A robust algorithm for blind space-time equalization (original) (raw)
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An accelerated constant modulus algorithm for space-time blind equalization
We address the problem of signal separation using space-time blind equalization techniques. A novel blind algorithm, denoted ACMA (Accelerated Constant Modulus Algorithm), is proposed. It minimizes the constant modulus cost function and is based on a tuner used in adaptive control that sets the second derivative ("acceleration") of the coefficient estimates. Both the convergence speed and computational complexity of Multiuser ACMA lie between those of the Multiuser Constant Modulus and the Multiuser Shalvi-Weinstein algorithms. Some preliminary results show that the proposed algorithm presents a robust behavior with respect to global minima and tracking capability.
Deterministic Blind Subspace MIMO Equalization
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A subspace based approach for the blind multiple signal separation and recovery for MIMO systems is proposed in this paper. Instead of using the statistics of the received signal, the proposed algorithm exploits the received signal structure and the finite alphabet property of the desired signals. The finite alphabet property is used to remove the unknown unitary matrix that is associated with most of the statistics-based MIMO system identification algorithms. The proposed algorithm also incorporates an error-correcting procedure; therefore, it has more accuracy than the existing algorithms. Computer simulation results demonstrate that the algorithm can detect the signals and estimate channel parameters accurately with very few symbols, even under high noise and bad channel conditions.
BLIND MIMO PARA-UNITARY EQUALIZATION
2004
LABORATOIRE I3S: Les Algorithmes / Euclide B -2000 route des Lucioles -B.P. 121 -06903 Sophia-Antipolis Cedex, France -Tél. (33) 492 942 701 -Télécopie : (33) 492 942 898 http://www.i3s.unice.fr/I3S/FR/
Blind MIMO paraunitary equalizer
2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)., 2003
This paper introduces a new Blind Source Separation algorithm for convolutive mixtures. In addition to separate sources, this algorithm respects the paraunitary property of the model considered, obtained after whitening observations. In order to do this, the equalizer is factorized in a novel manner. After a presentation of theoretical results, a numerical algorithm is then derived. This algorithm is based on the solution of a polynomial system, which some values of output cumulant multi-correlations enter. Simulations and performances of the numerical algorithm are presented in the last section.
Semi-Blind Gradient-Newton CMA and SDD Algorithm for MIMO Space-Time Equalisation
GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference, 2009
Semi-blind space-time equalisation is considered for dispersive multiple-input multiple-output systems that employ high-throughput quadrature amplitude modulation signalling. A minimum number of training symbols, approximately equal to the dimension of the space-time equaliser (STE), are first utilised to provide a rough initial least squares estimate of the STE's weight vector. A gradient-Newton-type concurrent constant modulus algorithm and soft decision-directed scheme is then applied to adapt the STE. The proposed semi-blind adaptive STE is capable of converging fast and accurately to the optimal minimum mean square error STE solution.
Blind multiuser equalization using a PARAFAC-subspace spproach
2005
Dans cet article, nous utilisons la décomposition tensorielle PARAFAC (PARAllel FACtors) en vue de développer une nouvelle approche pour l'égalisation aveugle multi-utilisateur dans le cadre des systèmes de communications sans fil. Le système considéré est basé sur l'utilisation conjointe d'un réseau d'antennes et d'un sur-échantillonnage à la réception. Nous proposons tout d'abord un modèle tridimensionnel du type PARAFAC pour le signal reçu, dont les 3 dimensions sont l'espace, le temps et le sur-échantillonnage. Ensuite, nous présentons un nouveau récepteur aveugle multi-utilisateur pour la séparation des signaux et pour l'égalisation. Le récepteur proposé combine une modélisation PARAFAC, une méthode de sous-espace et l'exploitation de la propriété d'alphabet fini des symboles transmis. Des résultats de simulations sont montrés pour illustrer la performance du récepteur aveugle proposé.
Blind multichannel equalization using a novel subspace method
IEEE Transactions on Signal Processing, 2000
This correspondence develops a new blind multichannel equalization (BME) scheme and proposes an appropriate cost function by the exploitation of some shifting properties of the autocorrelation matrices of the source. In addition, an efficient programming is considered based on a generalized rayleigh quotient formulation using a conjugate gradient algorithm.
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 2006
The present letter deals with the blind equalization problem of a single-input single-output infinite impulse response (SISO-IIR) channel with additive Gaussian noise. To solve the problem, we propose a new criterion for maximizing constrainedly a fourth-order cumulant. The algorithms derived from the criterion have such a novel property that even if Gaussian noise is added to the output of the channel, an effective zeroforcing (ZF) equalizer can be obtained with as little influence of Gaussian noise as possible. To show the validity of the proposed criterion, some simulation results are presented.
Multiuser processing using blind source separation methods
European Transactions on Telecommunications, 2008
Multiuser Processing refers to a set of fundamental techniques for improving the performance of the modern wireless communications systems. Most of these techniques have been proposed and studied for specific scenarios, according to the multiple access technology to be employed. The theory and methods of blind source separation (BSS) can provide a more general framework over which multiuser techniques may be investigated and analyzed as a particular case. This is the main idea to be exploited along the present paper. We show how this point of view opens perspectives to deal with important problems of multiuser systems, such as signal detection and collision resolution. For this task, an information-theoretic based criterion and algorithm, issued from BSS theory, is presented together with an algorithm for estimation of the number of active users in the system. Simulation results are carried out to illustrate the performance of the designed approach, compared to other blind and trained solutions.
Blind paraunitary equalization
Signal Processing, 2009
In this paper a blind MIMO space-time equalizer is described, dedicated to convolutive mixtures when observations have been pre-whitened. Filters preserving space-time whiteness are paraunitary; a parameterization of such filters is proposed. Theoretical developments then lead to a numerical algorithm that sweeps all pairs of delayed outputs. This algorithm involves the solution of a polynomial system, whose coefficients depend on the output cumulants. Simulations and performance of the numerical algorithm are reported.