarchical constant modulus algorithm for Variable Delay Spread Channels

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WIRELESS PERSONAL COMMUNICATIONS 2012年第2期62卷 395-410页

作者： Woo, Tai-Kuo Natl Def Univ Dept Informat Management Taipei Taiwan

The constant modulus algorithm (CMA) adopts the constant modulus (CM) criterion to minimize the deviation of the equalizer output from a fixed value. However it has two drawbacks: (1) slow rate of convergence (2) the likelihood of getting trapped in a local minimum. The problem gets even worse when the channel delay spread varies rapidly as the filter length cannot match the delay spread. If the filter length is significantly longer than the delay spread, the convergence rate can be slow. In this paper, we improve the performance of the standard CMA by using a dynamically partitioned hierarchical structure to organize the taps of a filter. The filter length is dynamically partitioned according to the delay spread such that they are tightly matched. Preferably, the length of a sub-filter is slightly longer than the delay spread of the channel. The performance evaluation is divided into two parts. In Part I, we do simulation runs for both the cost functions and cost surfaces comparing the standard CMA, where the filter length is significantly longer than the delay spread, and the dynamically partitioned CMA, where the filter length matches the delay spread. In Part II, an analysis is provided to show that the proposed partitioned scheme can speed up the convergence rate and reduce the cost function.

关键词： Adaptive filtering CMA constant modulus algorithm Hierarchical filtering

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Fuzzy-logic tuned constant modulus algorithm and soft decision-directed scheme for blind equalisation

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DIGITAL SIGNAL PROCESSING 2010年第3期20卷 846-859页

作者： Chen, S. Luk, B. L. Harris, C. J. Hanzo, L. Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England City Univ Hong Kong Dept Mfg Engn & Engn Management Hong Kong Hong Kong Peoples R China

This contribution revisits blind equalisation for high-order quadrature amplitude modulation systems using a low-complexity high-performance concurrent constant modulus algorithm (CMA) and soft decision-directed (SDD) scheme. A fuzzy-logic (FL) tuning unit is designed to adjust the step size of the CMA, and the potential benefits of using this adaptive step size approach are investigated. Simulation results obtained confirm that faster convergence can be achieved with this FL assisted CMA and SDD scheme, compared with the previous constant step-size CMA and SDD scheme. Quantitatively, the former requires several thousands fewer samples to converge to the same steady-state solution achieved by the latter. (C) 2009 Elsevier Inc. All rights reserved.

关键词： Blind equalisation Quadrature amplitude modulation constant modulus algorithm Soft decision-directed adaptation Minimum mean square error Adaptive step size Fuzzy logic

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Hardware-assisted initialisation for constant modulus algorithm adaptive antenna

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IET MICROWAVES ANTENNAS & PROPAGATION 2008年第4期2卷 303-311页

作者： Boonpoonga, A. Sirisuk, P. Chongcheawchamnan, M. Patisang, S. Krairiksh, M. King Mongkuts Inst Technol Ladkrabang Fac Engn Bangkok 10520 Thailand King Mongkuts Inst Technol Ladkrabang Res Ctr Commun & Informat Technol Bangkok 10520 Thailand Mahanakorn Univ Technol Fac Engn Bangkok 10530 Thailand

A cost-effective approach for initialisation of an adaptive antenna based on the constant modulus algorithm (CMA) is proposed. The technique utilises 1 bit phase shifters and a power detector, which are normally integrated with a multibeam antenna, to determine the maximum power beam direction. Consequently, the beam is exploited as an initial beam for CMA. Development of hardware-assisted initialisation is discussed. In addition field programmable gate array implementation of a CMA processor and associated control circuitry is presented. Several simulations are performed to evaluate the performance of the proposed initialisation technique. In addition, the developed prototype is tested with a phase array antenna designed for operation at the IMT2000 frequency of 1.95 GHz. Experimental results confirm superiority of the proposed technique.

关键词： Other analogue circuits field programmable gate arrays multibeam antenna field programmable gate array constant modulus algorithm hardware-assisted initialisation adaptive antenna arrays phase shifters associated control circuitry Logic circuits CMA processor CMA based adaptive antenna Antenna arrays power detector

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Adaptive step-size constant modulus algorithm for DS-CDMA receivers in nonstationary environments

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SIGNAL PROCESSING 2002年第2期82卷 311-315页

作者： Yuvapoositanon, P Chambers, JA Univ Bath Dept Elect & Elect Engn Signal & Image Proc Grp Bath BA2 7AY Avon England Mahanakorn Univ Technol Dept Elect Engn Bangkok 10530 Thailand

