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Blind source separation of convolutive mixtures of non-circular linearly modulated signals with unknown baud rates

SIGNAL PROCESSING 2012年第3期92卷 715-726页

作者： Florian, E. Chevreuil, A. Loubaton, Ph. Sequans Commun F-92073 Le Parvis De La Def Paris La Defens France Univ Paris Est LIGM CNRS UMR 8049 F-77454 Marne La Vallee 2 France ESIEE Paris F-93162 Noisy Le Grand France

This paper addresses the problem of blind separation of convolutive mixtures of BPSK and circular linearly modulated signals with unknown (and possibly different) baud rates and carrier frequencies. In previous works, we established that the constant modulus algorithm (CMA) is able to extract a source from a convolutive mixture of circular linearly modulated signals. We extend the analysis of the extraction capabilities of the CMA when the mixing also contains BPSK signals. We prove that if the various source signals do not share any non-zero cyclic frequency nor any non-conjugate cyclic frequencies, the local minima of the constant modulus cost function are separating filters. Unfortunately, the minimization of the Godard cost function generally fai s when considering BPSK signals that have the same rates and the same carrier frequencies. This failure is due to the existence of non-separating local minima of the Godard cost function. In order to achieve the separation, we propose a simple modification of the Godard cost function which only requires knowledge of the BPSK sources frequency offsets at the receiver side. We provide various simulations of realistic digital communications scenarios that support our theoretical statements. (C) 2011 Elsevier B.V. AB rights reserved.

关键词： Blind source separation Convolutive mixture constant modulus algorithm Cyclostationarity

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Convergence analysis of blind image deconvolution via dispersion minimization

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INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING 2006年第7期20卷 321-336页

作者： Vural, C. Sethares, W. A. Sakarya Univ TR-54187 Sakarya Turkey Univ Wisconsin Dept Elect & Comp Engn Madison WI 53706 USA

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 (c) 2006 John Wiley & Sons, Ltd.

关键词： blind image deconvolution non-linear adaptive filtering constant modulus algorithm convergence analysis

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Blind separation of BPSK sources with residual carriers

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SIGNAL PROCESSING 1999年第1-2期73卷 67-79页

作者： van der Veen, AJ Delft Univ Technol Dept Elect Engn NL-2628 CD Delft Netherlands

Blind separation of instantaneous mixtures of binary sources with equal carrier frequencies has been studied before. For independent sources, it may be reasonable to assume that their carrier frequencies are not exactly identical, so that a residual carrier is present after demodulation to baseband. We show how this can be used to separate the sources. If the receiving antenna array is centro-symmetric and there is no multipath, then the performance of the algorithm can be significantly improved. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： blind source separation constant modulus algorithm residual carrier blind beamforming

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Novel Non-Data-Aided Clock Recovery Method for DP-QPSK Systems With CMA Equalizers

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IEEE PHOTONICS TECHNOLOGY LETTERS 2012年第19期24卷 1696-1699页

作者： Portela, Thiago F. Mello, Darli A. A. Univ Brasilia Dept Elect Engn OCNLab BR-70919970 Brasilia DF Brazil

We propose a novel non-data-aided clock recovery method for differential quadrature phase-shift keying optical systems based on the coefficients of the constant modulus algorithm (CMA) adaptive equalizer. The new technique exhibits a satisfactory performance under certain combinations of differential group delay (DGD) and state of polarization, in which the traditional Gardner algorithm fails. The robustness of the proposed algorithm against chromatic dispersion, DGD, and state of polarization variations is demonstrated experimentally.

