• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.79-84
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• 2018

This paper relates with the performance improvement of SE-MMA (Signed Error-Multiple Modulus Algorithm) adaptive equalization algorithm that is used for the reduction of the intersymbol interference due to the distortion which occurs in the communication channel for the transmission of 16-QAM nonconstant modulus signal.. In the conventional MMA, the fixed modulus value that is second order statistics of transmitting signal were used, and the SE-MMA was introduced in order to the simplification of the algorithm's arithmetic operation. The SE-MMA have a fast convergence speed than MMA, but it has a problem of degradation of equalization performance in the steady state due to the arithmetic simplification. In this paper, we propose the new algorithm AV-SE-MMA (Adaptively Varying-SE-MMA) that uses the adaptive varying modulus in order to obtain the error signal for updating the adaptive equalizer coefficient, and its equalization performance were confirmed by simulation. In this paper, the performance of SE-MMA and proposed algorithm were compared, and the equalizer output signal constellation, residual isi, MSE and SER in order to confirm the robustness of noise were used as performace index. As a result of performance comparison, the AV-SE-MMA has better performance in output signal constellation, residual isi and MD compared to the SE-MMA, but it was confirmed that the AV-SE-MMA has similar in the SER performance that means the robustness to the noise.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.109-114
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• 2015

This paper relates with the eualization performance of Adaptive Varying-MMA (AV-MMA) in order to the minimization of intersymbol interference that is occurs in the nonlinear communication channel. In order to obtain the error signal in the tap coefficient updating process of adaptive equalization algorithm, the present MMA uses the constant modulus. But in AV-MMA, the adaptively varying modulus are used according to the equalizer output, it is possible to reduce the error signal and possbile to improving the overall equalization performance. In order to improved equalization performance of the AV-MMA in the 64-QAM signal, the present MMA performance were compared. For this, the output signal constellation of equalizer, residual isi, maximum distortion, MSE and SER curves are applied. As a result of computer simulation, the AV-MMA has more better performance in the every performance index than MMA, and the SER performance shows that it has more robustness in high SNR environmnet compared to MMA.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.37-42
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• 2007

In this paper, we analyzed the performance of OFDM systems with adaptive equalizer that considers the frequency offset, the frequency non-selective fading, and two-path microwave Rummer's model channels. First of all, it is analyzed that the performance degradation, which is caused by the offset and the non-selective fading channel, through simulation. As the results of the simulation, the performance of the OFDM system is greatly influenced by the offset and channels. The more the frequency offset is, the worse the performance of the OFDM system is. However, if the adaptive equalizer is adopted to the OFDM system, the performance is enhanced up to the limited rang.

• ETRI Journal
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• v.29 no.1
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• pp.50-58
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• 2007

Robust adaptive beamforming based on worst-case performance optimization is investigated in this paper. It improves robustness against steering vector mismatches by the approach of diagonal loading. A closed-form solution to optimal loading is derived after some approximations. Besides reducing the computational complexity, it shows how different factors affect the optimal loading. Based on this solution, a performance analysis of the beamformer is carried out. As a consequence, approximated closed-form expressions of the source-of-interest power estimation and the output signalto-interference-plus-noise ratio are presented in order to predict its performance. Numerical examples show that the proposed closed-form expressions are very close to their actual values.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.337-340
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• 1997

In this paper we propose direct and indirect adaptive controllers for a nonlinear multivariable steam generating unit(200MW). In the direct adaptive scheme the estimation of the controller parameter are achieved from tracking error, while in the indirect approach the unknown parameter of the boiler system is estimated by the Hopfield network-based identifier. The performance of two proposed adaptive controllers is shown through simulations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.9
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• pp.1456-1467
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• 1990

The time domain adaptive noise canceller (time domain ANC) with the adaptive compensator and its algorithm, so called compensated least mean squares(CLMS) algorithm, had been introduced to improve the performance of ANC[1]. In this paper the time domain ANC with the adaptive compensator is transformed into the frequency domain ANC with the adaptive ocmpensator. An compensated frequency-domain least mean squares(CFLMS) algorithm that can adapt the proposed frequency domain ANC is presented.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.179-182
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• 2002

In this paper, we propose a wavelet based adaptive algorithm which improves the convergence speed and reduces computational complexity using the fast running FIR filtering efficiently We compared the performance of the proposed algorithm with time and frequence domain adaptive algorithm using computer simulation of adaptive noise canceler based on synthesis speech. As the result, the proposed algorithm is suitable for adaptive signal processing area using speech or acoustic field.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.427-430
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• 2003

This paper proposes a modified generalized side-lobe canceller with a summed adaptive filter and an adaptive compensator. A summed adaptive filter reduces computational loads and the adaptive compensator minimizes the misadjustment of the adaptive filter coefficients . Computer simulations explain the performance improvement of the proposed method and the conventional generalized side-lobe canceller.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.423-429
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• 2007

Since the wireless smart card has played a main role in the identification security application for the building access; this research has its purpose to improve the performance of the smart card system and aims to offer more convenient to user. The contactless cards do not require insertion into a card reader and can work up to centimeters away from the reading device. To be able to cope with this performance the controlling of power consumption through the adaptive modulation and error control is needed. This paper addresses a forward error control (FEC) scheme with the adaptive Reed-Solomon code rate and an M-ary frequency shift keying (M-FSK) modulation scheme with the varying symbol size M over the link. The result of comparing energy efficiencies of adaptive error correction and adaptive modulation to other various static schemes shows to save over 50% of the energy consumption.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.27-39
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• 2016

This paper considers variable selection in the sparse vector autoregressive (sVAR) model where sparsity comes from setting small coefficients to exact zeros. In the estimation perspective, Davis et al. (2015) showed that the lasso type of regularization method is successful because it provides a simultaneous variable selection and parameter estimation even for time series data. However, their simulations study reports that the regular lasso overestimates the number of non-zero coefficients, hence its finite sample performance needs improvements. In this article, we show that the adaptive lasso significantly improves the performance where the adaptive lasso finds the sparsity patterns superior to the regular lasso. Some tuning parameter selections in the adaptive lasso are also discussed from the simulations study.