A new adaptive step-size constant modulus algorithm for direct-sequence code division multiple access receivers is presented for application in nonstationary channel conditions. The algorithm is derived upon the basis of adapting the step-size to minimise the constant modulus criterion and its convergence is verified analytically. Simulations show the superior performance of the proposed method over similar adaptive receivers and its robustness to different settings of the initial step-size. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： constant modulus algorithm adaptive step-size DS-CDMA receivers

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Multi-Beam Massive MIMO Using constant modulus algorithm for QAM Signals Employing Amplitude and Phase Offset Compensation

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IEICE TRANSACTIONS ON COMMUNICATIONS 2017年第2期E100B卷 262-268页

作者： Taniguchi, Ryotaro Nishimori, Kentaro Makino, Hideo Niigata Univ Grad Sch Sci & Technol Niigata 9502102 Japan

Massive MIMO transmission, whose number of antennas is much larger than the number of user terminals, has been attracted much attention as one of key technologies in next-generation mobile communication system because it enables improvement in service area and interference mitigation by simple signal processing. Multi-beam massive MIMO has proposed that utilizes the beam selection with high power in analog part and blind algorithm such as constant modulus algorithm (CMA) which does not need channel state information (CSI) is applied in digital part. Proposed configuration obtains high transmission efficiency. We have evaluated QPSK signals because the CMA basically focuses on the constant amplitude modulation. In this paper, in order to achieve the further higher transmission rate, the amplitude and phase compensation scheme is proposed when using the CMA with amplitude and phase modulation scheme such as QAM. The effectiveness of proposed method is verified by the computer simulation.

关键词： massive MIMO multi-beam constant modulus algorithm quadrature amplitude and phase modulation

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A Supervised constant modulus algorithm for Blind Equalization

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WIRELESS PERSONAL COMMUNICATIONS 2012年第1期62卷 151-166页

作者： Ozen, A. Kaya, I. Soysal, B. Karadeniz Tech Univ DSP LAB Dept Elect & Elect Engn Trabzon Turkey Ataturk Univ Fac Engn Dept Elect & Elect Engn Erzurum Turkey

Blind equalization is a technique for adaptive equalization of a communication channel without the aid of the usual training sequence. Although the constant modulus algorithm (CMA) is one of the most popular adaptive blind equalization algorithms, it suffers from slow convergence rate. A novel enhanced blind equalization technique based on a supervised CMA (S-CMA) is proposed in this paper. The technique is employed to initialize the coefficients of a linear transversal equalizer (LTE) filter in order to provide a fast startup for blind training. It also presents a computational study and simulation results of this newly proposed algorithm compared to other CMA techniques such as conventional CMA, Normalized CMA (N-CMA) and Modified CMA (M-CMA). The simulation results have demonstrated that the proposed algorithm has considerably better performance than others.

关键词： Blind channel equalization constant modulus algorithm Supervised-CMA Adaptive blind training

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A batch processing constant modulus algorithm

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IEEE COMMUNICATIONS LETTERS 2004年第9期8卷 582-584页

作者： Xu, CJ Li, J Univ Florida Dept Elect & Comp Engn Gainesville FL 32611 USA Nanjing Univ Posts & Telecommun Dept Telecommun Engn Nanjing 210003 Peoples R China

We present a batch processing constant modulus algorithm (BP-CMA) derived by a nonlinear optimization approach to minimizing the constant modulus (CM) criterion. BP-CMA is a line search iteration algorithm. The search direction may be taken as deepest descent direction or Newton direction. The exact step size is obtained from the roots of a cubic equation. The initial value is calculated by using the eigenvectors of the signal subspace. The BP-CMA with the Newton direction has a fast convergence rate and can converge to the minima of the CM criterion after a few iterations.

关键词： batch processing algorithm constant modulus algorithm signal-subspace

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Polarization demultiplexing by recursive least squares constant modulus algorithm based on QR decomposition

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OPTICS AND LASER TECHNOLOGY 2013年 49卷 251-255页

作者： Zhao Ling Wang Yeling Hu Guijun Cui Yunpeng Shi Jian Li Li Jilin Univ Dept Opt Commun Coll Commun Engn Changchun 130012 Peoples R China Jilin Univ Hosp 1 Changchun 130021 Peoples R China

Recursive least squares constant modulus algorithm based on QR decomposition (QR-RLS-CMA) is first proposed as the polarization demultiplexing method. We compare its performance with the stochastic gradient descent constant modulus algorithm (SGD-CMA) and the recursive least squares constant modulus algorithm (RLS-CMA) in a polarization-division-multiplexing system with coherent detection. It is demonstrated that QR-RLS-CMA is an efficient demultiplexing algorithm which can avoid the problem of step-length choice in SGD-CMA. Meanwhile, it also has better symbol error rate (SER) performance and more stable convergence property. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Optical fiber communication Polarization-division-multiplexing constant modulus algorithm

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