In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus sig...
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In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus signals such as higher-order PAM signals, the CMA just achieve moderate steady-state mean square en-or (MSE) which may not be sufficient for the system to obtain adequate performance. By studying the amplitude relationship between different constellations of PAM signals, a new amplitude transfomiation method is proposed. According to such method the non-constantmodulus signals can be changed to be constantmodulus, and then using it to the CMA the zero steady-state MSE can be obtained. The efficiency of the proposed method is proved by computer simulations. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Conference ESIAT2011 Organization Committee.
The constant modulus algorithm has a relatively slow convergence speed in digital coherent receivers when compared to other algorithms, such as the least mean square. This paper proposes and experimentally demonstrate...
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The paper proposes a novel spread quadrature amplitude modulation (S-QAM) technique with high SNR improvement for high-order QAM channels. Simulated and experimental bit error rate (BER) performance analyses of the pr...
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The paper proposes a novel spread quadrature amplitude modulation (S-QAM) technique with high SNR improvement for high-order QAM channels. Simulated and experimental bit error rate (BER) performance analyses of the proposed technique in blind and non-blind equalizers are obtained by using single carrier (SC) WiMAX (IEEE 802.16-2004) radio. Instead of using any one particular type of channel profile, this study concentrates on true frequency selective Rayleigh fading channels in the real-time WiMAX radio environment around 3.5 GHz. The constant modulus algorithm (CMA) blind equalizer has been compared with the popular non-blind equalizers, Recursive Least Squares (RLS) and Least Mean Squares (LMS) algorithm, as benchmarks. It has been proven in experimental and simulated channels that CMA blind equalizer, using the proposed technique, can be considered as a low complexity, spectrum efficient and high performance time domain equalizations to be embedded in a transceiver for the next generation communications. Furthermore the proposed technique has also reduced approximately till 5 dB and 7.5 dB performance differences between non-blind and blind equalizers for 16-QAM and 64-QAM, respectively. The simulation results have demonstrated that the simulated and experimental studies of the proposed technique are compatible with each other and extremely satisfying.
The constant modulus algorithm (CMA) is recognized as the most widely used algorithm in blind channel equalization practice. However, the CMA cost function exhibits local minima, which often leads to ill-convergence. ...
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The constant modulus algorithm (CMA) is recognized as the most widely used algorithm in blind channel equalization practice. However, the CMA cost function exhibits local minima, which often leads to ill-convergence. This paper proposes a concurrent equalizer, in which a Soft Decision Directed (SDD) equalizer operates cooperatively with a CMA equalizer, controlled through a non-linear link that depends on the system a priory state. The simulation results show that the proposed equalizer has faster convergence rate and lower steady-state mean square error than the CMA equalizer.
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decision directed (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 decision directed (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.
In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus sig...
详细信息
In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus signals such as higher-order PAM signals, the CMA just achieve moderate steady-state mean square error (MSE) which may not be sufficient for the system to obtain adequate performance. By studying the amplitude relationship between different constellations of PAM signals, a new amplitude transformation method is proposed. According to such method the non-constantmodulus signals can be changed to be constantmodulus, and then using it to the CMA the zero steady- state MSE can be obtained. The efficiency of the proposed method is proved by computer simulations.
In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus sig...
详细信息
In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constantmodulus signals such as higher-order QAM signals, the CMA just achieve moderate steady-state mean square error (MSE) which may not be sufficient for the system to obtain adequate performance. By studying the amplitude relationship between different constellations of QAM signals, a new amplitude transformation method is proposed. According to such method the non-constantmodulus signals can be changed to be constantmodulus, and then using it to the CMA the zero steady- state MSE can be obtained. The efficiency of the proposed method is proved by computer simulations.
In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm(CMA) and a decision directed(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 decision directed(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.
Blind Spatial Diversity Equalizer(SDE) is a famous adaptive equalization technique to overcome signal fading and inter-symbol interference(ISI) simultaneously without the aid of training sequences. The key blind algor...
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Blind Spatial Diversity Equalizer(SDE) is a famous adaptive equalization technique to overcome signal fading and inter-symbol interference(ISI) simultaneously without the aid of training sequences. The key blind algorithm in SDE is constant modulus algorithm(CMA). And the weaknesses of these algorithms such as slow convergence rate and large residual error can also occur in SDE and degrade the performance of SDE. By studying the geometrical relationship of the 16-QAM signal coordinates, a novel SDE suitable for 16-QAM signal is proposed. Compared with SDE based on CMA or MCMA, the proposed SDE has faster convergence rate and lower residual error in computer simulation.
The constant modulus algorithm(CMA) is recognized as the most widely used algorithm in blind channel equalization practice. However, the CMA cost function exhibits local minima, which often leads to ill-convergence. T...
详细信息
The constant modulus algorithm(CMA) is recognized as the most widely used algorithm in blind channel equalization practice. However, the CMA cost function exhibits local minima, which often leads to ill-convergence. This paper proposes a concurrent equalizer, in which a Soft Decision Directed(SDD) equalizer operates cooperatively with a CMA equalizer, controlled through a non-linear link that depends on the system a priory state. The simulation results show that the proposed equalizer has faster convergence rate and lower steady-state mean square error than the CMA equalizer.
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