constant modulus algorithm (CMA) is widely applied for polarization demultiplexing in coherent optical communication system. However, the singular value problem always plagues CMA. Modified CMA based on polarization d...
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constant modulus algorithm (CMA) is widely applied for polarization demultiplexing in coherent optical communication system. However, the singular value problem always plagues CMA. Modified CMA based on polarization demultiplexing in Stokes space (SS-PDM) was proposed to avoid the singular value problem in simulation. Here we firstly experimentally demonstrate the modified CMA based on SS-PDM in optical coherent receivers. We conduct experiment of 40-Gbit/s polarization multiplexing (PDM) QPSK to verify this method. The experimental results show that the singularity problem of CMA disappears for Polarization-dependent loss (PDL) of 2.7 dB and 4.8 dB by using the modified CMA and the convergence speed of the modified CMA increases significantly compared with that of conventional CMA.
In this paper we present an approach to equalize multipath transmitted video signals without any reference signal. This approach takes advantage of the constant envelope feature of the color burst signal, which is tra...
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In this paper we present an approach to equalize multipath transmitted video signals without any reference signal. This approach takes advantage of the constant envelope feature of the color burst signal, which is transmitted in the blanking interval of each TV line and can be considered as an angle-modulated signal. The constant modulus algorithm (CMA) after Treichler is modified for our purpose. Special attention is given to the equalization of video signals in PAL systems. By making full use of the genuine phase feature of the color burst signal in PAL systems, the Hilbert transform needed by CMA can be saved for equalizing PAL system video signals. In addition to equalize analog TV signal, this paper can also lead to a joint echo cancellation of analog and digital TV signals transmitted in cable network. (C) 2001 Elsevier Science B.V. All rights reserved.
This paper investigates a blind space-time equaliser (STE) designed for single-input multiple-output (SIMO) systems that employ high-throughput quadrature amplitude modulation schemes. A constant modulus algorithm (CM...
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This paper investigates a blind space-time equaliser (STE) designed for single-input multiple-output (SIMO) systems that employ high-throughput quadrature amplitude modulation schemes. A constant modulus algorithm (CMA) aided soft decision-directed (SDD) scheme, originally derived for low-complexity blind equalisation of single-input single-output channels, is extended to the SIMO scenario. Simulations are conducted to compare the performance of this blind adaptive scheme with another low-complexity blind STE referred to as the CMA aided decision directed (DD) scheme. The results obtained demonstrate that for SIMO systems the CMA aided SDD scheme exhibits advantages over the CMA aided DD arragement, in terms of its faster convergence speed and lower computational complexity.(c) 2007 Elsevier B.V. All rights reserved.
Based on a uniform linear array, a new widely linear unscented Kalman filter-based constant modulus algorithm (WL-UKF-CMA) for blind adaptive beamforming is proposed. The new algorithm is designed according to the con...
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Based on a uniform linear array, a new widely linear unscented Kalman filter-based constant modulus algorithm (WL-UKF-CMA) for blind adaptive beamforming is proposed. The new algorithm is designed according to the constantmodulus criterion and takes full advantage of the noncircular property of the signal of interest (SOI), significantly increasing the output signal-to interference-plus-noise ratio (SINR), enhancing the convergence speed and decreasing the steady-state misadjustment. Since it requires no known training data, the proposed algorithm saves a large amount of the available spectrum. Theoretical analysis and simulation results are presented to demonstrate its superiority over the conventional linear least mean square-based CMA (L-LMS-CMA), the conventional linear recursive least square-based CMA (L-RLS-CMA), WL-LMS-CMA, WL-RLS-CMA and L-UKF-CMA.
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...
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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 (c) 2004 John Wiley & Sons, Ltd.
This paper quantifies the adaptive performance of a blind adaptive multiuser detector (MUD) based on the linearly constrained constant modulus algorithm (LCCMA) in both a stationary and nonstationary channel. A framew...
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This paper quantifies the adaptive performance of a blind adaptive multiuser detector (MUD) based on the linearly constrained constant modulus algorithm (LCCMA) in both a stationary and nonstationary channel. A framework is developed to apply the feedback analysis method to analyzing adaptive MUD schemes. A closed-form expression for the excess mean square error (EMSE) of LCCMA blind adaptive MUD in a CDMA communications system is derived for both of the steady-state and tracking cases. The effects of additive noise and multiple access interference are considered. A transient analysis is performed that predicts the learning curve of the adaptive filter. Computer simulation is used to verify the accuracy of the analysis.