关键词： Chromatic dispersion clock and data recovery constant modulus algorithm differential group delay digital signal processing optical communication system

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A new blind-equalization algorithm for an FIR SIMO system driven by MPSK signal

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2007年第3期54卷 227-231页

作者： Gu, Nong Xiang, Yong Tan, Min Cao, Zhiqiang Deakin Univ Sch Engn & Informat Technol Geelong Vic 3217 Australia Chinese Acad Sci Inst Automat Beijing 100080 Peoples R China

We consider the problem of blind equalization of a finite impulse response and single-input multiple-output system driven by an M-ary phase-shift-keying signal. The existing singlemode'algorithms for this problem include the constant modulus algorithm (CMA) and the multimodulus algorithm (MMA). It has been shown that the MMA outperforms the CMA when the input signal has no more than four constellation points, i.e., M <= 4. In this brief, we present a new adaptive equalization algorithm that jointly exploits the amplitude and phase information of the input signal. Theoretical analysis shows that the proposed algorithm has less mean square error, i.e., better equalization performance, at steady state than the CMA regardless of the value of M. The superior performance of our algorithm to the CMA and the NIMA is validated by simulation examples.

关键词： blind system equalization constant modulus algorithm finite-impulse response (FIR) single-input multiple-output (SIMO) system M-ary phase-shift-keying (MPSK) signal

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Enhanced Blind Equalization for Optical DP-QAM in Finite Precision Hardware

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IEEE PHOTONICS TECHNOLOGY LETTERS 2015年第2期27卷 181-184页

作者： Ragheb, Amr M. Shoaib, Mobien Alshebeili, Saleh Fathallah, Habib King Saud Univ Dept Elect Engn Riyadh 11421 Saudi Arabia King Saud Univ King Abdulaziz City Sci & Technol Technol Innovat Riyadh 11451 Saudi Arabia King Saud Univ Prince Sultan Adv Technol Res Inst Riyadh 11421 Saudi Arabia

In this letter, we apply the inverse QR decomposition-constant modulus algorithm (IQRD-CMA), blind equalization technique, for impaired 14 GBd DP-16 quadratic-amplitude modulation optical modulated signal. The IQRD-CMA is considered here to mitigate the effect of residual chromatic dispersion (CD) and polarization mode dispersion (PMD). We evaluate the performance of the proposed inverse QR decomposition in terms of convergence rate, steady-state/residual mean square error (MSE), and bit error rate (BER), in comparison with standard blind constant modulus algorithm (CMA) and recursive least squares (RLS-CMA). Assuming infinite precision, the IQRD-CMA and RLS-CMA achieve similar performance and induce the same computational complexity;however, both largely outperform standard CMA for wide ranges of CD and PMD. However, for finite precision hardware, compared with RLS-CMA, the proposed blind IQRD-CMA clearly achieves one order of BER magnitude at 8-and 10-b resolutions, and further reduces the steady-state MSE by 3 dB. Moreover, results show that IQRD-CMA maintains the system stability at acceptable number of bits resolutions. In addition, this letter addresses the tradeoff between the complexity and the performance of all these equalizers for several precision settings.

关键词： Inverse QR decomposition (IQRD) recursive least squares (RLS) coherent optical communications constant modulus algorithm

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Blind cascaded fractionally-spaced and baud-spaced equaliser

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ELECTRONICS LETTERS 1998年第17期34卷 1635-1637页

作者： Sirisuk, P constantinides, AG Univ London Imperial Coll Sci Technol & Med Dept Elect Engn Signal Proc & Digital Syst Sect London SW7 2BT England

The authors address the problem of fractionally-spaced blind equalisation when there exist common zero(s) among subchannels. They propose a new cascaded fractionally-spaced and baud-spaced structure to tackle this difficulty. The recent constant modulus algorithm under soft constraint satisfaction (SCS-CMA) is used to demonstrate the feasibility of the technique. Simulations show that the performance of the proposed scheme is superior to those of both fractionally-spaced and baud-spaced CMAs, when channels have common zero(s).

