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Constant Modulus Algorithm (constant + modulus_algorithm)
Selected AbstractsSemi-blind fast equalization of QAM channels using concurrent gradient-Newton CMA and soft decision-directed schemeINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2010S. Chen Abstract This contribution considers semi-blind adaptive equalization for communication systems that employ high-throughput quadrature amplitude modulation signalling. A minimum number of training symbols, approximately equal to the dimension of the equalizer, are first utilized to provide a rough initial least-squares estimate of the equalizer's weight vector. A novel gradient-Newton concurrent constant modulus algorithm and soft decision-directed scheme are then applied to adapt the equalizer. The proposed semi-blind adaptive algorithm is capable of converging fast and accurately to the optimal minimum mean-square error equalization solution. Simulation results obtained demonstrate that the convergence speed of this semi-blind adaptive algorithm is close to that of the training-based recursive least-square algorithm. Copyright © 2009 John Wiley & Sons, Ltd. [source] The performance analyses of multitarget CMA adaptive array considering mutual coupling and diffraction effectsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2007Jin Xu Abstract The performance of a multitarget constant modulus algorithm (MU-CMA) adaptive array located on a regular conducting plate is studied in this paper. The effects of mutual coupling (MC) between array elements and diffraction caused by the conducting plate are taken into account. A hybrid method of equivalent edge current method (ECM) and moment method (MM) is employed in electromagnetic calculation to investigate the distortion of initial array pattern. We compare the capture property of three well-known MU-CMA arrays, respectively: multitarget least-squares constant modulus array (MT-LSCMA), multitarget decision-directed array (MT-DD) and least-squares despread respread multitarget constant modulus array (LS-DRMTCMA). Simulation result shows that: (i) the distorted initial pattern leads to the descending of the signal catch performance of MT-LSCMA and MT-DD; (ii) only the LS-DRMTCMA can work correctly due to its stronger anti-jamming ability in the presence of MC and diffraction. Copyright © 2006 John Wiley & Sons, Ltd. [source] Convergence analysis of blind image deconvolution via dispersion minimizationINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2006C. Vural Abstract A new non-linear adaptive filter called blind image deconvolution via dispersion minimization has recently been proposed for restoring noisy blurred images blindly. This is essentially a two-dimensional version of the constant modulus algorithm that is well known in the field of blind equalization. The two-dimensional extension has been shown capable of reconstructing noisy blurred images using partial a priori information about the true image and the point spread function in a variety of situations by means of simulations. This paper analyses the behaviour of the algorithm by investigating the static properties of the cost function and the dynamic convergence of the parameter estimates. The theoretical results are supported with computer simulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Fractionally spaced blind equalization with low-complexity concurrent constant modulus algorithm and soft decision-directed schemeINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2005S. Chen Abstract The paper proposes a low-complexity concurrent constant modulus algorithm (CMA) and soft decision-directed (SDD) scheme for fractionally spaced blind equalization of high-order quadrature amplitude modulation channels. We compare our proposed blind equalizer with the recently introduced state-of-art concurrent CMA and decision-directed (DD) scheme. The proposed CMA+SDD blind equalizer is shown to have simpler computational complexity per weight update, faster convergence speed, and slightly improved steady-state equalization performance, compared with the existing CMA+DD blind equalizer. Copyright © 2004 John Wiley & Sons, Ltd. [source] Interference rejection in non-Gaussian noise for satellite communications using non-linear beamformingINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2003Chang Qing Xu Abstract In this paper, non-linear beamforming based on the method of radial basis functions (RBF) is proposed to combine with constant modulus algorithm (CMA) for interference cancellation in non-Gaussian noise. First, a signal space is constructed from the input array data vectors utilizing RBF. A set of exponential functions is used to transform the Euclidean norm of the input array data vectors into the signal space. Then, CMA is employed to eliminate the interference. Both Gaussian and non-Gaussian noise are considered in the experiment. The numerical results indicate that this scheme is effective and robust in terms of interference cancellation. A deep null can be formed to the direction of interference for both Gaussian and non-Gaussian noise. Furthermore, these results are compared with that of DBF with CMA based on FFT technique, a widely used linear beamforming technique. The comparison shows that a DBF array antenna with CMA based on the method of RBF outperforms its counterpart based on FFT technique. The most interesting result is that the proposed method has a robust interference cancellation performance in non-Gaussian noise whereas the FFT technique fails to do so. This observation can be very useful in satellite communications because that non-Gaussian noise such as atmospheric and man-made noise are often encountered in satellite communications. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||