We propose a modified method of constant modulus algorithm (CMA) based on polarization demultiplexing in Stokes space for polarization demultiplexing (SS-PDM) in optical coherent receivers. SS-PDM can tolerate chromat...
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We propose a modified method of constant modulus algorithm (CMA) based on polarization demultiplexing in Stokes space for polarization demultiplexing (SS-PDM) in optical coherent receivers. SS-PDM can tolerate chromatic dispersion (CD) and polarization-dependent loss (PDL), but is sensitive to PMD. On the other hand, the CMA with high-order FIR filters could compensate for polarization-mode-dispersion (PMD) effectively, but suffers from the singularity problem which results from PDL. Therefore, we use the polarization rotation matrix estimated by SS-PDM to set the initial center taps of the CMA. The singularity problem of the CMA is avoided effectively in a much wider range of PDL and its convergence speed is also improved. We demonstrate this modified CMA in a simulation of 100-Gbit/s PDM-QPSK with PDL of 1, 3, and 5 dB, respectively. PDL is emulated by attenuating one polarization tributary before polarization multiplexing and the interaction between PDL and PMD is ignored. The singularity problem disappears as expected. Because the tolerance of PDL is affected by DGD, we further investigate the PDL tolerance under different DGD. Finally, we conduct the simulation of 100-Gbit/s PDM-QPSK with PDL of 3 dB over 3000 km SSMF and 4000 km SSMF separately. The convergence speed accelerates indeed compared with that of the conventional CMA.
Blind equalization is a technique of adapting an equalizer without the need of a training sequence, The constant modulus algorithm (CMA) is one of the first known blind equalization algorithms. The cost function of th...
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Blind equalization is a technique of adapting an equalizer without the need of a training sequence, The constant modulus algorithm (CMA) is one of the first known blind equalization algorithms. The cost function of the CMA exhibits local minima, which are the primary cause of the ill-convergence of the CMA, Using the CMA with an anchored equalizer greatly improves the performance of the CMA in terms of ill-convergence. This technique is used in this paper with the linear and the decision feedback equalizers, Theory and simulation show that such an adaptive equalizer will always remove intersymbol interference (ISI) provided the main cursor's gain exceeds a certain critical value.
This paper presents an efficient meta-heuristic algorithm based on electromagnetism-like method, which has been successfully implemented in multiuser detection problems. The contribution revisits blind multiuser detec...
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This paper presents an efficient meta-heuristic algorithm based on electromagnetism-like method, which has been successfully implemented in multiuser detection problems. The contribution revisits blind multiuser detection for multicarrier code division multiple access systems using a novel combined adaptive step-size constant modulus algorithm (CMA) and electromagnetism-like method scheme. To work around potentially computational intractability and improved the capability of suppressing multiple access interference (MAI) for Multicarrier CDMA System, the proposed scheme exploits heuristics in consideration of both global and local exploration of the step size of the CMA. Simulation results obtained confirm that faster convergence and desirable BER performance with low computational complexity can be achieved with electromagnetism-like method based CMA scheme, compared with the previous step-size CMA scheme, genetic algorithm, and particle swarm optimization with CMA scheme. Copyright (c) 2012 John Wiley & Sons, Ltd.
作者：
Kanmani, M.Kannan, M.Anna Univ
Dept ECE Jerusalem Coll Engn Madras 600025 Tamil Nadu India Anna Univ
Dept Elect Engn Madras Inst Technol Madras 600025 Tamil Nadu India
Multiple-Input Multiple-Output system plays a major role in the fourth generation wireless systems to provide high data rates. In this paper, a blind channel estimation approach has been proposed for finding the chann...
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Multiple-Input Multiple-Output system plays a major role in the fourth generation wireless systems to provide high data rates. In this paper, a blind channel estimation approach has been proposed for finding the channel length based on the signals received from the MIMO (Multiple-Input Multiple-Output) transceiver. The resultant MIMO channel length information is utilized for estimation of the channel impulse response of the system. The estimation is used for adaptation of the equalizer weights, based on the proposed constant modulus algorithm which has reduced the fading and multipath propagation resulting from Inter Symbol Interference. The performance of the proposed system has been analyzed in terms of Mean Square Error and Symbol Error Rate for various Signal to Noise Ratio. (C) 2015 Elsevier Ltd. All rights reserved.
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