关键词： equalisers blind cascaded fractionally-spaced equaliser constant modulus algorithm telecommunication channels soft constraint satisfaction Information theory common zero baud-spaced equaliser

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Novel Blind Equalizer for Coherent DP-BPSK Transmission Systems: Theory and Experiment

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IEEE PHOTONICS TECHNOLOGY LETTERS 2013年第18期25卷 1835-1838页

作者： Pincemin, Erwan Brochier, Nicolas Selmi, Mehrez Chahabi, Omid Zia Ciblat, Philippe Jaouen, Yves Orange Labs France Telecom Dept Orange Labs Network F-22300 Lannion France Telecom Paristech COMELEC F-75039 Paris France

Adaptive blind equalization based on constant modulus algorithm is very efficient to carry out polarization separation and inter-symbol interference compensation in a coherent dual-polarization quaternary-phase-shift-keying transmission system. Its performance is, however, very poor when coherent dual-polarization binary-phase-shift-keying (BPSK) modulation is considered. In this letter, we propose a new blind equalizer adapted to any PSK constellation and we theoretically show its convergence. Experimental BER measurements and convergence analysis are performed in a 40 Gbps coherent dual-polarization BPSK system under different physical impairments. We show that our equalizer outperforms existing blind algorithms.

关键词： Coherent optical communications binary-phase shift-keying blind equalization constant modulus algorithm

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Blind Source Separation and Equalization Based on Support Vector Regression for MIMO Systems

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IEICE TRANSACTIONS ON COMMUNICATIONS 2018年第3期E101B卷 698-708页

作者： Sun, Chao Yang, Ling Du, Juan Sun, Fenggang Chen, Li Xi, Haipeng Du, Shenglei Lanzhou Univ Sch Informat Sci & Engn Lanzhou 730000 Gansu Peoples R China Shandong Agr Univ Sch Informat Sci & Engn Tai An 271000 Shandong Peoples R China

In this paper, we first propose two batch blind source separation and equalization algorithms based on support vector regression (SVR) for linear time-invariant multiple input multiple output (MIMO) systems. The proposed algorithms combine the conventional cost function of SVR with error functions of classical on-line algorithm for blind equalization: both error functions of constant modulus algorithm (CMA) and radius directed algorithm (RDA) are contained in the penalty term of SVR. To recover all sources simultaneously, the cross-correlations of equalizer outputs are included in the cost functions. Simulation experiments show that the proposed algorithms can recover all sources successfully and compensate channel distortion simultaneously. With the use of iterative re-weighted least square (IRWLS) solution of SVR, the proposed algorithms exhibit low computational complexity. Compared with traditional algorithms, the new algorithms only require fewer samples to achieve convergence and perform a lower residual interference. For multilevel signals, the single algorithms based on constant modulus property usually show a relatively high residual error, then we propose two dual-mode blind source separation and equalization schemes. Between them, the dual-mode scheme based on SVR merely requires fewer samples to achieve convergence and further reduces the residual interference.

关键词： MIMO systems blind source separation blind equalization support vector regression constant modulus algorithm radius directed algorithm

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Development of blind algorithm with automatic gain control

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WIRELESS NETWORKS 2020年第4期26卷 2413-2422页

作者： Yasin, Muhammad Khan, Muhammad Junaid Natl Univ Sci & Technol Islamabad Pakistan

In this paper, the concept of blind algorithm with automatic gain control (AGC) is introduced in adaptive antenna system for signal optimization with an aim to estimate the desired response in adaptive fashion. Blind algorithm with AGC is a hybrid two-stage adaptive filtering algorithm;sequentially combining constant modulus algorithm (CMA) and Bessel least mean square (BLMS) algorithm. Blind Bessel beamformer with AGC does not require external reference signal to update its weight vectors and step size for convergence but updates itself from own reference signal obtained from the output of CMA. Similarly, step size is obtained from the correlation matrix which is the product of the signals induced in array elements of antenna. BLMS is the modified version of LMS algorithm;based on the non-uniform step size exploiting the asymptotic decay property of Bessel function of the first kind. The output of CMA provides input and reference signals for BLMS that makes it blind. The contributions of this paper include the development of novel blind theory concept and presentation of an AGC method in order to make the Bessel beamformer blind which can update itself electronically through the correlation matrix depending on the signal array vector with the aim to make the signal power constant.

关键词： Blind Bessel beamformer constant modulus algorithm Smart antenna Beamforming

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