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 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.
Most of the cost functions used for blind equalization are non -con vex and non -linear functions of tap weights, when implemented using linear finite impulse response (FIR) filter structures. Thus, a blind equalizati...
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Most of the cost functions used for blind equalization are non -con vex and non -linear functions of tap weights, when implemented using linear finite impulse response (FIR) filter structures. Thus, a blind equalization scheme with a non -linear structure that can form non -convex decision regions is desirable. In this paper, a scheme for blind equalization of non-stationary channels using complex valued feed-forward neural network is presented. The complex valued activation function, suitable for non-stationary environment is introduced and the learning algorithm based on the constant modulus algorithm (CMA) cost function is derived. The improved performance of the proposed scheme is confirmed through computer simulations.
According to the disadvantages of large mean square error(MSE)and slow convergence rate of constant modulus algorithm (CMA),a fractionally spaced combining with spatial diversity blind equalization algorithm based on ...
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According to the disadvantages of large mean square error(MSE)and slow convergence rate of constant modulus algorithm (CMA),a fractionally spaced combining with spatial diversity blind equalization algorithm based on wavelet transformation (WT-FS-SDE-CMA) was *** this proposed algorithm,spatial diversity technique was applied to blind equalizer to reduce effect of multi-path fading channel on input signals,fractionally spaced equalizer (FSE) was employed for avoiding the spectrum aliasing caused by the under-sampling and decreasing the MSE of equalizer,and orthogonal wavelet transform was introduced into fractionally spaced equalizer (FSE) to decrease the autocorrelation of the input *** proposed algorithm has smaller mean square error and faster convergence rate comparison with the spatial diversity equalizer based on CMA (SDE-CMA) and fractionally spaced spatial diversity equalizer based on CMA(FS-SDE-CMA).The performance of the proposed algorithm is best proved by the computer simulation in underwater acoustic channels.
A novel blind equalizer suitable for high-order QAM signals is proposed,which combines Signed-Error constant modulus algorithm(SE-CMA) and Decision Directed(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 Decision Directed(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.
The inter-symbol interference caused by channel distortion in the communication process seriously affects the communication quality, and this problem is often solved by equalization technology. The principle of the tr...
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ISBN:
(纸本)9781450396899
The inter-symbol interference caused by channel distortion in the communication process seriously affects the communication quality, and this problem is often solved by equalization technology. The principle of the traditional blind equalization constant modulus algorithm (CMA) with fixed step is introduced, and the problem of fast convergence speed and small steady-state error is analyzed by simulation. In order to solve this problem, a blind equalization algorithm with variable step size based on CMA is proposed. In order to solve the problem of fast convergence speed and small steady-state error, the CMA algorithm is improved and the principle of the improved algorithm is described, and the influence of the step on the performance of the algorithm is analyzed. Finally, the simulation experiment proves that the improved algorithm can speed up the convergence speed and keep a small steady-state error at the same time.
The constant modulus algorithm(CMA) equalizer is perhaps the best known and the most popular scheme for blind adaptive channel equalization. In this paper, a modified constant modulus algorithm(modified CMA or MCMA) i...
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The constant modulus algorithm(CMA) equalizer is perhaps the best known and the most popular scheme for blind adaptive channel equalization. In this paper, a modified constant modulus algorithm(modified CMA or MCMA) is proposed by modifying its error function. We have discussed the MCMA to blind channel equalization for baud-rat sampling in single-user case. Computer simulations are provided for 8PSK signals in noise environments under frequency selective channels. Results demonstrate that the MCMA displays much superior performance to the CMA for both convergence-time and intersymbol interference(ISI) or mean square error(MSE).
Aiming at the slow convergence rate and the high mean square error of constant modulus algorithm(CMA) ,a new orthogonal Wavelet Transform based Sign Decision Dual-mode blind equalization algorithm(WT-SDDA) is *** the ...
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Aiming at the slow convergence rate and the high mean square error of constant modulus algorithm(CMA) ,a new orthogonal Wavelet Transform based Sign Decision Dual-mode blind equalization algorithm(WT-SDDA) is *** the proposed algorithm,orthogonal Wavelet Transform based constant modulus algorithm (WT-CMA) is integrated with orthogonal Wavelet Transform based Stop-and-Go Changeable modulus blind equalization algorithm (WT-SG-CMA),and the switch process is decided by the sign *** tests with underwater acoustic channel shows that the proposed WT-SDDA algorithm outperforms the CMA and the WT-CMA in the convergence rates and residual mean square error and that it has the faster convergence rate than the WT-SG-CMA under condition of the same residual error.
In order to improve the ability of normal mode blind equalizer to deal with inter-code crosstalk,a blind equalization algorithm based on brainstorming algorithm is *** algorithm starts with the problem of unsatisfacto...
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In order to improve the ability of normal mode blind equalizer to deal with inter-code crosstalk,a blind equalization algorithm based on brainstorming algorithm is *** algorithm starts with the problem of unsatisfactory initialization of the equalizer,and uses the brainstorming algorithm to quickly and accurately find the advantages of the global solution,reducing the initial mean square error of the system;on this basis,from the perspective of the convergence speed and convergence stability of the weighing instrument,the adaptive ability of the variable step error function is used to improve the equalization effect of the *** results show that the new equalization algorithm can reduce the initial mean square error,accelerate the convergence speed of the equalizer,and improve the communication performance of the system.
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...
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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.
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.
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