This paper analyzes the convergence of the constant modulus algorithm (CMA) in a decision feedback equalizer using only a feedback filter. Several works had already observed that the CMA presented a better performance...
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This paper analyzes the convergence of the constant modulus algorithm (CMA) in a decision feedback equalizer using only a feedback filter. Several works had already observed that the CMA presented a better performance than decision directed algorithm in the adaptation of the decision feedback equalizer, but theoretical analysis always showed to be difficult specially due to the analytical difficulties presented by the constant modulus criterion. In this paper, we surmount such obstacle by using a recent result concerning the CM analysis, first obtained in a linear finite impulse response context with the objective of comparing its solutions to the ones obtained through the Wiener criterion. The theoretical analysis presented here confirms the robustness of the CMA when applied to the adaptation of the decision feedback equalizer and also defines a class of channels for which the algorithm will suffer from ill-convergence when initialized at the origin.
A new concurrent scheme for blind equalization suitable for 16-QAM signal is proposed. It combines Modified Modulus algorithm (MCMA) and Modified decisiondirected (MDD) algorithm. By exploiting the inherent structura...
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ISBN:
(纸本)9781424448562
A new concurrent scheme for blind equalization suitable for 16-QAM signal is proposed. It combines Modified Modulus algorithm (MCMA) and Modified decisiondirected (MDD) algorithm. By exploiting the inherent structural relationship between the 4-QAM signal's coordinates and 16-QAM signals' coordinates, another style of cost function for Constant Modulus algorithm (CMA) is defined, and we have proved that MCMA with such cost function outperforms the conventional CMA considerably. Unfortunately, MCMA has the same inherent defect as CMA which is that it is not sensitivity for phase offset of received signals. So when it occurs, the performance of MCMA will be impaired and even MCMA cannot work. Accordingly for overcoming the shortcomings of MCMA we introduce the decisiondirected (DD) algorithm, and modify it with the same method as MCMA. Consequently the new concurrent blind equalization with MCMA and MUD is proposed. Simulation results with underwater acoustic channel model show that the proposed algorithm achieves satisfactory performance.
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decisiondirected (DD) operating concurrently (CMA+DD) which is known to ou...
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In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decisiondirected (DD) operating concurrently (CMA+DD) which is known to outperform the CMA considerably, however it still only achieves moderate steady-state mean square error (MSE). Then a new CMA based on modified function is discussed in such combination blind equalization scheme. For the 4-PAM and 16-QAM signals, by adjusting the coordinates of received signals the cost function will become exactly zero when the channel is perfectly equalized. So the proposed algorithm can obtain lower steady-state MSE than CMA+DD. Simulation results show that the proposed method achieves satisfactory performance. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Conference ESIAT2011 Organization Committee.
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decisiondirected (DD) operating concurrently (CMA+DD) which is known to ou...
详细信息
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decisiondirected (DD) operating concurrently (CMA+DD) which is known to outperform the CMA considerably, however it still only achieves moderate steady-state mean square error (MSE). Then a new CMA based on modified function is discussed in such combination blind equalization scheme. For the 4- PAM and 16-QAM signals, by adjusting the coordinates of received signals the cost function will become exactly zero when the channel is perfectly equalized. So the proposed algorithm can obtain lower steady-state MSE than CMA+DD. Simulation results show that the proposed method achieves satisfactory performance.
A novel blind equalizer suitable for high-order QAM signals is proposed,which combines Signed-Error Constant Modulus algorithm(SE-CMA) and decisiondirected(DD) *** proposed algorithm makes full use of the advantages ...
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A novel blind equalizer suitable for high-order QAM signals is proposed,which combines Signed-Error Constant Modulus algorithm(SE-CMA) and decisiondirected(DD) *** proposed algorithm makes full use of the advantages of SE-CMA and DD algorithm and these two algorithms operate *** with underwater acoustic channels are used to compare the proposed algorithm with the famous Constant Modulus algorithm(CMA).The simulation results show that the proposed algorithm has faster convergence rate and lower steadystate mean square error.
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm(CMA) and a decisiondirected(DD) operating concurrently(CMA+DD) which is known to outpe...
详细信息
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm(CMA) and a decisiondirected(DD) operating concurrently(CMA+DD) which is known to outperform the CMA considerably, however it still only achieves moderate steady-state mean square error(MSE). Then a new CMA based on modified function is discussed in such combination blind equalization scheme. For the 4-PAM and 16-QAM signals, by adjusting the coordinates of received signals the cost function will become exactly zero when the channel is perfectly equalized. So the proposed algorithm can obtain lower steady-state MSE than CMA+DD. Simulation results show that the proposed method achieves satisfactory performance.
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